AAQBT

The American Academy of Quantum

Biofeedback Technology

Located in Rio Rancho, New Mexico since 1988

Electro-Physiological-Reactivity (EPR)

By William Nelson

ABSTRACT: Situated on a golf course in New Mexico the Land of Enchantment, in the City of Vision Rio

Rancho the AAQBT made history. We tested 935 subjects in Denver and New Mexico to understand the

basic body electric measures to better understand the nature of the energetic medicine. This review

report scrutinizes a comparison between skin conductance, inductance, and capacitance (collectively

known as the Trivector), and SCIO Electro-Physiological-Feedback-Xrroid EPR reactivity. We measured

the 935 subject’s reactivity patterns to nosodes, allersodes, isodes, Sarcodes, and classic homeopathy

using the EPFX biofeedback system. Significant profiles revealed an accuracy of about 71% to known

medical conditions. The reactance was a collective measure of change in resistance, change in

capacitance, and change in inductance (the 3 vectors of the trivector) together referred to as the

reactivity or in this case the EPR.

AAQBT

The American Academy of Quantum

Biofeedback Technology

Located in Rio Rancho, New Mexico since 1988

TRIVECTOR

By William Nelson

ABSTRACT: We tested 935 subjects in Denver and New Mexico to understand the basic body electric

measures to better understand the nature of the energetic medicine. This review report scrutinizes a

comparison between skin conductance, inductance, and capacitance (collectively known as the

Trivector), and SCIO Electro-Physiological-Feedback-Xrroid EPR reactivity. Electricity acts in three basic

dimensions of conductance, inductance and capacitance. These events can be measured and a three

dimensional trivector analysis can be derived. Events display that the Xrroid has a very high

interdependence to culture results, and thus the Xrroid is very helpful in determining the electrical

reactivity of the patient, and in determining the type of infection the patient might have. The overall

correlation was approximately 91%. The existence of many so called false positives or infections that are

subclinical makes reading difficult. The trivector field of a living organism is not static, it is reactive. A

living being is interacting with the environment to be drawn towards nutrition, and repelled from

toxins. Thus with the xrroid we measure which items the patient reacts to and how he reacts so we can

see a profile that might help us learn more about our patient.

AAQBT

The American Academy of Quantum

Biofeedback Technology

Located in Rio Rancho, New Mexico since 1988

SKIN INDUCTANCE

By William Nelson

ABSTRACT: Skin Capacitance is affected by polarization capacitance (where stored charges around an

electrode appear in a near electrolytic medium). We tested 935 subjects in Denver and New Mexico to

understand the basic skin capacity to store charges and other bio-electric measures to better

understand the nature of the body electric. Skin capacitance was measured to range from .01 to .07

microFarads per centimeter squared. If the corneum thickness of 10 micrometers and a dielectric

constant of 2.5 for biological membranes then the capacitance will be about 2 x microFarads per

centimeter squared. Two equivalent electric current paths are measured: one crossing lipid-corneocyte

medium and the other going thru skin appendages. The current-time response of the skin during the

application of rectangular pulses of different voltage amplitudes demonstrates an insightful similarity

with the same characteristics in model and plasma membrane electroporation. A significant (up to three

orders of magnitude) drop of skin resistance happens due to electro-stimulation can be explained by

electroporation of various substructures of stratum corneum. At relatively low voltages (U<30V) this

drop of skin resistance can be ascribed to electroporation of the appendageal ducts. At higher voltages

(U>30V), electroporation of the lipid-corneocyte matrix makes an extra drop of skin resistance.

AAQBT

The American Academy of Quantum

Biofeedback Technology

Located in Rio Rancho, New Mexico since 1988

SKIN CAPACITANCE

By William Nelson

ABSTRACT: Skin Capacitance is affected by polarization capacitance (where stored charges around an

electrode appear in a near electrolytic medium). We tested 935 subjects in Denver and New Mexico to

understand the basic skin capacity to store charges and other bio-electric measures to better

understand the nature of the body electric. Skin capacitance was measured to range from .01 to .07

microFarads per centimeter squared. If the corneum thickness of 10 micrometers and a dielectric

constant of 2.5 for biological membranes then the capacitance will be about 2 x microFarads per

centimeter squared. Two equivalent electric current paths are measured: one crossing lipid-corneocyte

medium and the other going thru skin appendages. The current-time response of the skin during the

application of rectangular pulses of different voltage amplitudes demonstrates an insightful similarity

with the same characteristics in model and plasma membrane electroporation. A significant (up to three

orders of magnitude) drop of skin resistance happens due to electro-stimulation can be explained by

electroporation of various substructures of stratum corneum. At relatively low voltages (U<30V) this

drop of skin resistance can be ascribed to electroporation of the appendageal ducts. At higher voltages

(U>30V), electroporation of the lipid-corneocyte matrix makes an extra drop of skin resistance.

AAQBT

The American Academy of Quantum

Biofeedback Technology

Located in Rio Rancho, New Mexico since 1988

Electro-Acupuncture

By William Nelson

ABSTRACT: Situated on a golf course in New Mexico the Land of Enchantment, in the City of Vision Rio

Rancho the AAQBT made history. We tested 935 subjects in Denver and New Mexico to understand the

basic body electric measures to better understand the nature of the energetic medicine. This review

report scrutinizes a comparison between skin conductance, inductance, and capacitance (collectively

known as the Trivector), and acupuncture points. We surveyed the acupuncture points on the subjects

with a wave form analyzer and a frequency counter. We found that each healthy acu-point had a

particular signature profile. There was a discrete and different frequency band, wave form and signal

intensity showing that each acu-point has its own particular electrical signature. When we supplied this

signature to unhealthy points, the points can improve. This opens to door for an electro-acupuncture

program to measure and treat acu-points and help the body.

Electro-Acupressure - Scientific Explanation

Bio-Physical Mechanisms for the Action of Acupuncture to Explain the Mode of Action of the EPFX (Electro Physiological Feedback Xrroid)

Dr Julian Jessel Kenyon MD Southampton, UK. February, 1995 for the AAQBT

An information and control system using direct current (DC) analogue electrical signals, which runs in connection with the nervous system has been postulated to explain how acupuncture might work, by Robert Becker. Becker is a retired Professor of Orthopaedic Surgery working in New York State. His hypothesis is based on work with limb regeneration in amphibians and on the phenomena of the current of injury.

Becker's hypothesis leads to a whole range of theoretical assumptions as to the phenomena of acupuncture points which have led to the useful practical outcome of the EPFX, using its particular wave form and particular method of point detection. Becker proposed that the signals in the DC system are carried via the neuroglia which are cells surrounding nerve fibres. Currents known to be produced by injury are said to be produced by this glial system, which is associated with growth and repair.

For example, if an injury is created and there is no current of injury, then no

growth or repair occurs. Also electrical currents and associated fields have been shown to be fundamental to differentiation and development in both plants and animals. Becker described a number of spectacular examples or repairabilities, including the regeneration of amputated limbs in newts, and finger-tips in children.

The integration of the glial system with acupuncture was proposed by Becker with acupuncture points considered to be analogous to booster stations along the meridians, which are lines connecting acupuncture points, and these meridian lines are likened to transmission lines for these DC signals. Acupuncture points in meridians do show specific electrical properties, and changes in these characteristics can be used for diagnosis.

Acupuncture points appear to have little or no electrical activity when the tissue or organ which they represent is healthy. When an injury takes place, or disease occurs, a current is produced local to that damage. At the same time the properties of the related acupuncture point change, and there are also some possible changes in polarity of the acupuncture points in relationship to the surrounding skin. Corresponding acupuncture points are usually distant to the site of the injury. This is not always the case but is often so.

A number of conventional electrical circuits can be fitted to this model, and the diode gate is the best explanation. A diode gate is one of the basic building blocks in micro-processors. It seems that in painful conditions a semi-conductor effect blocks the free flow electric charge, thereby leading to a build up of charge, and therefore pain.

The concept of semi conduction is very important to this explanation of mechanism of the acupuncture point. One of the pioneers of modern concepts relating solid state physics, ie, physics not involving moving parts or gasses, sometimes called semi-conduction and biology, was Albert Szent Gorgyi. He won a Nobel prize for work on Vitamin C and biological oxidation. He first introduced the concept of semi-conduction into the biological arena during the 1940s'. Before semi-conduction was suggested, only two methods of conduction of electrical current were known:

Metallic conduction which can be viewed as clouds of electrons moving along a wire.

Ionic conduction which is the conduction of electricity using charged particles (ions). Nerve impulses are conducted in such a manner. Ionic currents work well over short distances, such as the membrane serving nerve fibres, but soon become dissipated over greater distances.

Semi-Conduction is a third means of generating and conducting a current and requires materials to have a very orderly structure so that electrons can move from one atom nucleus to another. Crystals have the necessary

orderly structure. Much body tissue is in the liquid crystal state.

Semi-conductors have characteristics of both insulators and conductors, depending on temperature; they are inefficient in that they can carry only small currents but the current can be readily carried over long distances. Semi-conduction has been an essential cornerstone in the development of all aspects of electronics over the last 40 years.

The idea of a diode, which is a semi-conductor which allows the passage of current in one direction only, is central to the basic explanation of how acupuncture works. This is shown by the three following diagrams:

The current source is the body's own metabolism.

The load is the part of the body which is connected to a specific acupuncture point which is shown on the right of each diagram.

f the load or the specific tissue under question is healthy then the acupuncture point registers no abnormality. If the load is injured in some way, such as in the second diagram, then a current of injury is produced and this blocks the flow of current into the affected area. As a result the current flow from the body's metabolism (current source) backs up and the acupuncture point becomes electrically active.

The third diagram shows the acupuncture point being treated with a biphasic signal.

This is of great importance as a signal with either positive or negative polarity, and not with negative and positive polarity, which is what we mean by a biphasic signal, is the most likely input to unblock the diode and send a current into the affected area which then helps that area to heal.

One other characteristic of the biphase impulse given by the EPFX is the very sharp rise and fall tides. This gives a very resonant wave form with a very rich fourier transform. This is basically a frequency content of the wave form. A particular wave form used is very rich in harmonics, and therefore is a very resonant wave form. Resonance is a very important phenomena in biology, therefore the EPFX makes use of this, so the point is able to resonate with one or a number of the many frequencies contained within the EPFX wave form. This explanation suggests that acupuncture points become particularly active after injury or disease, which is exactly what is found in practice.

Acupuncture points are usually negative with respect to the surrounding skin, with a value of -0.05 millivolts as being fairly average. Higher negative values represent increased electrical activity in the corresponding anatomical area with readings of -0.25 millivolts. This is found in functional pathology where there is no actual organic change or damage. In acute conditions, this level can go up to as high as -0.75 millivolts. In extreme cases readings over-100 millivolts is usually associated with severe pain. In other situations a high positive value is found, particularly with infections, psoriasis, asthma and allergies, and readings of +0.5 millivolts are not unusual. A low permanent positive value such as 0.001 millivolts is present in some chronic conditions such as in chronic Osteo-arthritis.

What this means is that it is possible to detect acupuncture points looking at voltage change. However, the most common method used to find acupuncture points is looking for areas of high conductance or low resistance (these both mean the same thing). This is what is used in the EPFX, and the sensitive skin resistance meter is built in to the EPFX with the operator connected to the EPFX (part of the hand grip on the EPFX is electro-conductive and therefore forms one side of the circuit). Many studies have shown acupuncture points to be areas of low resistance.

The fact that semi-conductor properties are present in acupuncture points can be shown by taking the reading over an acupuncture point with a simple voltmeter. If the electrodes are reversed, and if ionic conduction was solely responsible, then the reading would remain the same but would have a different polarity, ie, from negative to positive. In practice this rarely happens and the second measurement with the electrodes the other way round is often different in varying degrees to the first orientation of the electrodes. This indicates a partial, or in some cases total, semi-conductor effect.

What we do know from traditional Chinese acupuncture theory is that meridians do have a direction of flow going from the first numbered point on the meridian to the last numbered point on the meridian such as in the bladder meridian ( the largest meridian in the body). This starts at bladder one and ends at bladder 67. The flow is from one through all the intervening points to bladder 67. Therefore reverse measurements as described here provide evidence for a greater flow of current in one direction than the other, therefore substantiating the ancient Chinese view of the point numbering.

What is found is that if a bi-polar electrical current is driven through a semi conductive tissue then normal conductive properties will be restored, the stored charge in the damaged area will be discharged and the resultant symptoms will disappear, often with sufficient treatment this can result in a complete disappearance of the problem. This phenomena is illustrated in the diagrams. To summarise, therefore:

Acupuncture points only become electrically active when a dysfunction is present in the body.

The size and shapes of acupuncture points appear to vary considerably. Electrical measurements reveal them in some cases to be zones within which a number of highly localised points may exist, and in other situations they appear to be highly localised points even localised within a small number of millimetres.

Different acupuncture points in the zone appear to become active in different situations. The points are dynamic, becoming particularly active after injury or disease.

We do know that stimulation of a specific acupuncture point results in functional alterations in the organ or part of the organ, or soft tissue, or whatever structure is connected with the acupuncture point. This functional alteration is always in the direction of normality and can, in some cases, lead to the resolution of actual organic pathology.

In conclusion, this simple biophysical model of acupuncture can be confirmed by any reasonably committed investigator, using a simple multi-meter. This confirms the semi-conductor properties of acupuncture points and their related tissue. It also provides a scientific basis for the use of a biphasic current of stimulation, and the use of a highly resonant wave form so that each point has a selection of frequencies (harmonics) from which to choose.

This model also explains why, through repeated treatment, functional, and in many cases organic, pathology can respond and resolve. Essentially what an acupuncture point is expressing when it becomes active (in other words where disease, functional or organic, is present), is it is trying to resolve biophysically the electrical abnormality produced by the injury or disease in the affected tissue.

The use of a biphasic current over the affected point facilities this process, which in turn leads to resolution of the original pathology.

This theory, therefore, has the beauty of having considerable scientific evidence, and of it being able to be confirmed by simple experiments which can be carried out by anybody of reasonable intelligence using a multimeter.

This, therefore, in turn leads to a sensible design for pieces of equipment such as the EPFX

J Altern Complement Med.

Characteristics of electrical skin resistance at acupuncture points in healthy humans. Kramer S, Winterhalter K, Schober G, Becker U, Wiegele B, Kutz DF, Kolb FP, Zaps D, Lang PM, Irnich D.

Source

Multidisciplinary Pain Centre, Department of Anaesthesiology, University of Munich, Munich, Germany.

Abstract

OBJECTIVES:

The aim of this study was to evaluate the phenomenon of electrical skin resistance (ESR) changes at

different acupuncture points (APs).

SETTING:

This single-blinded study was performed at the hospital of the University of Munich.

DESIGN:

Six common APs were measured (TE5, PC6, LU6, ST36, SP6, GB39) in 53 subjects. Subgroups were

formed with varying time intervals for follow-ups (1 minute, 1 hour, 1 week) and a varying grade of

reduction of the stratum corneum.

METHODS:

Electrical skin resistance measurements (ESRMs) were taken from a skin area of 6 x 6 cm using an array

consisting of 64 (8 x 8) electrodes. The electrodes corresponding to the AP were located and the ESRM

results were compared to those of the surrounding electrodes. The methodological setting made it

possible to minimize major influence factors on electrical skin impedance measurements.

RESULTS:

A total of 631 ESRMs was evaluated: In 62.8% of the measured APs, no significant ESR difference was

found. In 234 (37.2%) of the ESRMs, the ESR at the AP was significantly different from the surrounding

skin area, with 163 (25.9%) points showing a lower and 71 (11.3%) points showing a higher ESR.

Reproducibility was extremely high after 1 minute but was low after 1 hour and 1 week.

CONCLUSIONS:

This study shows that electrical skin resistance at APs can either be lower or higher compared to the

surrounding area. The phenomenon is characterized by high short-term and low long-term reproducibility.

Therefore, we conclude that APs might possess specific transient electrical properties. However, as the

majority of the measured APs did not show a changed ESR, it cannot be concluded from our data that

electrical skin resistance measurements can be used for acupuncture point localization or

diagnostic/therapeutic purposes.

Comment in

J Altern Complement Med. 2009 Oct;15(10):1059.

PMID:

19422323

[PubMed - indexed for MEDLINE]

Characteristics of Electrical Skin Resistance at Acupuncture Points in Healthy Humans

AUTHOR(S)

Kramer, Sybille; Winterhalter, Kathrin; Schober, Gabriel; Becker, Ursula; Wiegele, Bernhard; Kutz, Dieter F.; Kolb,

Florian P.; Zaps, Daniela; Lang, Philip M.; Irnich, Dominik

PUB. DATE

May 2009

SOURCE

Journal of Alternative & Complementary Medicine;May2009, Vol. 15 Issue 5, p495

SOURCE TYPE

Academic Journal

DOC. TYPE

Article

ABSTRACT

Objectives: The aim of this study was to evaluate the phenomenon of electrical skin resistance (ESR) changes at

different acupuncture points (APs). Setting: This single-blinded study was performed at the hospital of the University

of Munich. Design: Six common APs were measured (TE5, PC6, LU6, ST36, SP6, GB39) in 53 subjects. Subgroups

were formed with varying time intervals for follow-ups (1 minute, 1 hour, 1 week) and a varying grade of reduction of

the stratum corneum. Methods: Electrical skin resistance measurements (ESRMs) were taken from a skin area of 6

� 6 cm using an array consisting of 64 (8 � 8) electrodes. The electrodes corresponding to the AP were located and

the ESRM results were compared to those of the surrounding electrodes. The methodological setting made it

possible to minimize major influence factors on electrical skin impedance measurements. Results: A total of 631

ESRMs was evaluated: In 62.8% of the measured APs, no significant ESR difference was found. In 234 (37.2%) of

the ESRMs, the ESR at the AP was significantly different from the surrounding skin area, with 163 (25.9%) points

showing a lower and 71 (11.3%) points showing a higher ESR. Reproducibility was extremely high after 1 minute but

was low after 1 hour and 1 week. Conclusions: This study shows that electrical skin resistance at APs can either be

lower or higher compared to the surrounding area. The phenomenon is characterized by high short-term and low

long-term reproducibility. Therefore, we conclude that APs might possess specific transient electrical properties.

However, as the majority of the measured APs did not show a changed ESR, it cannot be concluded from our data

that electrical skin resistance measurements can be used for acupuncture point localization or diagnostic/therapeutic

purposes.

Measurement of electrical resistance at the skin surface

over Jing-well acupuncture points in chronic pain states

Show full item record

Title: Measurement of electrical resistance at the skin surface over Jing-well acupuncture points in chronic pain states

Author: Turner, Linda Catherine

Degree Doctor of Philosophy - PhD

Program Interdisciplinary Studies

Copyright

Date: 2010

Abstract:

The purpose of this project was to investigate an energy-based model of chronic pain. Given skepticism about the domain of energy-

based healing as treatment for chronic pain, it has been suggested that research can only be furthered by the use of laboratory

methods that allow for rigorous and controlled studies of the hypothesized biological pathways. A review of the literature established

several measurement devices that could be used to measure the human energy field (biofield) but only an ohmmeter measuring

electrical resistance at 24 Jing-well points showed promising biometrics. A reliability study conducted within this larger study

demonstrated an impressive mean Cronbach’s alpha of .88 for the ohmmeter used in this study. Participants in the experimental group

with rheumatoid arthritis and a pain level of at least 3 (0-10 scale) were compared to participants in the control group who had no

medical diagnosis and were pain free. The measurements from the ohmmeter were compared to heart rate, heart rate variability,

blood pressure, Pain Catastrophization Scale, McGill Melzack Pain Questionnaire, and Profile of Mood States. There were significant

differences between the experimental group and the control group on conventional markers of pain except heart rate variability.

Similarly, there were significant differences between Jing-well measurements for the acupuncture points labeled ‘Bladder’, ‘Gall

Bladder’ and ‘Small Intestine’ thus differentiating between the experimental and control groups. Ingesting an analgesic did not lead to

significant between group changes in acupuncture point activity after one hour. Electrical resistance at all Jing-well points was highly

correlated suggesting that they tap into a global level of physiological activation. Electrical resistance at acupuncture points was

significantly correlated with total pain (McGill Melzack Pain Questionnaire) and some acupuncture point activity was correlated with

the ‘Tension/Anxiety’ and ‘Friendly’ dimensions of the Profile of Mood States. In summary, it was concluded that the ohmmeter and its

measurements possessed criterion validity for distinguishing pain from no pain states. This research protocol appears to be suitable for

further validation research on the criterion validity of energy-based models of disease and can be seen as a bridge between Western

and Chinese medicine.

URI: http://hdl.handle.net/2429/29638

ELECTRICAL DETECTION OF ACUPUNCTURE POINTS

Nicolae-Marius Barlea(1)

, Horatiu Sibianu(2)

, Radu V. Ciupa (3)

(1)Technical University of Cluj-Napoca, Physics Department, Romania, E-mail: mbirlea@phys.utcluj.ro (2)Technical University of Cluj-Napoca, Physics Engineering student, Romania (3)Technical University of Cluj-Napoca, Electrotechnics Department, Romania

ABSTRACT: Comparative total impedance measurements for normal skin and

acupuncture points are presented. The behavior of the impedance and admittance with

the frequency for active points and indifferent skin is analyzed. It is indicated the

optimum frequency domain for the detection of the acupuncture points.

1. INTRODUCTION

Acupuncture points (AP) are very important for medical diagnosis and therapy. The malfunction

of the internal organ correlated with the AP lowers the electrical resistance of the AP.

The AP has a lower electrical resistance and a greater electrical capacitance than normal skin. In

literature [1] is stipulated an AP resistance of tens kiloohms, with 20-50% lower than the normal

skin and an AP capacitance few hundred times greater than that of the normal skin.

The human body is a large electrolytic system with complex electrochemical reactions. There are

only few direct electrical methods for the human body investigation and for this reason we

consider important understanding the skin impedance behavior.

2. EXPERIMENTAL METHOD

We measured the impedance of the skin for various frequencies and different effective applied

electrical tensions. The electrical set-up consists of a Hewlett Packard Function Generator

(HP3310A), a Hung Chang digital multimeter HC4520A with 4 1/2 digits. The test electrode is

made from graphite (inert material electrode) with 2mm diameter (3,14 mm2 section area) and

the reference electrode is made from silicone rubber with graphite (4 cm2 area and

120 electrical resistance), or alternative lead foil.

Fig. 1. The experimental arrangement for the skin impedance measurement

The measurements were done especially for the point P1 on the lung meridian placed near the

corner of the thumbnail and comparatively for the IG1 and IG4 points. We made measurements

using signals both square wave and sine wave. The sensitivity was greater for square wave signal

than sine wave.

We put the reference electrode either on the indifferent skin or in mouth on the tongue. The best

results (stability of the digital microampermeter indications) were obtained with the reference

electrode on the tongue. The test electrode was applied with a light pressure on the skin. Because

we pressed the electrode with the free hand, the applied pressure was variable modifying the

measured skin impedance. The measured values scattering was tolerable, between 10% and 20%

of medium value. Much more difficult to handle was the position effect at low frequency (under

100 Hz). Here the smallest deviation from the AP position greatly changes the measured value of

the impedance.

3. EXPERIMENTAL RESULTS

The effective tension applied was of 2,05V and the signal shape was square wave. Experimental

results are displayed in table 1, where Zindif is the skin impedance, Zactiv is acupuncture point

impedance and S is the sensitivity of the method, the ratio between Zindif and Zactiv.

Table 1

f (Hz) Zindif(k ) Zactiv(k ) S=ZI /Za

5 800 20 40

50 480 12 40

100 350 8 43,7

150 340 15 22,7

200 300 16,5 18,2

500 135 17 7,9

1000 75 14 5,3

1500 50 11,9 4,2

The impedance diagram of normal skin versus frequency Zindif = F(f) and especially the

admittance (1/Zindif) diagram versus frequency, fig.2, reveals the characteristic behavior for an

electrical capacitance:

1/Zindif = 2 C f

i.e. 1/Z is a linear function of frequency. In reference [2] the skin impedance is about 1k for a

10 ms pulse but only 50 for a 0.1 ms pulse.

Fig. 2. The impedance Z and the admittance 1/Z of the skin versus frequency

There is a slight non-linearity in the range of low frequencies (between 50 and 200 Hz) which

could have an experimental origin, but this phenomenon need further investigations because in

the same frequency domain there are a clear anomalous behavior of the AP impedance, i. e. there

it is a low impedance region of the AP centered on 100 Hz.

The acupuncture points have clearly lower impedance than normal skin. The graph of the

frequency dependence of the AP impedance is more complex as we see in fig.3. The capacitive

behavior of the AP impedance is less pronounced comparatively to that of the normal skin.

Fig. 3. The impedance and the admittance of the acupuncture point P11 versus

frequency

4. DISCUSSION

For reliable detection of the acupuncture points it is necessary to exist a clear difference between

normal skin and active points. At low frequencies (under 20Hz) the AP impedance is few times

lower than the normal skin impedance, but it is very difficult to localize the point because for a

displacement under 1mm the impedance measured value became that for the normal skin. At

high frequencies (over 500Hz) the normal skin impedance is very close to the AP impedance, as

seen in fig.4, but the transition from the normal skin impedance to the AP impedance is

smoother.

Fig. 4. Method sensitivity S=Zindif / Zactiv versus frequency

A good choice for the measuring frequency could be somewhere between 20 and 200 Hz,

probably 100 Hz for a good noise rejection.

5. REFERENCES

[1] Dumitrescu I. Fl., Constantin D., Modern scientific acupuncture (in Romanian), Junimea

Publishing House, Iaşi 1977

[2] Low J., Reed A., Dyson M., Electrotherapy explained, Butterworth-Heinemann, 1990

REACTANCE AND IMPEDANCE --

INDUCTIVE

AC resistor circuits

Pure resistive AC circuit: resistor voltage and current are in phase.

If we were to plot the current and voltage for a very simple AC circuit consisting of a

source and a resistor (Figure above), it would look something like this: (Figure below)

Voltage and current “in phase” for resistive circuit.

Because the resistor simply and directly resists the flow of electrons at all periods of

time, the waveform for the voltage drop across the resistor is exactly in phase with the

waveform for the current through it. We can look at any point in time along the

horizontal axis of the plot and compare those values of current and voltage with each

other (any “snapshot” look at the values of a wave are referred to asinstantaneous

values, meaning the values at that instant in time). When the instantaneous value for

current is zero, the instantaneous voltage across the resistor is also zero. Likewise, at

the moment in time where the current through the resistor is at its positive peak, the

voltage across the resistor is also at its positive peak, and so on. At any given point in

time along the waves, Ohm's Law holds true for the instantaneous values of voltage

and current.

We can also calculate the power dissipated by this resistor, and plot those values on

the same graph: (Figure below)

Instantaneous AC power in a pure resistive circuit is always positive.

Note that the power is never a negative value. When the current is positive (above the

line), the voltage is also positive, resulting in a power (p=ie) of a positive value.

Conversely, when the current is negative (below the line), the voltage is also negative,

which results in a positive value for power (a negative number multiplied by a

negative number equals a positive number). This consistent “polarity” of power tells

us that the resistor is always dissipating power, taking it from the source and releasing

it in the form of heat energy. Whether the current is positive or negative, a resistor still

dissipates energy.

AC inductor circuits

Inductors do not behave the same as resistors. Whereas resistors simply oppose the

flow of electrons through them (by dropping a voltage directly proportional to the

current), inductors oppose changes in current through them, by dropping a voltage

directly proportional to the rate of change of current. In accordance with Lenz's Law,

this induced voltage is always of such a polarity as to try to maintain current at its

present value. That is, if current is increasing in magnitude, the induced voltage will

“push against” the electron flow; if current is decreasing, the polarity will reverse and

“push with” the electron flow to oppose the decrease. This opposition to current

change is called reactance, rather than resistance.

Expressed mathematically, the relationship between the voltage dropped across the

inductor and rate of current change through the inductor is as such:

The expression di/dt is one from calculus, meaning the rate of change of instantaneous

current (i) over time, in amps per second. The inductance (L) is in Henrys, and the

instantaneous voltage (e), of course, is in volts. Sometimes you will find the rate of

instantaneous voltage expressed as “v” instead of “e” (v = L di/dt), but it means the

exact same thing. To show what happens with alternating current, let's analyze a

simple inductor circuit: (Figure below)

Pure inductive circuit: Inductor current lags inductor voltage by 90o.

If we were to plot the current and voltage for this very simple circuit, it would look

something like this: (Figure below)

Pure inductive circuit, waveforms.

Remember, the voltage dropped across an inductor is a reaction against the change in

current through it. Therefore, the instantaneous voltage is zero whenever the

instantaneous current is at a peak (zero change, or level slope, on the current sine

wave), and the instantaneous voltage is at a peak wherever the instantaneous current is

at maximum change (the points of steepest slope on the current wave, where it crosses

the zero line). This results in a voltage wave that is 90o out of phase with the current

wave. Looking at the graph, the voltage wave seems to have a “head start” on the

current wave; the voltage “leads” the current, and the current “lags” behind the

voltage. (Figure below)

Current lags voltage by 90o in a pure inductive circuit.

Things get even more interesting when we plot the power for this circuit:

(Figure below)

In a pure inductive circuit, instantaneous power may be positive or negative

Because instantaneous power is the product of the instantaneous voltage and the

instantaneous current (p=ie), the power equals zero whenever the instantaneous

current or voltage is zero. Whenever the instantaneous current and voltage are both

positive (above the line), the power is positive. As with the resistor example, the

power is also positive when the instantaneous current and voltage are both negative

(below the line). However, because the current and voltage waves are 90o out of

phase, there are times when one is positive while the other is negative, resulting in

equally frequent occurrences of negative instantaneous power.

But what does negative power mean? It means that the inductor is releasing power

back to the circuit, while a positive power means that it is absorbing power from the

circuit. Since the positive and negative power cycles are equal in magnitude and

duration over time, the inductor releases just as much power back to the circuit as it

absorbs over the span of a complete cycle. What this means in a practical sense is that

the reactance of an inductor dissipates a net energy of zero, quite unlike the resistance

of a resistor, which dissipates energy in the form of heat. Mind you, this is for perfect

inductors only, which have no wire resistance.

An inductor's opposition to change in current translates to an opposition to alternating

current in general, which is by definition always changing in instantaneous magnitude

and direction. This opposition to alternating current is similar to resistance, but

different in that it always results in a phase shift between current and voltage, and it

dissipates zero power. Because of the differences, it has a different name:reactance.

Reactance to AC is expressed in ohms, just like resistance is, except that its

mathematical symbol is X instead of R. To be specific, reactance associate with an

inductor is usually symbolized by the capital letter X with a letter L as a subscript,

like this: XL.

Since inductors drop voltage in proportion to the rate of current change, they will drop

more voltage for faster-changing currents, and less voltage for slower-changing

currents. What this means is that reactance in ohms for any inductor is directly

proportional to the frequency of the alternating current. The exact formula for

determining reactance is as follows:

If we expose a 10 mH inductor to frequencies of 60, 120, and 2500 Hz, it will

manifest the reactances in Table Figure below.

Reactance of a 10 mH inductor:

Frequency (Hertz) Reactance (Ohms)

60 3.7699

120 7.5398

2500 157.0796

In the reactance equation, the term “2πf” (everything on the right-hand side except the

L) has a special meaning unto itself. It is the number of radians per second that the

alternating current is “rotating” at, if you imagine one cycle of AC to represent a full

circle's rotation. A radian is a unit of angular measurement: there are 2π radians in

one full circle, just as there are 360o in a full circle. If the alternator producing the AC

is a double-pole unit, it will produce one cycle for every full turn of shaft rotation,

which is every 2π radians, or 360o. If this constant of 2π is multiplied by frequency in

Hertz (cycles per second), the result will be a figure in radians per second, known as

the angular velocity of the AC system.

Angular velocity may be represented by the expression 2πf, or it may be represented

by its own symbol, the lower-case Greek letter Omega, which appears similar to our

Roman lower-case “w”: ω. Thus, the reactance formula XL = 2πfL could also be

written as XL = ωL.

It must be understood that this “angular velocity” is an expression of how rapidly the

AC waveforms are cycling, a full cycle being equal to 2π radians. It is not necessarily

representative of the actual shaft speed of the alternator producing the AC. If the

alternator has more than two poles, the angular velocity will be a multiple of the shaft

speed. For this reason, ω is sometimes expressed in units of electricalradians per

second rather than (plain) radians per second, so as to distinguish it from mechanical

motion.

Any way we express the angular velocity of the system, it is apparent that it is directly

proportional to reactance in an inductor. As the frequency (or alternator shaft speed) is

increased in an AC system, an inductor will offer greater opposition to the passage of

current, and vice versa. Alternating current in a simple inductive circuit is equal to the

voltage (in volts) divided by the inductive reactance (in ohms), just as either

alternating or direct current in a simple resistive circuit is equal to the voltage (in

volts) divided by the resistance (in ohms). An example circuit is shown here:

(Figure below)

Inductive reactance

However, we need to keep in mind that voltage and current are not in phase here. As

was shown earlier, the voltage has a phase shift of +90o with respect to the current.

(Figure below) If we represent these phase angles of voltage and current

mathematically in the form of complex numbers, we find that an inductor's opposition

to current has a phase angle, too:

Current lags voltage by 90o in an inductor.

Mathematically, we say that the phase angle of an inductor's opposition to current is

90o, meaning that an inductor's opposition to current is a positive imaginary quantity.

This phase angle of reactive opposition to current becomes critically important in

circuit analysis, especially for complex AC circuits where reactance and resistance

interact. It will prove beneficial to represent any component's opposition to current in

terms of complex numbers rather than scalar quantities of resistance and reactance.

REVIEW: Inductive reactance is the opposition that an inductor offers to alternating

current due to its phase-shifted storage and release of energy in its magnetic

field. Reactance is symbolized by the capital letter “X” and is measured in

ohms just like resistance (R).

Inductive reactance can be calculated using this formula: XL = 2πfL

The angular velocity of an AC circuit is another way of expressing its

frequency, in units of electrical radians per second instead of cycles per second.

It is symbolized by the lower-case Greek letter “omega,” or ω.

Inductive reactance increases with increasing frequency. In other words, the

higher the frequency, the more it opposes the AC flow of electrons.

Series resistor-inductor circuits

In the previous section, we explored what would happen in simple resistor-only and

inductor-only AC circuits. Now we will mix the two components together in series

form and investigate the effects.

Take this circuit as an example to work with: (Figure below)

Series resistor inductor circuit: Current lags applied voltage by 0o to 90o.

The resistor will offer 5 Ω of resistance to AC current regardless of frequency, while

the inductor will offer 3.7699 Ω of reactance to AC current at 60 Hz. Because the

resistor's resistance is a real number (5 Ω ∠ 0o, or 5 + j0 Ω), and the inductor's

reactance is an imaginary number (3.7699 Ω ∠ 90o, or 0 + j3.7699 Ω), the combined

effect of the two components will be an opposition to current equal to the complex

sum of the two numbers. This combined opposition will be a vector combination of

resistance and reactance. In order to express this opposition succinctly, we need a

more comprehensive term for opposition to current than either resistance or reactance

alone. This term is called impedance, its symbol is Z, and it is also expressed in the

unit of ohms, just like resistance and reactance. In the above example, the total circuit

impedance is:

Impedance is related to voltage and current just as you might expect, in a manner

similar to resistance in Ohm's Law:

In fact, this is a far more comprehensive form of Ohm's Law than what was taught in

DC electronics (E=IR), just as impedance is a far more comprehensive expression of

opposition to the flow of electrons than resistance is. Any resistance and any

reactance, separately or in combination (series/parallel), can be and should be

represented as a single impedance in an AC circuit.

To calculate current in the above circuit, we first need to give a phase angle reference

for the voltage source, which is generally assumed to be zero. (The phase angles of

resistive and inductive impedance arealways 0o and +90o, respectively, regardless of

the given phase angles for voltage or current).

As with the purely inductive circuit, the current wave lags behind the voltage wave (of

the source), although this time the lag is not as great: only 37.016o as opposed to a full

90o as was the case in the purely inductive circuit. (Figure below)

Current lags voltage in a series L-R circuit.

For the resistor and the inductor, the phase relationships between voltage and current

haven't changed. Voltage across the resistor is in phase (0o shift) with the current

through it; and the voltage across the inductor is +90o out of phase with the current

going through it. We can verify this mathematically:

The voltage across the resistor has the exact same phase angle as the current through

it, telling us that E and I are in phase (for the resistor only).

The voltage across the inductor has a phase angle of 52.984o, while the current

through the inductor has a phase angle of -37.016o, a difference of exactly

90o between the two. This tells us that E and I are still 90o out of phase (for the

inductor only).

We can also mathematically prove that these complex values add together to make the

total voltage, just as Kirchhoff's Voltage Law would predict:

Let's check the validity of our calculations with SPICE: (Figure below)

Spice circuit: R-L.

ac r-l circuit

v1 1 0 ac 10 sin

r1 1 2 5

l1 2 0 10m

.ac lin 1 60 60

.print ac v(1,2) v(2,0) i(v1)

.print ac vp(1,2) vp(2,0) ip(v1)

.end

freq v(1,2) v(2) i(v1)

6.000E+01 7.985E+00 6.020E+00 1.597E+00

freq vp(1,2) vp(2) ip(v1)

6.000E+01 -3.702E+01 5.298E+01 1.430E+02

Note that just as with DC circuits, SPICE outputs current figures as though they were

negative (180o out of phase) with the supply voltage. Instead of a phase angle of -

37.016o, we get a current phase angle of 143o (-37o + 180o). This is merely an

idiosyncrasy of SPICE and does not represent anything significant in the circuit

simulation itself. Note how both the resistor and inductor voltage phase readings

match our calculations (-37.02o and 52.98o, respectively), just as we expected them to.

With all these figures to keep track of for even such a simple circuit as this, it would

be beneficial for us to use the “table” method. Applying a table to this simple series

resistor-inductor circuit would proceed as such. First, draw up a table for E/I/Z figures

and insert all component values in these terms (in other words, don't insert actual

resistance or inductance values in Ohms and Henrys, respectively, into the table;

rather, convert them into complex figures of impedance and write those in):

Although it isn't necessary, I find it helpful to write both the rectangular and polar

forms of each quantity in the table. If you are using a calculator that has the ability to

perform complex arithmetic without the need for conversion between rectangular and

polar forms, then this extra documentation is completely unnecessary. However, if

you are forced to perform complex arithmetic “longhand” (addition and subtraction in

rectangular form, and multiplication and division in polar form), writing each quantity

in both forms will be useful indeed.

Now that our “given” figures are inserted into their respective locations in the table,

we can proceed just as with DC: determine the total impedance from the individual

impedances. Since this is a series circuit, we know that opposition to electron flow

(resistance or impedance) adds to form the total opposition:

Now that we know total voltage and total impedance, we can apply Ohm's Law

(I=E/Z) to determine total current:

Just as with DC, the total current in a series AC circuit is shared equally by all

components. This is still true because in a series circuit there is only a single path for

electrons to flow, therefore the rate of their flow must uniform throughout.

Consequently, we can transfer the figures for current into the columns for the resistor

and inductor alike:

Now all that's left to figure is the voltage drop across the resistor and inductor,

respectively. This is done through the use of Ohm's Law (E=IZ), applied vertically in

each column of the table:

And with that, our table is complete. The exact same rules we applied in the analysis

of DC circuits apply to AC circuits as well, with the caveat that all quantities must be

represented and calculated in complex rather than scalar form. So long as phase shift

is properly represented in our calculations, there is no fundamental difference in how

we approach basic AC circuit analysis versus DC.

Now is a good time to review the relationship between these calculated figures and

readings given by actual instrument measurements of voltage and current. The figures

here that directly relate to real-life measurements are those in polar notation, not

rectangular! In other words, if you were to connect a voltmeter across the resistor in

this circuit, it would indicate 7.9847 volts, not 6.3756 (real rectangular) or 4.8071

(imaginary rectangular) volts. To describe this in graphical terms, measurement

instruments simply tell you how long the vector is for that particular quantity (voltage

or current).

Rectangular notation, while convenient for arithmetical addition and subtraction, is a

more abstract form of notation than polar in relation to real-world measurements. As I

stated before, I will indicate both polar and rectangular forms of each quantity in my

AC circuit tables simply for convenience of mathematical calculation. This is not

absolutely necessary, but may be helpful for those following along without the benefit

of an advanced calculator. If we were to restrict ourselves to the use of only one form

of notation, the best choice would be polar, because it is the only one that can be

directly correlated to real measurements.

Impedance (Z) of a series R-L circuit may be calculated, given the resistance (R) and

the inductive reactance (XL). Since E=IR, E=IXL, and E=IZ, resistance, reactance, and

impedance are proportional to voltage, respectively. Thus, the voltage phasor diagram

can be replaced by a similar impedance diagram. (Figure below)

Series: R-L circuit Impedance phasor diagram.

Example:

Given: A 40 Ω resistor in series with a 79.58 millihenry inductor. Find the impedance

at 60 hertz.

XL = 2πfL

XL = 2π·60·79.58×10-3

XL = 30 Ω

Z = R + jXL

Z = 40 + j30

|Z| = sqrt(402 + 302) = 50 Ω

∠Z = arctangent(30/40) = 36.87o

Z = 40 + j30 = 50∠36.87o

REVIEW: Impedance is the total measure of opposition to electric current and is the

complex (vector) sum of (“real”) resistance and (“imaginary”) reactance. It is

symbolized by the letter “Z” and measured in ohms, just like resistance (R) and

reactance (X).

Impedances (Z) are managed just like resistances (R) in series circuit analysis:

series impedances add to form the total impedance. Just be sure to perform all

calculations in complex (not scalar) form! ZTotal = Z1 + Z2 + . . . Zn

A purely resistive impedance will always have a phase angle of exactly

0o (ZR = R Ω ∠ 0o).

A purely inductive impedance will always have a phase angle of exactly

+90o (ZL = XL Ω ∠ 90o).

Ohm's Law for AC circuits: E = IZ ; I = E/Z ; Z = E/I

When resistors and inductors are mixed together in circuits, the total impedance

will have a phase angle somewhere between 0o and +90o. The circuit current

will have a phase angle somewhere between 0o and -90o.

Series AC circuits exhibit the same fundamental properties as series DC

circuits: current is uniform throughout the circuit, voltage drops add to form the

total voltage, and impedances add to form the total impedance.

Parallel resistor-inductor circuits

Let's take the same components for our series example circuit and connect them in

parallel: (Figure below)

Parallel R-L circuit.

Because the power source has the same frequency as the series example circuit, and

the resistor and inductor both have the same values of resistance and inductance,

respectively, they must also have the same values of impedance. So, we can begin our

analysis table with the same “given” values:

The only difference in our analysis technique this time is that we will apply the rules

of parallel circuits instead of the rules for series circuits. The approach is

fundamentally the same as for DC. We know that voltage is shared uniformly by all

components in a parallel circuit, so we can transfer the figure of total voltage (10 volts

∠ 0o) to all components columns:

Now we can apply Ohm's Law (I=E/Z) vertically to two columns of the table,

calculating current through the resistor and current through the inductor:

Just as with DC circuits, branch currents in a parallel AC circuit add to form the total

current (Kirchhoff's Current Law still holds true for AC as it did for DC):

Finally, total impedance can be calculated by using Ohm's Law (Z=E/I) vertically in

the “Total” column. Incidentally, parallel impedance can also be calculated by using a

reciprocal formula identical to that used in calculating parallel resistances.

The only problem with using this formula is that it typically involves a lot of

calculator keystrokes to carry out. And if you're determined to run through a formula

like this “longhand,” be prepared for a very large amount of work! But, just as with

DC circuits, we often have multiple options in calculating the quantities in our

analysis tables, and this example is no different. No matter which way you calculate

total impedance (Ohm's Law or the reciprocal formula), you will arrive at the same

figure:

REVIEW: Impedances (Z) are managed just like resistances (R) in parallel circuit

analysis: parallel impedances diminish to form the total impedance, using the

reciprocal formula. Just be sure to perform all calculations in complex (not

scalar) form! ZTotal = 1/(1/Z1 + 1/Z2 + . . . 1/Zn)

Ohm's Law for AC circuits: E = IZ ; I = E/Z ; Z = E/I

When resistors and inductors are mixed together in parallel circuits (just as in

series circuits), the total impedance will have a phase angle somewhere

between 0o and +90o. The circuit current will have a phase angle somewhere

between 0o and -90o.

Parallel AC circuits exhibit the same fundamental properties as parallel DC

circuits: voltage is uniform throughout the circuit, branch currents add to form

the total current, and impedances diminish (through the reciprocal formula) to

form the total impedance.

Inductor quirks

In an ideal case, an inductor acts as a purely reactive device. That is, its opposition to

AC current is strictly based on inductive reaction to changes in current, and not

electron friction as is the case with resistive components. However, inductors are not

quite so pure in their reactive behavior. To begin with, they're made of wire, and we

know that all wire possesses some measurable amount of resistance (unless its

superconducting wire). This built-in resistance acts as though it were connected in

series with the perfect inductance of the coil, like this: (Figure below)

Inductor Equivalent circuit of a real inductor.

Consequently, the impedance of any real inductor will always be a complex

combination of resistance and inductive reactance.

Compounding this problem is something called the skin effect, which is AC's tendency

to flow through the outer areas of a conductor's cross-section rather than through the

middle. When electrons flow in a single direction (DC), they use the entire cross-

sectional area of the conductor to move. Electrons switching directions of flow, on the

other hand, tend to avoid travel through the very middle of a conductor, limiting the

effective cross-sectional area available. The skin effect becomes more pronounced as

frequency increases.

Also, the alternating magnetic field of an inductor energized with AC may radiate off

into space as part of an electromagnetic wave, especially if the AC is of high

frequency. This radiated energy does not return to the inductor, and so it manifests

itself as resistance (power dissipation) in the circuit.

Added to the resistive losses of wire and radiation, there are other effects at work in

iron-core inductors which manifest themselves as additional resistance between the

leads. When an inductor is energized with AC, the alternating magnetic fields

produced tend to induce circulating currents within the iron core known as eddy

currents. These electric currents in the iron core have to overcome the electrical

resistance offered by the iron, which is not as good a conductor as copper. Eddy

current losses are primarily counteracted by dividing the iron core up into many thin

sheets (laminations), each one separated from the other by a thin layer of electrically

insulating varnish. With the cross-section of the core divided up into many electrically

isolated sections, current cannot circulate within that cross-sectional area and there

will be no (or very little) resistive losses from that effect.

As you might have expected, eddy current losses in metallic inductor cores manifest

themselves in the form of heat. The effect is more pronounced at higher frequencies,

and can be so extreme that it is sometimes exploited in manufacturing processes to

heat metal objects! In fact, this process of “inductive heating” is often used in high-

purity metal foundry operations, where metallic elements and alloys must be heated in

a vacuum environment to avoid contamination by air, and thus where standard

combustion heating technology would be useless. It is a “non-contact” technology, the

heated substance not having to touch the coil(s) producing the magnetic field.

In high-frequency service, eddy currents can even develop within the cross-section of

the wire itself, contributing to additional resistive effects. To counteract this tendency,

special wire made of very fine, individually insulated strands called Litz wire (short

for Litzendraht) can be used. The insulation separating strands from each other

prevent eddy currents from circulating through the whole wire's cross-sectional area.

Additionally, any magnetic hysteresis that needs to be overcome with every reversal

of the inductor's magnetic field constitutes an expenditure of energy that manifests

itself as resistance in the circuit. Some core materials (such as ferrite) are particularly

notorious for their hysteretic effect. Counteracting this effect is best done by means of

proper core material selection and limits on the peak magnetic field intensity

generated with each cycle.

Altogether, the stray resistive properties of a real inductor (wire resistance, radiation

losses, eddy currents, and hysteresis losses) are expressed under the single term of

“effective resistance:” (Figure below)

Equivalent circuit of a real inductor with skin-effect, radiation, eddy current, and

hysteresis losses.

It is worthy to note that the skin effect and radiation losses apply just as well to

straight lengths of wire in an AC circuit as they do a coiled wire. Usually their

combined effect is too small to notice, but at radio frequencies they can be quite large.

A radio transmitter antenna, for example, is designed with the express purpose of

dissipating the greatest amount of energy in the form of electromagnetic radiation.

Effective resistance in an inductor can be a serious consideration for the AC circuit

designer. To help quantify the relative amount of effective resistance in an inductor,

another value exists called the Q factor, or “quality factor” which is calculated as

follows:

The symbol “Q” has nothing to do with electric charge (coulombs), which tends to be

confusing. For some reason, the Powers That Be decided to use the same letter of the

alphabet to denote a totally different quantity.

The higher the value for “Q,” the “purer” the inductor is. Because its so easy to add

additional resistance if needed, a high-Q inductor is better than a low-Q inductor for

design purposes. An ideal inductor would have a Q of infinity, with zero effective

resistance.

Because inductive reactance (X) varies with frequency, so will Q. However, since the

resistive effects of inductors (wire skin effect, radiation losses, eddy current, and

hysteresis) also vary with frequency, Q does not vary proportionally with reactance. In

order for a Q value to have precise meaning, it must be specified at a particular test

frequency.

Stray resistance isn't the only inductor quirk we need to be aware of. Due to the fact

that the multiple turns of wire comprising inductors are separated from each other by

an insulating gap (air, varnish, or some other kind of electrical insulation), we have

the potential for capacitance to develop between turns. AC capacitance will be

explored in the next chapter, but it suffices to say at this point that it behaves very

differently from AC inductance, and therefore further “taints” the reactive purity of

real inductors.

More on the “skin effect”

As previously mentioned, the skin effect is where alternating current tends to avoid

travel through the center of a solid conductor, limiting itself to conduction near the

surface. This effectively limits the cross-sectional conductor area available to carry

alternating electron flow, increasing the resistance of that conductor above what it

would normally be for direct current: (Figure below)

Skin effect: skin depth decreases with increasing frequency.

The electrical resistance of the conductor with all its cross-sectional area in use is

known as the “DC resistance,” the “AC resistance” of the same conductor referring to

a higher figure resulting from the skin effect. As you can see, at high frequencies the

AC current avoids travel through most of the conductor's cross-sectional area. For the

purpose of conducting current, the wire might as well be hollow!

In some radio applications (antennas, most notably) this effect is exploited. Since

radio-frequency (“RF”) AC currents wouldn't travel through the middle of a conductor

anyway, why not just use hollow metal rods instead of solid metal wires and save both

weight and cost? (Figure below) Most antenna structures and RF power conductors

are made of hollow metal tubes for this reason.

In the following photograph you can see some large inductors used in a 50 kW radio

transmitting circuit. The inductors are hollow copper tubes coated with silver, for

excellent conductivity at the “skin” of the tube:

The Electrodermal Response

27.1 INTRODUCTION

In previous chapters we described the need to take into account the interaction of

the skin with electrodes whose purpose it was to record the surface potential

noninvasively or to introduce stimulating currents. The skin and its properties were

usually seen in these examples as providing certain difficulties to be understood and

counteracted. In this chapter the sphere of interest is the skin response itself.

Interest in the conductance between skin electrodes, usually placed at the

palmar surface, arose because of the involvement of the sweat glands in this

measurement. Since sweat gland activity, in turn, is controlled by sympathetic nerve

activity, this measurement has been considered as an ideal way to monitor the

autonomic nervous system. In this chapter we describe what is currently understood

to underlie the electrodermal response (EDR) to sympathetic stimulation. The source

of the material for this chapter comes mainly from the summary papers of Fowles

(1974, 1986) and Venables and Christie (1980) which are suggested as the first

recourse of the reader seeking further information.

In the earlier chapters of this book such topics have been chosen that illustrate

the fundamental principles of this discipline. In this chapter we discover that the

basis for the EDR is not well understood and much remains to be discovered to

explain the phenomena in basic physiological and biophysical terms. In spite of this

shortcoming EDR is nevertheless widely used. Since it is a topic in bioelectricity it

deserves attention precisely because of the need for further study. Clearly, here is a

bioelectromagnetic application where a valid quantitative model would have an

immediate and salutary effect on its use in research and in clinical applications.

27.2 PHYSIOLOGY OF THE SKIN

The interpretation of skin conductance and/or skin potential requires some

understanding about the structure of tissues at and beneath the skin surface. Figure

27.1 shows the main features of the skin. The most superficial layer is called

the epidermis and consists of the stratum corneum, the stratum lucidum (seen only

on "frictional surfaces"), the granular layer, the prickle cell layer, and

the basal orgerminating layer. The surface of the corneum (i.e., surface of the skin) is

composed of dead cells, while at its base one finds healthy, living cells. Between

these two sites there are transitional cells. This layer is also called the horny layer.

Blood vessels are found in the dermis whereas the eccrine sweat gland secretory

cells are found at the boundary between the dermis and the panniculus adiposus,

also referred to as hypodermis and superficial fascia. The excretory duct of the

eccrine sweat glands consists of a simple tube made up of a single or double layer of

epithelial cells; this ascends to and opens on the surface of the skin. It is undulating

in the dermis but then follows a spiral and inverted conical path through the

epidermis to terminate in a pore on the skin surface. Cholinergic stimulation via

fibers from the sympathetic nervous system constitutes the major influence on the

production of sweat by these eccrine glands.

From an examination of Figure 27.1 one can appreciate that the epidermis

ordinarily has a high electrical resistance due to the thick layer of dead cells with

thickened keratin membranes. This aspect is not surprising, since the function of skin

is to provide a barrier and protection against abrasion, mechanical assaults, and so

on. The entire epidermis (with the exception of the desquamating cells) constitutes

thebarrier layer), a permeability barrier to flow. Experiments show its behavior to be

that of a passive membrane.

However, the corneum is penetrated by the aforementioned sweat ducts from

underlying cells; as these ducts fill, a relatively good conductor (sweat can be

considered the equivalent of a 0.3% NaCl salt solution and, hence, a weak

electrolyte) emerges, and many low-resistance parallel pathways result. A further

increase in conductance results from the hydration of the corneum due to the flow

of sweat across the duct walls (a process that is facilitated by the corkscrew duct

pathway and the extremely hydrophilic nature of the corneum). As a consequence

the effective skin conductance can vary greatly, depending on present and past

eccrine activity. The aforementioned behavior is particularly great in the palmar and

plantar regions because while the epidermis is very thick, at the same time the

eccrine glands are unusually dense. It should be noted that the loading of ducts with

sweat can be taking place before any (observable) release of sweat from the skin

surface and/or noticeable diffusion into the corneum.

We have noted that the main function of the skin is to protect the body from

the environment. One aspect of this is to prevent the loss of water by the body.

However, at the same time, the evaporation of water as a means of regulating body

temperature must be facilitated. These requirements appear to be carried out by the

stratum corneum as a barrier layer that prevents the loss of water to the outside

except through the sweat glands, whose activity can be controlled. This in turn is

mediated by the autonomic (sympathetic) nervous system. Measurement of the

output of the sweat glands, which EDR is thought to do, provides a simple gauge of

the level and extent of sympathetic activity. This is the simple and basic concept

underlying EDR and its application to psychophysiology.

Fig. 27.1 Section of smooth skin taken from the sole of the foot. Blood vessels

have been injected. (Redrawn from Ebling, Eady, and Leigh, 1992.)

27.3 ELECTRODERMAL MEASURES

That the electrodermal response is associated with sweat gland activity is well

established. Convincing evidence arises from experiments in which a direct

correlation is seen between EDR and stimulated sweat gland activity. Furthermore,

when sweat gland activity is abolished, then there is an absence of EDR signals

(Fowles, 1986).

There are two major measures of the electrodermal response. The first,

involving the measurement of resistance or conductance between two electrodes

placed in the palmar region, was originally suggested by Féré (1888). It is possible

also to detect voltages between these electrodes; these potential waveforms appear

to be similar to the passive resistance changes, though its interpretation is less well

understood. This measurement was pioneered by Tarchanoff (1889). The first type of

measurement is referred to as exosomatic, since the current on which the

measurement is based is introduced from the outside. The second type, which is less

commonly used, is called endosomatic, since the source of voltage is internal.

Researchers also distinguish whether the measurement is of the (tonic) background

level (L), or the time-varying (phasic) response (R) type. These simple ideas have led

to a number of specific measures, each described by a three letter-abbreviation.

These are listed in Table 27.1.

Table 27.1. Abbreviations used to distinguish the type of

electrodermal measurements

Abbreviation Significance

EDA Electrodermal Activity

EDL Electrodermal Level

EDR Electrodermal

Response

SCL Skin Conductance

Level

SCR Skin Conductance

Response

SRL Skin Resistance Level

SRR Skin Resistance

Response

SPL Skin Potential Level

SPR Skin Potential

Response

Older terminology no longer in use, such as the galvanic skin response, has not

been included in the table. The resistance and conductance measurements are

reciprocals, of course; however, one or the other might turn out to be linearly related

to the stimuli under study and be somewhat more useful as a result.

27.4 MEASUREMENT SITES AND CHARACTERISTIC SIGNALS

As discussed above, EDA is best measured at palmar sites. Suggested locations for

electrode placement are given in Figure 27.2. In general, the electrodes used are of

the Ag/AgCl type which are recessed from the skin and require the use of a suitable

electrode paste. Since this is a reversible type of electrode, polarization and bias

potentials are minimized. This is obviously of importance since such contributions

introduce artifact in the SP and SC determinations. There is also a half-cell potential

under each electrode, but if these are similar and overlie identical chloride

concentrations their effects are equal and cancel. For this reason an electrode paste

with NaCl at the concentration of sweat (approximately 0.3% NaCl) is to be

preferred.

As described in Figure 27.2, the reference site should be abraded, a procedure

that may possibly remove the corneum and introduce much reduced contact

resistance. The site itself, on the forearm, is selected to be a neutral (nonactive)

location so that only good contact is required. Although the removal of the corneum

at the active site would interfere with the examination of the system there, no such

requirement needs to be imposed at the reference site, since it should be nonactive.

Fig. 27.2 Suggested electrode sites on the palm for the measurement of skin

resistance and skin potentials. (Redrawn from Venables and Christie, 1980.)

Shown in Figure 27.3 are signals characteristic of SCR and SPR waveforms.

Those identified as having slow recovery, shown in Figure 27.3A, have a duration of

around 40 s, with phasic amplitudes of around 2 µS for conductance and 10-20 mV

for potential. Since the amplitude values depend on electrode area in a nonlinear way,

these values cannot be readily normalized and, consequently, are difficult to compare

with others. Data collected by Venables and Christie (1980) give a mean SCL of 0.3

µS and SCR of 0.52 µS in a study of a particular population (N = 500-600). Rapid-

recovery SCRs and SPRs are shown in Figure 27.3B.

The electronics associated with measurement of EDR is fairly simple. For

exosomatic conditions either a constant current or a constant voltage source is used.

As illustrated by Venables and Christie (1980), the circuit in either case consists of a

battery with voltage EB connected to the skin through a series resistance RA; the

circuit is completed by the skin resistance Rs. Constant current conditions can be

implemented by letting RA be very large. (In the example given, EB = 100 V; RA = 10

MΩ; and, even for high values of skin resistance (i.e., , corresponding to

4 µS), the current differs from a nominal 10.0 µA by under 2.5%.) For constant-

voltage conditions RA is small compared to Rs, so the voltage across Rs is the fixed

battery voltage. In the constant-current case, the skin voltage Vs(t) is measured and

(27.1)

For constant-voltage conditions the voltage VA is measured across the series

resistance. Then

(27.2)

Present-day practice utilizes a battery voltage Eb of 0.5 V, whereas constant current

and constant voltage are better obtained electronically.

For endosomatic measurements the skin potential is desired, and the optimum

condition is where the input resistance of the amplifier is very high compared to the

skin resistance. The use of an operational amplifier is called for. Additional

requirements are evident from the sample waveforms in Figure 27.3: in general, an

input voltage in the range of +10 to -70 mV at a bandwidth of from DC to a few Hz.

Geddes and Baker (1989) suggest 0-5 Hz for tonic measurements, with 0.03-5 Hz

being adequate for phasic measurements. Recommendations for electrodermal

measurements were drawn up by a committee selected by the editor

of Psychophysiology and published by that journal (Fowles et al., 1981). The paper by

MacPherson, MacNeil, and Marble (1976) on measurement devices may also be

useful.

Fig. 27.3 (A) Upper trace is a slow-recovery SCR, whereas middle and lower

are monophasic negative SPRs.

(B) The upper trace is a rapid-recovery SCR, whereas the middle and lower

traces are positive monophasic SPRs. (Redrawn from Fowles, 1974.)

27.5 THEORY OF EDR

A comprehensive model underlying EDR has been developed by Fowles (1974) and

appears essentially unchanged in Fowles (1986); its principle is given here in Figure

27.4. This model is useful only in a qualitative sense since there is no quantitative

data either to support the circuit or to provide an evaluation of any of its elements.

The top of the figure represents the surface of the skin, whereas the bottom

represents the interface between the hypodermis and the dermis. The active

electrode is at the top (skin surface), whereas the reference electrode is consired to

be at the bottom (hypodermis).

R1 and R2 represent the resistance to current flow through the sweat ducts

located in the epidermis and dermis, respectively. These are major current flow

pathways when these ducts contain sweat, and their resistance decreases as the

ducts fill. Such filling starts in the dermis and continues into the epidermis.

E1 and R4 represent access to the ducts through the duct wall in the dermis,

whereas E2 and R3 describe the same pathway, but in the epidermis. Transduct

potentials E1 and E2 arise as a result of unequal ionic concentrations across the duct

as well as selective ionic permeabilities (as discussed in Chapter 3). This potential is

affected by the production of sweat, particularly if, as is thought, the buildup of

hydrostatic pressure results in depolarization of the ductal membranes. Such

depolarization results in increased permeability to ion flow; this is manifested in the

model by decreased values of R3 and R4. In particular, this is regarded as an

important mechanism to explain rapid-recovery signals (since the restoration of

normal permeability is equally fast). The potentials of E1 and E2 are normally lumen-

negative.

The resistance R5 is that of the corneum, whereas E3 is its potential (treating

this region as the site of liquid junction potentials). The phenomenon of hydration of

the corneum, resulting from the diffusion of sweat from the sweat ducts into the

normally dry and absorbant corneum, leads to a reduction in the value of R5.

The predicted outcome of an experiment depends on (among others) the size

of the response to a stimulus and the prior sweat gland condition. For an SCR

determination Fowles (1986) states that the potentials can be ignored (these appear

to be relatively small factors). If one assumes initial resting conditions, then a sweat

response consists of sweat rising in the ducts, and correspondingly R2 slowly

diminishes. The response latency is associated with the time required for this to take

place. If the response is a small one and R1 and R5 are not affected, then the SCR may

not show any change. For a larger response, although sweat still remains within the

ducts, it now extends also into the corneum and hence reduces R1 as well as R2. If it

is large enough, then flow across the duct wall will take place, causing hydration of

the corneum and a decrease in R5. With a very large sweat response (or if a

moderate response takes place after the ducts are already partly filled), then the

response also includes the triggering of the epidermal duct membrane due to

associated hydrostatic pressure buildup, and a consequent reduction of R3.

For SP recordings Figure 27.4 can also serve as a guide on the possible outcome

of the response to a stimulus. The measured potential is thought to represent,

mainly, that across the epidermis - namelyE3 minus the voltage drop in R5. Factors

that are considered include the reabsorption of sodium across the duct walls by

active transport which generates large lumen-negative potentials. Their effect on the

measured potentials depends on the relative values of R1, R2, and R4 (with low values

enhancing surface measurement of E1, and low R5 values diminishing this

measurement (Edelberg, 1968)). With modest responses when the corneum is

relatively unhydrated, the increased lumen-negative duct potential and decrease

in R2 and possibly R1 act to produce a monophasic negative SPR. Large responses that

trigger the membrane response and a large and rapid decrease in R3 result in a

decrease in the measured negative potential and possibly a positive component if

the ducts are already filled.

The reader can appreciate that the model is not a quantitative one and, hence,

cannot be appealed to as a source of information regarding the outcome of an

experiment except in very qualitative terms. One needs to examine to what extent a

lumped- parameter circuit can represent the actual distributed system. Possibly such

a circuit is justifiable; perhaps additional layers are needed. Most importantly, each

circuit element needs to be described biophysically and quantitatively. Presumably

this will require isolation of different parts of the system and also appropriate in vitro

experiments. In the meantime, EDA appears to be useful as an empirical tool for

registering the level of sympathetic activity in a psychophysiological experiment.

One problem in the use of EDR should be mentioned. When skin conductance

responses are used to evaluate an immediate outcome to a specific stimulus, it can

be difficult to distinguish the stimulus specific response from the spontaneous SCR

activity. To deal with this problem, investigators use a response window of 1-5 s

following the stimulus, during which a signal will be accepted. If one assumes a

spontaneous SCR rate of 7.5/min, the reduction in a confounding spontaneous SCR is

50%. A narrower window has been suggested to discriminate further against the

unwanted signal.

Fig. 27.4 A simplified equivalent circuit describing the electrodermal system.

Components are identified in the text. (From Fowles, 1986.)

27.6 APPLICATIONS

The applications of EDR lie in the area of psychophysiology and relate to studies in

which a quantitative measure of sympathetic activity is desired. Fowles (1986)

states:

The stimuli that elicit these [EDA] responses are so ubiquitous that it has

proved difficult to offer a conceptualization of the features common to these

stimuli. There is no doubt, however, that the response often occurs to stimuli

that depend for their efficacy on their physiological significance as opposed to

their physical intensity.

One measure of the extent of interest in EDR is the references to papers that

list EDR as a keyword. In the SCI's Citation Index for 1991, one finds approximately 25

such references (i.e., publications). The importance attached to such measurements

includes the statement in one recent paper that palmar sweat is one of the most

salient symptoms of an anxiety state and, for some, the single most noticeable bodily

reaction. But such applications lie outside the scope of this book, and we shall not

pursue this topic further. The interested reader may wish to consult issues of the

journal Psychophysiology for many of the current research papers.

REFERENCES

Ebling FJG, Eady RAJ, Leigh IM (1992): Anatomy and organization of the human skin. In Textbook of

Dermatology, 5th ed., ed. RH Champion, JL Burton, FJG Ebling, p. 3160, Blackwell, London.

Edelberg R (1968): Biopotentials from the skin surface: The hydration effect. Ann. N.Y. Acad. Sci. 148: 252-62.

Féré C (1888): Note sur les modifications de la résistance électrique sous l'influence des excitations sensorielles et

des émotions. C. R. Soc. Biol. (Paris) 5: 217-9.

Fowles DC (1974): Mechanisms of electrodermal activity. In Methods in Physiological Psychology. Bioelectric

Recording Techniques, C ed. Vol. 1, ed. RF Thompson, MM Patterson, pp. 231-71, Academic Press, New York.

Fowles DC, Christie MJ, Edelberg R, Grings WW, Lykken DT, Venables PH (1981): Committee report: Publication

recommendations for electrodermal measurements. Psychophysiol. 18: 232-9.

Fowles DC (1986): The eccrine system and electrodermal activity. In Psychophysiology, ed. MGH Coles, E Donchin,

SW Porges, pp. 51-96, Guilford Press, New York.

Geddes LA, Baker LE (1989): Principles of Applied Biomedical Instrumentation, 3rd ed., John Wiley, New York,

N.Y.

MacPherson RD, MacNeil G, Marble AE (1976): Integrated circuit measurement of skin conductance. Behav. Res.

Methods Instrum. 8: 361-4.

Tarchanoff J (1889): Décharges électriques dans la peau de l'homme sous l'influence de l'excitation des organes des

sens et de différentes formes d'activité psychique. C. R. Soc. Biol. (Paris) 41: 447-51.

Venables PH, Christie MJ (1980): Electrodermal activity. In Techniques in Psychophysiology, ed. I Martin, PH

Venables, pp. 2-67, John Wiley, New York.

Electrical Measures of the Body

So with some simple science taught in our schools let us analyze the development of biology.

First our fifth grade science tells us we are mostly electro-magnetic-static and Quantic fields. Non-

living things mostly obey the laws of thermodynamics. The laws of thermodynamics teach us that

energy can not be created or destroyed, and that heat must flow from a hot body to a cold body. The

hot coffee must succumb to the colder room and the two gradually equate their temperature.

Biological systems outwardly seem to disobey these laws by maintaining a temperature

difference and not succumbing to the room temperature unless the die. Then as the Washington Post

editor says, after death they lose their battle with room temperature. Biology is using a slightly

different system of laws with a more quantic system than thermodynamic. REF PROMORPHEUS.

A living thing must be able to metabolize and reproduce in some fashion to be considered

alive. Metabolism is taking in nutrients, taking the energy from them, and excreting the remainder as

excretions of waste products. Reproduction is assembling new tissue for repair and also to propagate

the species. The energy is Quantic electro-magnetic-static in nature as is everything. The basic energy

of the electromagnetic radiation that is Visible light or Infrared heat. Plants take in low energy ionic

bound minerals and use the energy of visible light to make high energy covalent bound plant

compounds which are then food for the animals. This is the process of photosynthesis as shown in the

Calvin Cycle.

Animals take in the high energy compounds with electrons in high energy states. This energy

is then gleaned in the cells via the Krebs Cycle to make ATP (Adenosine Tri-Phosphate) for energy.

ATP is the key energy of most life.

The single cell systems such as bacteria set up a boundary layer such as a cell membrane to

separate the thermodynamic world from the quantic interior. Entropy and thermodynamics dictate

process in the non-living exterior versus the Quantic organized non random entropy interior.

Metabolism and reproduction guided by a organized accounting of energy intake and outgo. Geared for

metabolism and reproduction. Quantic Electromagnetic fields in cyclic organized fashion that is mostly

dependent on the Quantic actions of DNA. DNA can only be described in the Quantic electromagnetic

actions of the fields of it voltammetric structure.

Single celled organisms develop or evolve if you will allow us to say into multi celled

organisms. This needs more complex DNA structures and the number of chromosomes needed grows.

DNA acts as the chief accountant as it sends off RNA and messenger RNA to accomplish the goals of

life. Life develops with tremendous diversification over 100,000,000 organisms have evolved with

various and diverse functions. But all are Quantic electromagnetic exchange devices taking in energy,

excreting waste products, and trying to reproduce. Everything having it’s own set of field intricacies,

and a single reactive ever changing overall field signature. The Quantic Electro-magnetic-static field of

an organism is reacting towards nutrition and away from toxins. To maximize metabolism. It reacts to

mating signals and reproductive gesticulations to maximize reproduction.

Everything is a wash of field interactions and electromagnetic radiation photons. The cells of

biology use this electromagnetic radiation for communication. Information for reproduction or

Mitogenic radiation is in the visible, metabolism radiation is in the Infrared. Biology does not just send

heat out as a waste product it is a communication network for cellular info exchange.

The multi-celled organisms diversify and all have an innate non-verbal Quantic electro-

magnetic drive for survival. Biology operates thru field interactions. The height of DNA diversification

is presently the development of a word are of the brain. And are where we think in words. This allows

for explicit communication and exchange of thoughts, feelings, desire, fears, etc.

The Human Body Electric

There are over one hundred trillion cells in the human body and all are sending signals to the

brain via enervation and photon exchange. Making some ten to the 16 bits of data a sec. Or less.

1,000,000,000,000,000. The word area of the brain has developed as a small part of the human brain.

About the size of a golf ball this Broca area is for words. Words coming in and words going out. The

rest of the Brain is for life, metabolism and reproduction. Life is an unconscious process. Life is non-

verbal. We do not have to think words to live. Words are for helping us function in social ways.

We have a reticular formation in the base of our brains that act as a filter to screen out

unneeded data from our word area. The word area has the ability to assay about one million

1,000,000 bits of data at a time. More and the word area goes into overload. Below one thousand

sensory bits and the system goes into sensory deprivation mode. It invents sensory data.

This means that ten to the sixteenth bits of data minus the ten to the 6 bits of data for the

word area and the word are of the brain gets one percent of one percent of one percent of one percent

of one percent of one percent of one percent of one percent of one percent of one percent of one

percent of the data sent to the brain. The unconscious non-verbal body electric gets all of this data

and much more.

The spiritual cultures of the world know this and all exercises in spiritual development revolve

around diminishing the words in the brain and coming aware more of the unconscious process.

Mantras, meditation, stillness, yoga, kundalini, and many others all say we must control and diminish

to effects of the verbal word mind to get in touch with our body energetic. The true self.

Much of the mistake of modern science and modern societies is to over value the words and

the verbal process. Our society is presently over valuing the paper pushers and letting their need for

words be more important than people. We need paper pushers and we need to have quality systems

but there should be a requirement to try to minimize the over wordy and clarify the process of our

society for everyone to understand not just the small minded paper pushers. This is especially true for

biology and medicine.

The very process of life in an innate unconscious non-verbal Quantic electromagnet field

interaction. Words have little to do with it. But so-called modern medicine has overvalued the words.

They wait for the patient to verbally notice something is wrong, go to the doctor office and announce

what is wrong, answer the doctors’ verbal questions, and receive verbal instruction. And yet this

verbal exercise of medicine is only aware of one percent of one percent of one percent of one percent

of one percent of one percent of one percent of one percent of one percent of one percent of one

percent of the data. The body electric knows much more.

Patients words are influenced by their mood state. Patient’s all lie, at least that is what Dr.

House tells us on TV. Patients sometimes say things they think the doctor wants to hear, they coverup

things they don’t want the doctor to know and very often they are completely out of touch with their

own feelings and symptoms. Once I asked a patient if they had regular bowel movements. She said of

course once a week like clockwork. Words are often the only intervention given to a doctor. In ancient

China the doctor was sometimes unable to see the patient if he was royal. So the Chinese doctors had

to develop new skills. Words have been a hallmark of medicine but it is also one of the greatest

limitations. You can be really sick and have no symptoms or any verbal awareness of your sickness.

Many people have tended to not only over value words, but some assume falsely there is only words.

Now as we learned in 5th grade everything is made mostly of electrons and protons. Photons are

involved in all exchange of energy states. Now in some materials the electrons are tightly bound and

are unwilling to allow electron exchange. In concrete the atoms are bound tightly and the electrons

are not very conductive. In a metal like copper the electrons are quite willing to allow electro energy

exchange and transport of electrons. So copper is a good conductor.

The organization of atoms and electrons determines the nature of the substance. Atoms seek

to have a balanced outer level of electrons as per quantum law. This is the nature of atoms and it is

calculated in the mendeleev table of elements. Atoms seek to find the balance of the noble elements.

This is the lesson from 10th grade chemistry. It is a simple lesson that tells us just how all atoms

combine to make molecules. This lesson is based in Quantum theory. Those to say that quantum

theory is not relevant to biology are expressing a rather concerning ignorance.

Molecules can be very very complex. But all of them are made of electrons, protons, neutrons

etc held by Quantic forces. These molecules all have a structure of their outer electrons that can be

assayed by the voltammetric signature. Voltammetry is the science of electrodes checking the

individual style of electron and proton interaction. This is how every substance reacts to another, the

outer electrons never touch but the field interaction as determined by voltammetry is a definition of

how they work.

Every atom or molecule can be balanced, positive charge, negative charge, or combination of

both. This depends on the amount of protons and electrons. This is Basic grade school science.

The charged particles that travel make a current flow. The amount of charged particles in the

amperage, the pressure or potential of the flow is the voltage, the resistance to the flow is the

resistance. All organisms use this electrical flow of charged particles for each and every biological

process.

The electron is the smallest charged particle to move, and most of electricity is of the traveling

electron. But protons and ions range from the small to very large.

The outer electrons of a plant are taken to higher energy states thru the QED phenomena

known as photosynthesis. These electrons are most often stored in carbohydrates and natural sugars.

The body use them for energy, making ATP from the electrons.

Energy transfer in the body takes place in many voltammetric ways. Water has free protons

and free electrons and thus it is essential for life. Water does not conduct electricity, unless there are

some mineral salts or electrolytes in the water. But as in the salt water the body has lots of water and

electrolytes. Thus the body electric can thrive. REF

Fish like the shark swim and thus live in an electrolyte conductive medium. They develop

electrical sensing systems, and can detect foods by their voltammetric signatures. In other land

creatures like humans this electro sense is transferred to the skin and nose. But still voltammetric

sensing of items are the basis for life. REF

We have the sense of sight for photon sensing, hearing for sound vibration detection, feeling

for movement, pressure, heat, cold, balance, and the alkaline acid balance of chemicals. Smell and

taste are voltammetric shape receptors sensors. REF 2004 Nobel prize. And the electro sense. The

largest gene family of our DNA is dedicated to the smell, over 3% in humans, 7% in some animals. All

of our senses are electrical in action and transfer mechanism. Some of our sensory system is directed

to our verbal or conscious mind and most to our non-verbal unconscious.

In the human body there is massive transfer of electrical signals. The flow of food entering the

colon during digestion is based on static electrical attraction. Water facilitates the entire body electric.

The body heat is photonic and also contributes to information transfer. If we look at the body human

with today’s modern science of QED and electronic physics, a whole new science develops a world

different than the synthetic drug and surgery medicine we have today. Today’s so called modern

medicine is based on a 200 year old reductionism 17th century Newtonian antiquated physics. A true

new modern medicine of the body electric opens the door to a more affordable, sophisticated, safer,

and more efficient modern medicine. REF Body Electric

There is resistance to the flow of electricity. Louis Ampere discovered amperage, Volta

discovered Volts, and Dr. Ohm put a laws together to describe the relationship in terms of resistance.

resistance is in Ohms and Ohms law states that voltage equals amperage times resistance. This is the

first week of electronics class usually taught in 9th grade physics.

The right hand rule describes the fields around a flowing current. And it says that as a current

flows like your outstretched right thumb, a magnetic field is made at 90 degrees like your out

stretched fore finger, and a static field is made at 90 degrees like your outstretched middle finger.

Thus the fields of electricity are described. This is the second week of electronics class usually taught

in 10th grade physics. REF energetic medicine book

So all electrical action or flow of electricity generates a three dimensional field, at least. So we

called the process of measuring this field the trivector. This is a type of 3-dimensional voltammetry.

Voltammetry is the science of understanding how a substance’s electro-magnetic field reacts

with it’s environment. A hormone has electrons and protons and how they are placed in a 3

dimensional space will determine how it exchanges electron-magnetic action and this is measured by

measuring the 3 dimensional effect of it voltammetric field. The amount of charged particles is the

amperage, the pressure or potential of the charged particles is the volts. Basic 7th grade physics.

Every compound having it’s own individual and distinct voltammetric signature field. REF Votlammetry

Volts times amps is a power index or what is known as Watts. Once we measure simple

variables we can easily calculate a great variety of electrical forces. We can thus calculate volts, amps,

ohms, reactance, susceptance, watts, capacitance, inductance, impedance, and other virtual

mathematical calculations.

Knowing that reductionism has filed as a way to analyze the human body we can make more

global measures of these energies of a human, compare them to norms, and then using safe micro-

current stimulation change them.

We can detect and affect the body electric is safe and effective ways. The SCIO system is

designed and registered to do just this. To detect and affect, EEG, ECG, EMG, GSR, electro-osmosis,

trauma tissue, wounds, pain, charge stability, acid alkaline balance, voltammetric reactance of

substances, oxygenation, hydration, redox potentials, electro-acupuncture, bio-resonance, super-

learning, and other bio-electric functions. All from simple basic science taught in our schools today.

REF clinical evaluation

Only with the 40 years of experience to sharpen and perfect the precision of the art. The first

studies of Dr. Nelson on the body electric were done in Youngstown, Ohio. This ever dedicated

scientist has artfully perfected this art of energetic medicine. All designed as a truly modern medicine

to safely assay and treat the people.

The human body is a complicated intricate electrical assembly. It has a reactive set of fields

that are driven towards life giving things like oxygen food etc. It is electrically repelled from toxins.

This electrical field is processing the qualities of life such as metabolism and reproduction. Thus a vast

ever changing system of electrical fields, that are intricately interactive with the environment.

The human system is not a linear predictable or reduction type of system. It’s vast complicate

and elaborate functioning makes it a fractal complexity. As such it responds better to ever changing

fractal stimulation not linear reductionistic simple stimulation.

So developing an electrical treatment needed some advances in technology. First a cybernetic

loop of measuring, calculation, stimulation, measuring, calculation, stimulation, measuring,

calculation, stimulation, and so on. All at biological speeds. Then a reactive system that reacts to

fractal stimulation and an auto-focusing self adjusting stimulation. The body electric treats itself

beneath the human awareness of the limited word area of the brain. And thirdly a way to measure the

trivector field of items and then to measure the reactance of a person. All technological achievements

of Dr. Nelson and Dr. Nelson alone.

The body has a reactive trivector set of fields. An item not living has a stable unchanging

field. So to measure the substances fields, and then the person’s reaction to these fields. A truly

modern medicine is achieved, based on what we know of the body electric and basic high school

physics.

The Factors of Electro-potential What Are the Elements in the Human Body? Most of the human body is made up of water, H2O, with

cells consisting of 65-90% water by weight. Therefore, it isn't surprising that most of a human body's

mass is oxygen. Carbon, the basic unit for organic molecules, comes in second. 99% of the mass of

the human body is made up of just six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and

phosphorus. All other elements can be toxic or inert.

1. Oxygen (65%) the heavy component of water

2. Carbon (18%) the structure of all organic compounds and the key of fatty acids

3. Hydrogen (10%) water and free protons

4. Nitrogen (3%) air and amino acids

5. Calcium (1.5%) bone, nerve and all membranes

6. Phosphorus (1.0%) bone, nerve and all membranes

7. Potassium (0.35%) intracellular

8. Sulfur (0.25%) amino acids, good bacteria growth

9. Sodium (0.15%) extracellular

10. Magnesium (0.05%) regulatory for health

11. Copper, Zinc, Selenium, Molybdenum, Fluorine, Chlorine, Iodine, Manganese, Cobalt, Iron (0.70%)

12. Lithium, Strontium, Aluminum, Silicon, Lead, Vanadium, Arsenic, Bromine (trace amounts)

Life must keep Potassium inside the cell and Sodium outside of the cell. The natural thermodynamic

balance is for them to gravitate to be equal. So potassium has a natural pull to go out and sodium to go

into a cell. Because the concentration gradient for potassium is directed out of the cell, while the

concentration gradient for sodium is directed into the cell, there is a need for a sodium pump to stabilize

the life of the cell. This takes the energy of ATP to operate the sodium pump. The sodium-potassium

pump transports 2 potassium ions inside and 3 sodium ions outside at the cost of 1 ATP molecule. There

should be twice as much potassium as sodium in the healthy human body.

Membrane potentials are defined relative to the exterior of the cell; thus, a potential of −70 mV

implies that the interior of the cell is negative charge relative to the exterior. Life is electrical.

As we have said there should be twice as much potassium as sodium in the healthy human body.

But people like salt and producers put more salt into foods to sell and satisfy customers. Potassium

occurs mostly in fruit and vegetables. Potassium makes foods turn Orange. So oranges, pumpkin,

paprika, squash etc have the most. Most people get too much sodium and too little potassium. This puts

pressure on the potassium-sodium pump. This wastes ATP needed for other cellular functions and stress

the body electric. The excess sodium makes the body go acid with excess positive charge. This drives

the charge stability of the body to the acid state and is reflected in the measurements made from the

SCIO. There are many other factors that can upset this electrical balance.

The electro-potential of the cell membrane must be kept inside some strict limits to assure proper

electrical activity for life. The cell is an electrical dynamo needing energy for activity. This energy comes

from hot electrons (high quantum state energy of electrons in food). The food has gotten it’s energy from

the sun’s visible light photons energizing the electrons to higher quantum states. The quantum energy is

broken down in Krebs cycle to make ATP. Photons of heat are released. The cells will have electrical

activity that is of a tight range and thus electro-medicine will need to decipher the code of the types of

variations in the body electric that hallmark disease states. The cell must fight thermodynamics to live.

Correlations between whole-body impedance measurements and various bio-conductor volumes, such as total body water and fat-free mass, are experimentally well established; we can measure many different factors of the body electric. First there is skin electro-potential.

Each of these small little batteries we call cells blend in harmony to make the multi-cellular

organism we call the human. The hundred trillion cells in the human body act both in series and in parallel

to make the electro-potentials of the human body. Most of these cells are surrounded by fluid (interstitial,

lymph, blood etc.). Theses fluids are mostly water with lots of free protons, electrons and minerals which

further enhance the electrical factors. The normal cell has a resting voltage potential across the

membrane of 70milli-volts (-70mv). The brain cell will fire at peak voltage of +30mv so as to create a

difference of 100 milli-volts.

Thus the body has a measureable voltage and amperage while living. This electro-potential is

oscillating and or pulsing. Cells charge and discharge electricity at varying speeds. Global measures

reflect trends of the cells in the area to be measured. There are norms of these measures.

The amperage and voltage coming off of the body’s skin is of a range of zero to 5 milliamps and

1.5 volts. Zero is obvious as we all have seen the flat line in a movie telling us the person is dead. Normal

people put off micro-amperage and milli-volts, the extreme can be seen at over a volt. The criteria of

these potentials are derived from their location and oscillation.

The brain cell will fire with a process called action potential. An action potential is a very rapid change in membrane potential that occurs when a nerve cell membrane is stimulated. Specifically, the membrane potential goes from the resting potential (typically -70 mV) to some positive value (typically about +30 mV) in a very short period of time (just a few milliseconds).

What causes this change in potential to occur? The stimulus causes the sodium gates (or channels) to open and, because there's more sodium on the outside than the inside of the membrane, sodium then diffuses rapidly into the nerve cell. All these positively-charged sodium ions rushing in causes the membrane potential to become positive (the inside of the membrane is now positive relative to the outside). The sodium channels open only briefly, and then close again. This difference makes a potential at the skin measured by the SCIO system, as with all biofeedback systems.

The SCIO measures electro-potential at the 12 harness points in the clear, then applies a

voltammetric signal into any or all of the points, then measures the harness points with the applied signal.

The amperage and voltage coming off of the non stimulated body’s skin is of a range of zero to 5

milliamps and 1.5 volts. Zero is obvious as we all have seen the flat line in a movie telling us the person is

dead. Normal people put off micro-amperage and milli-volts, the extreme can be seen at over a volt. The

criteria of these potentials are derived from their location and oscillation.

If we measure on the scalp or the forehead as in the case of the SCIO, we can measure the transcutaneous correlate of the activity of brain cells firing in the brain below the point of measure. This is called EEG or electroencephalography. We can ascertain the Brain wave from the oscillation pattern. The pattern or rhythm of the brain wave is from 4 hertz as delta waves, 4-8 Hz for theta, 8 to 20 for alpha, and 20 to 100 for beta waves. If we measure the electro potential of the skin and filter out these waves we can get the EEG.

If we measure on the forehead, wrists and ankles as in the case of the SCIO, we can measure the transcutaneous correlate of the activity of muscle cell activity between the points of measure. This is called EMG or electromyleography. We can ascertain the muscle activity from the oscillation pattern. The pattern or rhythm of the muscle waves is from 250 to 1000 Hz. If we measure the electro potential of the skin and filter out these waves we can get the EMG.

If we measure on the wrists and left leg as in the case of the SCIO, we can measure the transcutaneous correlate of the activity of heart cells between the points of measure. This is called ECG or electrocardiography. We can ascertain the Heart wave from the oscillation pattern. The pattern or rhythm of the heart wave is from zero to 2 Hz. If we measure the electro potential of the skin and filter out these waves we can get the ECG. The heart signal is the largest in potential and smallest in time measured in biofeedback.

To measure skin resistance, we must apply a known voltammetric signal as an input and then see how much of it is resisted by the body, most applicably by the skin. The measure the galvanic skin resistance or impedance we need to be able to input a voltammetric signal into the electrode points. This is a variant signal in the SCIO of variant wave forms, and wave potentials. The measured output of resistance is usually non hertzian. Pulsations in resistance reactivity are fractal and non repeating.

The voltammetric signal of the SCIO is of a micro-current nature. The applied signal strength is derived from the base signal strength of the patient body natural. We are of the philosophy that signals exceeding twice the body norm will be considered invasive and the body will react adversely to such signals. We wish to just tickle the body with electro-stimulus near the natural. Thus the upper limits of the SCIO body stimulation output will be 5 volts, and 50 micro-amps. All of this is under the regulatory safety criteria specified.

Thus as seen in the EPFX FDA 1989 registration the SCIO is registered to measure volts and amps at 12 points of forehead, wrist and ankles. Input a voltammetric signal to these points, and then measure the reaction of resistance at these points. The SCIO then can acts as a frequency generator sending out voltammetric waveforms and a frequency counter measuring frequency response.

From these simple criteria a host of electrophysiological data can spin out to assist the SCIO in correcting aberrant electrophysiological functioning. Electro-stimulation is helpful in osmotic stimulation, transcutaneous electro-nerval-stimulation for pain control and injury or wound healing, redox stimulation, and others. The SCIO uses a cybernetic loop of analysis to use this electro stimulation to adjust electro-physiology of the patient.

Virtual or mathematical values can be calculated from the data. Reactivity is the change in amperage plus the change in voltage plus the change in resistance. Power is voltage times amperage. Capacitance is reflected by change in amperage. Inductance is reflected by change in voltage. Resonant frequency is a factor of ten to the 6

th times the square root of the inverse of capacitance times inductance.

Transcutaneous Voltammetric Evoked Potential (TVEP) is a measure of the reactivity to a know voltammetric signature signal. The voltammetric signal is measured by the QQC device and applied to the body and a reaction of the evoked reactive potential is then measured. The QQC technology is reviewed in the QQC literature from IMUNE.

Smooth muscle intracellular pH: measurement, regulation, and function

Smooth muscle performs many functions that are essential for the normal working of the human body.

Changes in pH are thought to affect many aspects of smooth muscle. Despite this, until recently little was

known about either intracellular pH (pHi) values or pHi regulation in smooth muscle.

Recent work

measuring pHi with either microelectrodes or nuclear magnetic resonance spectroscopy is now providing

some of this much needed information for smooth muscles. From these studies, it can be concluded

tentatively that pHi is the same in different smooth muscles, approximately 7.06 (37 degrees C). This

value is very close to those obtained in cardiac and skeletal muscle. It is clear that H+ is not in equilibrium

across the smooth muscle membrane; i.e., pHi is regulated. Preliminary results in

smooth muscle suggest

that certain aspects of this regulation are different from that described for other muscle types. Changes in

pHi have been found to produce marked effects on contraction in smooth muscle. Of particular

interest is

the fact that, unlike striated muscles, some smooth muscles can product more force during an intracellular

acidification.

Electric charge Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interactions. Electrically charged matter is influenced by, and produces, electromagnetic fields. The interaction between charge and field is the source of one of the four fundamental forces, the electromagnetic force.

Electric charge is a characteristic of almost every subatomic particle found in the universe. It is quantized: when expressed in units of the so-called elementary charge e, it takes integer or fractional values. Electrons by convention have a charge of −1, while protons have the opposite charge of +1. Quarks have a fractional charge of −

1⁄3 or +

2⁄3. The antiparticle equivalents of these (positrons, antiprotons, and

antiquarks, respectively) have the opposite charge. There are other charged particles. The discrete nature of electric charge was proposed by Michael Faraday in his electrolysis experiments, and then directly demonstrated by Robert Millikan in his oil-drop experiment.

In general, same-sign charged particles repel one another, while different-sign charged particles attract. This is expressed quantitatively in Coulomb's law, which states that the magnitude of the electrostatic repelling force between two particles is proportional to the product of their charges and the inverse square of the distance between them.

The electric charge of a macroscopic object is the sum of the electric charges of its constituent particles. Often, the net electric charge is zero, because it is favorable for the number of electrons in every atom to equal the number of protons (or, more generally, for the number of anions, or negatively charged atoms, in every molecule to equal the number of cations, or positively charged atoms). When the net electric charge is non-zero and motionless, one has the phenomenon known as static electricity. Even when the net charge is zero, it can be distributed non-uniformly (e.g., due to an external electric field, or due to molecular motion), in which case the material is said to be polarized. The charge due to the polarization is known as bound charge, while the excess charge brought from outside is called free charge. The motion of charged particles (e.g., of electrons in metals) in a particular direction is known as electric current.

Units

The SI unit of quantity of electric charge is the coulomb, which is equivalent to about 6.25 × 1018

e (e is the charge on a single electron or proton). Hence, the charge of an electron is approximately −1.602 x 10

−19 C. The coulomb is defined as the quantity of charge that has passed through the cross-section of an

electrical conductor carrying one ampere within one second. The symbol Q is often used to denote a quantity of electricity or charge. The quantity of electric charge can be directly measured with an electrometer, or indirectly measured with a ballistic galvanometer.

After finding the quantized character of charge, in 1891 Stoney proposed the unit 'electron' for this fundamental unit of electrical charge. This was before the discovery of the particle by J.J. Thomson in 1897. Today, the name "electron" for the unit of charge is no longer widely used except in the derived unit "electronvolt". This is quite surprising considering the wide use of this unit in the fields of physics and chemistry. The unit is today treated as nameless, referred to as "fundamental unit of charge" or simply as "e".

Formally, a measure of charge should be a multiple of the elementary charge e (charge is quantized), but since it is an average, macroscopic quantity, many orders of magnitude larger than a single elementary charge, it can effectively take on any real value. Furthermore, in some contexts it is meaningful to speak of fractions of a charge; e.g. in the charging of a capacitor.

History

Coulomb's torsion balance

As reported by the Ancient Greek philosopher Thales of Miletus around 600 BC, charge (or electricity) could be accumulated by rubbing fur on various substances, such as amber. The Greeks noted that the charged amber buttons could attract light objects such as hair. They also noted that if they rubbed the amber for long enough, they could even get a spark to jump. This property derives from the triboelectric effect.

In 1600 the English scientist William Gilbert returned to the subject in De Magnete, and coined the New Latin word electricus from ηλεκτρον (elektron), the Greek word for "amber", which soon gave rise to the English words "electric" and "electricity." He was followed in 1660 by Otto von Guericke, who invented what was probably the first electrostatic generator. Other European pioneers were Robert Boyle, who in 1675 stated that electric attraction and repulsion can act across a vacuum; Stephen Gray, who in 1729 classified materials as conductors and insulators; and C. F. du Fay, who proposed in 1733

[1] that

electricity came in two varieties which cancelled each other, and expressed this in terms of a two-fluid theory. When glass was rubbed with silk, du Fay said that the glass was charged with vitreous electricity, and when amber was rubbed with fur, the amber was said to be charged with resinous electricity. In 1839 Michael Faraday showed that the apparent division between static electricity, current electricity and bioelectricity was incorrect, and all were a consequence of the behavior of a single kind of electricity appearing in opposite polarities. It is arbitrary which polarity you call positive and which you call negative. Positive charge can be defined as the charge left on a glass rod after being rubbed with silk.

[2]

One of the foremost experts on electricity in the 18th century was Benjamin Franklin, who argued in favor of a one-fluid theory of electricity. Franklin imagined electricity as being a type of invisible fluid present in all matter; for example he believed that it was the glass in a Leyden jar that held the accumulated charge. He posited that rubbing insulating surfaces together caused this fluid to change location, and that a flow of this fluid constitutes an electric current. He also posited that when matter contained too little of the fluid it was "negatively" charged, and when it had an excess it was "positively" charged. Arbitrarily (or for a reason that was not recorded) he identified the term "positive" with vitreous electricity and "negative" with resinous electricity. William Watson arrived at the same explanation at about the same time.

Static electricity and electric current

Static electricity and electric current are two separate phenomena, both involving electric charge, and may occur simultaneously in the same object. Static electricity is a reference to the electric charge of an object and the related electrostatic discharge when two objects are brought together that are not at equilibrium. An electrostatic discharge creates a change in the charge of each of the two objects. In contrast, electric current is the flow of electric charge through an object, which produces no net loss or gain of electric charge. Although charge flows between two objects during an electrostatic discharge, time is too short for current to be maintained.

Properties

Flavour in particle physics

v • d • e

Flavour quantum numbers:

Baryon number: B

Lepton number: L

Strangeness: S

Charmness: C

Bottomness: B'

Topness: T

Isospin: I or Iz

Weak isospin: T or Tz

Electric charge: Q

Combinations:

Hypercharge: Y o Y = (B + S + C + B' + T) o Y = 2 (Q − Iz)

Weak hypercharge: YW o YW = 2 (Q − Tz) o X + 2YW = 5 (B − L)

Flavour mixing

CKM matrix

PMNS matrix

Flavour complementarity

Aside from the properties described in articles about electromagnetism, charge is a relativistic invariant. This means that any particle that has charge Q, no matter how fast it goes, always has charge Q. This property has been experimentally verified by showing that the charge of one helium nucleus (two protons and two neutrons bound together in a nucleus and moving around at high speeds) is the same as two deuterium nuclei (one proton and one neutron bound together, but moving much more slowly than they would if they were in a helium nucleus).

Conservation of electric charge

The total electric charge of an isolated system remains constant regardless of changes within the system itself. This law is inherent to all processes known to physics and can be derived in a local form from gauge invariance of the wave function. The conservation of charge results in the charge-current continuity equation. More generally, the net change in charge density ρ within a volume of integration V is equal to the area integral over the current density J on the surface of the area S, which is in turn equal to the net current I:

Thus, the conservation of electric charge, as expressed by the continuity equation, gives the result:

The charge transferred between times to and t is obtained by integrating both sides:

where I is the net outward current through a closed surface and Q is the electric charge contained within the volume defined by the surface.

Active transport across the membrane

Different types of transport across a cell membrane. Diffusion and osmosis are passive modes of transport, requiring no energy, moving from areas of high concentration to areas of low concentration. Active transport requires energy to transport molecules from

low concentration to high concentration.

Movement of molecules or ions across a cell membrane using energy provided by respiration. Examples of substances that can be actively transported across membranes are sodium ions and glucose.

Energy is needed because the movement occurs against a concentration gradient, with substances being moved from an area of low concentration to an area where there is a higher concentration. Active transport is therefore quite different from diffusion, which requires no input of energy. In diffusion the movement is in the opposite direction – from an area of high concentration to an area where the concentration is low. An example of diffusion is the movement of oxygen into the blood vessels of the lungs.

Passive Transport across the membrane

A molecule or ion that crosses the membrane by moving down a concentration or electrochemical gradient and without expenditure of metabolic energy is said to be transported passively. Another name for this process is diffusion. All molecules and ions are in constant motion and it is the energy of motion - kinetic energy - that drives passive transport. Transport of uncharged species across a membrane is dictated by differences in concentration of that species across the membrane - that is, by the prevailing concentration gradient. For ions and charged molecules, the electrical potential across the membrane also becomes critically important. Together, gradients in concentration and electric potential across the cell membrane constitute the electrochemical gradient that governs passive transport mechanisms.

Three distinctive types of passive transport are recognized in biological systems:

Transport by simple diffusion

Facilitated diffusion: carrier proteins and ion channels

Osmosis and hydrostatic pressure

Membrane potential (or transmembrane potential) is the voltage difference (or electrical potential difference) between the interior and exterior of a cell. Because the fluid inside and outside a cell is highly conductive, while a cell's plasma membrane is highly resistive, the voltage change in moving from a point outside to a point inside occurs largely within the narrow width of the membrane itself. Therefore, it is common to speak of the membrane potential as the voltage across the membrane.

The plasma membrane surrounds the cell to provide a stable environment for biological processes. The membrane potential arises from the action of ion channels, ion pumps, and ion transporters embedded in the membrane which maintain different ion concentrations inside and outside the cell. The term "membrane potential" is sometimes used interchangeably with cell potential but is applicable to any lipid bilayer or membrane.

Three special cases of physiological membrane potential with underlying mechanisms and the concept of equilibrium or reversal potential, which constitute the subject of electrophysiology and cellular biophysics, are addressed in this article. The former are resting membrane potential, action potential, and graded (postsynaptic) membrane potentials. The membrane potential of most not-excitable cells is kept at

relatively stable value of resting potential. In contrast, electrically excitable cells like neurons and myocytes can "fire" action potentials. Neurons are specialized to use changes in membrane potential for fast communication, with other neurons, muscles, and secretory cells. When cell membrane depolarizes from resting potential and produces action potential, it travels down the axon to the synapses: the magnitude of the axonal membrane potential varies dynamically along its length. On reaching a (chemical) synapse, a neurotransmitter is released causing a localized change in potential in the postsynaptic membrane of the target neuron by opening ion channels in its membrane. Importantly, every occasion of action potential firing results from spatial and temporal summation of often a very large number of minuscule graded postsynaptic responses of both positive (membrane depolarization) and negative (membrane hyperpolarization) polarities. Ultimately, such important aspects as value of resting potential, maximum amplitude and after-hyperpolarization phase of action potential can be easily understood utilizing the concept of equilibrium potential.

In the case of the resting membrane potential across an animal cell's plasma membrane, potassium (and sodium) gradients are established by the Na+/K+-ATPase (sodium-potassium pump) which transports 2 potassium ions inside and 3 sodium ions outside at the cost of 1 ATP molecule. In other cases, for example, a membrane potential may be established by acidification of the inside of a membranous compartment (such as the proton pump that generates membrane potential across synaptic vesicle membranes).

Contents

1 Reversal potential

2 Resting membrane potential

3 Action potential

4 Graded membrane potential

5 All other values of membrane potential

6 Effects and implications

7 See also

8 Notes

9 References

10 Further reading

11 External links

Reversal potential

An equilibrium or reversal potential of an ion is the value of transmembrane voltage at which the electric force generated by diffusional movement of the ion down its concentration gradient becomes equal to the molecular force of that diffusion. This means that the transmembrane voltage exactly matches (resists) the force of diffusion of the ion (or vice versa), such that the net current of the ion across the membrane is zero and unchanging. The equilibrium potential of a particular ion is designated by the notation Eion.The equilibrium potential for any ion can be calculated using the Nernst equation.

[1]

For example, reversal potential for potassium ions will be as follows:

The Nernst equation is frequently expressed in terms of base 10 logarithms (i.e., common logarithms) rather than natural logarithms, in which case it is written, for a cell at 25 °C:

The Nernst Equation and Resting Potential

At resting potential the sodium - potassium pumps move approximately the same electrical charge inside as outside the cell. However, potassium channels are also present allowing free flow of only potassium ions. The higher concentration of potassium inside the cell drives potassium ions to the outside. After a small number of potassium ions leave the cell the outside of the cell becomes positively charged compared to the inside, developing an electrical field. This electrical field balances the force on the ions from the concentration gradient and is known as the resting potential.

The Nernst equation for the potassium equilibrium potential over the cell membrane is

EK =

RT

ln

[K+]out

zF [K+]in

where

EK The electric potential across the membrane due to the potassium concentration gradient

R Universal gas constant (8.314472 J · K-1

)

T Absolute temperature (Kelvin = 273.15 + ºC = 298.15) at 25ºC

[K+]out potassium concentration outside membrane

[K+]in potassium concentration inside membrane

zF Number of electric charges carried by a mole of K+

z Number of electrons (one for K+)

F Faraday constant, equal to 9.6485309×104 C mol

-1

Putting values in the equation gives this result. Try changing the values in the text fields and clicking the update button to compute a new value for EK (values in formula will be updated).

EK = -86 mV

= 103 ×

8.314472 ·

298.15 ln

5 , where T = Kelvin, [K

+]out = mM, [K

+]in =

mM 1 · 96485.309 140

The 103 term converts from Volts to milliVolts. The computed number is a little higher than the quantity

measured in experiments (-70 mV) but all the factors in this complex physical process have been accounted for.

298.1 5

140

Apparently, even if two different ions have the same charge (ie. K+ and Na

+), they can still have very

different equilibrium potentials, provided their outside and/or inside concentrations differ. Take, for example, the equilibrium potentials of potassium and sodium in neurons. The potassium equilibrium potential EK is -84 mV with 5 mM potassium outside and 140 mM inside. The sodium equilibrium potential, on the other hand, ENa is approximately +40 mV with approximately 12 mM sodium inside and 140 mM outside.

Resting potential and action potential are often referred as "potassium" and "sodium" potentials, respectively. This stems from the origin of the resting potential (proximity to the EK), and the origin (activation of sodium channels) and the peak amplitude of the action potential (proximity to the ENa).

Resting membrane potential

A diagram showing the progression in the development of a membrane potential from a concentration

gradient (for potassium). Green arrows indicate net movement of K+ down a concentration gradient. Red

arrows indicate net movement of K+ due to the membrane potential. The diagram is misleading in that

while the concentration of potassium ions outside of the cell increases, only a small amount of K+ needs

to cross the membrane in order to produce a membrane potential with a magnitude large enough to

counter the tendency the potassium ions to move down the concentration gradient.

Relatively static membrane potential of quiescent cells is called resting membrane potential (or resting voltage), as opposed to the dynamic electrochemical phenomenona called action potential and graded membrane potential. Apart from the latter two, which occur in excitable cells (neurons, muscles, and some secretory cells in glands), membrane voltage in the non-excitable cells can also undergo changes in response to environmental or intracellular stimuli. For example, depolarization of the plasma membrane appears to be an important step in programmed cell death.

[2] In principle, there is no difference between

resting membrane potential and dynamic voltage changes like action potential from biophysical point of view: all these phenomena are caused by specific changes in membrane permeabilities for potassium, sodium, calcium, and chloride, which in turn result from concerted changes in functional activity of various ion channels, ion pumps, exchangers, and transporters. Conventionally, resting membrane potential can be defined as a relatively stable, ground, value of transmembrane voltage in animal and plant cells.

Generation of resting membrane potential is explicitly explained by Goldman equation.[3]

It is essentially the Nernst equation, in that it is based on the charges of the ions in question, as well as the difference between their inside and outside concentrations. However, it also takes into consideration the relative permeability of the plasma membrane to each ion in question.

For the three monovalent ions most important to action potentials: potassium (K

+), sodium (Na

+), and

chloride (Cl−). Being an anion, the chloride terms are treated differently than the cation terms; the inside

concentration is in the numerator, and the outside concentration is in the denominator, which is reversed from the cation terms. Pi stands for the permeability of the ion type i. If calcium ions are also considered, which are critically important for action potentials in muscles, the formula for the equilibrium potential becomes more complicated.

[4] The resting plasma membrane of the most animal cells is much more

permeable to K+, which results in the resting potential to be close to the potassium equilibrium

potential.[5][6]

The resting potential of a cell can be most thoroughly understood by thinking of it in terms of equilibrium potentials. In the example diagram here, the model cell was given only one permeant ion (potassium). In this case, the resting potential of this cell would be the same as the equilibrium potential for potassium.

However, a real cell is more complicated, having permeabilities to many ions, each of which contributes to the resting potential. To understand better, consider a cell with only two permeant ions, potassium and sodium. Consider a case where these two ions have equal concentration gradients directed in opposite directions, and that the membrane permeabilities to both ions are equal. K

+ leaving the cell will tend to

drag the membrane potential toward EK. Na+ entering the cell will tend to drag the membrane potential

toward the reversal potential for sodium ENa. Since the permeabilities to both ions were set to be equal, the membrane potential will, at the end of the Na

+/K

+ tug-of-war, end up halfway between ENa and EK. As

ENa and EK were equal but of opposite signs, halfway in between is zero, meaning that the membrane will rest at 0 mV.

Note that even though the membrane potential at 0 mV is stable, it is not an equilibrium condition because neither of the contributing ions are in equilibrium. Ions diffuse down their electrochemical gradients through ion channels, but the membrane potential is upheld by continual K

+ influx and Na

+ efflux

via ion pumps. Such situation with similar permeabilities for counter-acting ions, like potassium and sodium in animal cells, can be extremely costly for the cell if these permeabilities are relatively large, as it takes a lot of ATP energy to pump the ions back. Because no real cell can afford such equal and large ionic permeabilities at rest, resting potential of animal cells is determined by predominant high permeability to potassium and adjusted to the required value by modulating sodium and chloride permeabilities and gradients.

In a healthy animal cell Na+ permeability is about 5% of the K permeability or even less, whereas the

respective reversal potentials are +60 mV for sodium and -80 mV for potassium. Thus the membrane potential will not be right at EK, but rather depolarized from EK by an amount of approximately 5% of the 140 mV difference between EK and ENa. Thus, the cell's resting potential will be about −73 mV.

In a more formal notation, the membrane potential is the weighted average of each contributing ion's equilibrium potential (Goldman equation). The size of each weight is the relative permeability of each ion. In the normal case, where three ions contribute to the membrane potential:

The GHK voltage equation for positive ionic species and negative:

This results in the following if we consider a membrane separating two -solutions:

It is "Nernst-like" but has a term for each permeant ion. The Nernst equation can be considered a special case of the Goldman equation for only one ion:

= The membrane potential

= the permeability for that ion

= the extracellular concentration of that ion

= the intracellular concentration of that ion

= The ideal gas constant

= The temperature in kelvins

= Faraday's constant

The first term, before the parenthesis, can be reduced to 61.5 log for calculations at human body temperature (37 C)

Note that the ionic charge determines the sign of the membrane potential contribution.

The usefulness of the GHK equation to electrophysiologists is that it allows one to calculate the predicted membrane potential for any set of specified permeabilities. For example, if one wanted to calculate the resting potential of a cell, they would use the values of ion permeability that are present at rest (e.g. ). If one wanted to calculate the peak voltage of an action potential, one would simply substitute the permeabilities that are present at that time (e.g. ).

Em is the membrane potential, measured in volts

EX is the equilibrium potential for ion X, also in volts

PX is the relative permeability of ion X in arbitrary units (e.g. siemens for electrical conductance)

Ptot is the total permeability of all permeant ions, in this case Ptot = PK+ + PNa

+ + PCl

-

It is important to understand that ionic and water permeability of a pure lipid bilayer is very small, and it is similarly negligible for ions of comparable size, such as Na

+ and K

+. The cell membranes, however,

contain a large number of ion channels, water channels (aquaporins), and various ionic pumps, exchangers, and transporters, which can selectively increase permeability of the membrane for different ions. The relatively high membrane permeability for potassium ions at resting potential results from inward-rectifier potassium ion channels which are open at negative voltages, and so called leak potassium conductances such as two-barrel open rectifier K

+ channel (ORK

+) which is locked in the

open state irrespective of voltage. These potassium channels should not be confused with voltage-activated K

+ channels responsible for membrane repolarization during action potential.

Values of resting membrane potential in the most of the mature (differentiated) animal cells usually vary between EK and around -40 mV. Resting voltage in the excitable cells capable of producing action potentials is usually balanced around -60 mV because more depolarized voltage would lead to spontaneous activation of voltage-activated sodium channels and generate action potential. Immature or not-differentiated cells demonstrate highly variable values of resting voltage usually significantly more

positive than that in the differentiated cells.[7]

In such cells, the resting potential value correlates well with the degree of differentiation: undifferentiated cells can demonstrate resting potential value as low as 0 mV.

Maintenance of resting potential can be very costly for a cell, especially when the cell function requires a rather depolarized value of membrane voltage. For example, resting potential in day light-adapted blowfly (Calliphora vicina) photoreceptors can be as high as -30 mV.

[8]. In insect photoreceptors depolarization is

provided by light-activated TRP channels which cause fluctuations in membrane voltage in response to changing ambient light intensity. These changes in voltage then propagate as graded membrane responses to the synapses with a second-order neuron. At -30 mV, blowfly photoreceptor input resistance and membrane time constant can be as low as 10 MΩ and 1.5 ms, respectively, and the corner frequency of the voltage response power spectrum as high as 120 Hz. Such remarkably high corner frequency allows Calliphora vicina to produce the fastest functional responses ever recorded from an ocular photoreceptor.

[9] This excellent visual ability, however, is very expensive metabolically, because

such a low membrane resistance results from numerous open voltage-activated potassium and light-activated TRP channels, which, in turn, requires high level of Na+/K+-ATPase activity to maintain the proper ionic gradients. As a result, blowfly retina is one of the most, if not the most, energy demanding tissues in the fly both under dark- and light-adapted conditions.

[10][11][12] Maintenance of resting potential in

such cells may cost more than 20% of overall cellular ATP.[12]

On the other hand, high resting potential in the not-differentiated cells can be rather a great metabolic advantage, and not a burden for non-active cells such as stem cells. This apparent paradox is easily resolved by careful examination of the origin of that resting potential. Low-differentiated cells are characterized by extremely high input resistance

[7] which implies that leak and inward rectifier potassium

channels, which are responsible for high potassium permeability at rest, as well as other leak conductances (cloride and sodium, for example), are not expressed at this stage of cell life. As an apparent result, potassium permeability becomes similar to that for sodium ions, which places resting potential in-between the reversal potentials for sodium and potassium as discussed above. And because all ionic permeabilities in such cells are virtually the basic ionic leaks of a lipid bilayer, very little metabolic cost may be associated with maintenance of resting potential in such cells.

Action potential

Figure 1. A. view of an idealized action potential illustrates its various phases as the action potential

passes a point on a cell membrane. B. Actual recordings of action potentials are often distorted compared

to the schematic view because of variations in electrophysiological techniques used to make the

recording.

Figure 2. Train of action potentials is evoked by a depolarizing current stimulus. This is a whole-cell

current clamp recording (voltage is allowed to change freely while current amplitude is held constant)

Neurons communicate with other neurons, muscles, and organs via action potentials (APs), brief transient waveforms quickly "moving" along neuronal axons. The typical duration of an action potential registered with a pointed electrode is about 1 ms, which includes fast depolarization from the resting potential by means of opening of voltage-activated sodium channels, followed by slower repolarization of the membrane as a result of opening of voltage-activated potassium channels. After-hyperpolarization or "undershoot" is the final phase of an action potential which results from the activity of Na+/K+-ATPase (two K

+ ions in, three Na

+ ions out per cycle of pumping results in the net one positive charge leaving the

cell, i.e. one negative charge entering the cell), opening of calcium- and sodium-activated potassium channels, and deactivating delayed-rectifier potassium channels.

Action potential is initiated when membrane is depolarized above action potential activation threshold, which is approximately 20 mV above the resting potential level in neurons (-60 mV). In neurons in vivo, initial depolarization is caused by spatio-temporal summation of graded excitatory postsynaptic potentials (EPSPs), which is the "natural" mechanism of action potential initiation in neuronal networks. For example, it may require hundreds and thousands of EPSPs simultaneously or almost simultaneously converging on the neuron to evoke an action potential because a typical amplitude of an EPSP is 0.1 mV and the excitatory graded potentials are offset by their inhibitory counterparts, inhibitory postsynaptic potentials (IPSPs). Alternatively, action potentials can be initiated by external injection of a brief depolarizing current pulse in vitro and in vivo, during physiological experiments and in certain medical devices (see cardiac pacemaker). Sodium and potassium channels are key components of AP generation and propagation. Voltage-activated sodium channels, which are predominantly closed at resting voltage levels, react to a depolarizing perturbation by further opening, first gradually and linearly, but then, beyond a certain threshold, in a robust avalanche-like manner.

[13] The principal mechanism of AP

generation was discovered by Hodgkin & Huxsley [14]

and discussed in detail elsewhere (see Action Potential). Inactivation of sodium channels is responsible for the so called "absolute refractory period" after action potential. During that period of an order of few milliseconds duration no consequtive AP can be evoked by no matter how large depolarization. During the relative refractory period, a sufficient number of sodium channels (but not all) have recovered that an action potential can be provoked, but only with a stimulus much stronger than usual. These refractory periods ensure that the action potential travels in only one direction along the axon.

[15]

Action potentials usually originate at the axon hillock, where voltage-activated sodium channel density is the highest and their activation voltage threshold is the lowest, but they can be initiated in any part of neuron including dendrites and soma, if density of sodium channels allows it. Action potentials, originating from dendrites and soma have different shapes (broader in dendrites), and the critical amplitude of depolarizing perturbation (AP threshold level) changes as: dendrites > soma > axon hillock. APs usually propagate from axon hillock toward axonal synapses, but can also propagate back to soma and dendrites, although the biological significance and network calculation benefits of this phenomenon are not yet established.

[16]

Graded membrane potential

Figure 3. Graph displaying an EPSP, an IPSP, and the summation of an EPSP and an IPSP. When the

two are summed together the potential is still below the action potential threshold.

A graded membrane potential is a gradient of transmembrane potential difference along a length of cell membrane. Graded potentials are particularly important in neurons that lack action potentials, such as some types of retinal neurons. Graded potentials that depolarize the membrane, increasing the membrane potential above the resting potential, are important as "triggering potentials" that can spread along the surface of neuronal cell bodies to axon initial segments (the first part of the axon as it leaves the cell body) and trigger action potentials. Graded potentials that hyperpolarize the membrane potential to values more negative than the resting potential can inhibit the generation of action potentials. Graded potentials can arise at either portions of cells that function as sensory receptors or at synapses that are activated by neurotransmitters. These two types of graded potentials are called receptor potentials or synaptic potentials. Graded potentials are distinct from action potentials in that graded potentials spread electric potential changes along cell membranes without activating the kind of constant magnitude propagating signal that is characteristic of the action potential. Graded potentials are highest at a source and decay with increasing distance from the source.

All other values of membrane potential

From the viewpoint of biophysics, there is nothing particularly special about the resting membrane potential. It is merely the membrane potential that results from the membrane permeabilities that predominate when the cell is resting. The above equation of weighted averages always applies, but the following approach may be easier to visualize. At any given moment, there are two factors for an ion that determine how much influence that ion will have over the membrane potential of a cell.

1. That ion's driving force and, 2. That ion's permeability

Intuitively, this is easy to understand. If the driving force is high, then the ion is being "pushed" across the membrane hard (more correctly stated: it is diffusing in one direction faster than the other). If the permeability is high, it will be easier for the ion to diffuse across the membrane. But what are 'driving force' and 'permeability'?

Driving force: the driving force is the net electrical force available to move that ion across the membrane. It is calculated as the difference between the voltage that the ion "wants" to be at (its equilibrium potential) and the actual membrane potential (Em). So formally, the driving force for an ion = Em - Eion

For example, at our earlier calculated resting potential of −73 mV, the driving force on potassium is 7 mV ((−73 mV) − (−80 mV) = 7 mV. The driving force on sodium would be (−73 mV) − (60 mV) = −133 mV.

Permeability: is simply a measure of how easily an ion can cross the membrane. It is normally measured as the (electrical) conductance and the unit, siemens, corresponds to 1 C·s

-1·V

-1, that

is one charge per second per volt of potential.

So in a resting membrane, while the driving force for potassium is low, its permeability is very high. Sodium has a huge driving force, but almost no resting permeability. In this case, the math tells us that potassium carries about 20 times more current than sodium, and thus has 20 times more influence over Em than does sodium.

However, consider another case—the peak of the action potential. Here permeability to Na is high and K permeability is relatively low. Thus the membrane moves to near ENa and far from EK.

The more ions are permeant, the more complicated it becomes to predict the membrane potential. However, this can be done using the Goldman-Hodgkin-Katz equation or the weighted means equation. By simply plugging in the concentration gradients and the permeabilities of the ions at any instant in time, one can determine the membrane potential at that moment. What the GHK equations says, basically, is that at any time, the value of the membrane potential will be a weighted average of the equilibrium potentials of all permeant ions. The "weighting" is the ions relative permeability across the membrane.

Effects and implications

While cells expend energy to transport ions and establish a transmembrane potential, they use this potential in turn to transport other ions and metabolites such as sugar. The transmembrane potential of the mitochondria drives the production of ATP, which is the common currency of biological energy.

Cells may draw on the energy they store in the resting potential to drive action potentials or other forms of excitation. These changes in the membrane potential enable communication with other cells (as with action potentials) or initiate changes inside the cell, which happens in an egg when it is fertilized by a sperm.

In neuronal cells, an action potential begins with a rush of sodium ions into the cell through sodium channels, resulting in depolarization, while recovery involves an outward rush of potassium through potassium channels. Both these fluxes occur by passive diffusion.

See also

Action potential

Electrochemical potential

Goldman Equation

Membrane biophysics

Signal (biology)

Notes

1. ^ Note that the sign of ENa and EK are opposite. This is because the concentration gradient for potassium is directed out of the cell, while the concentration gradient for sodium is directed into the cell. Membrane potentials are defined relative to the exterior of the cell; thus, a potential of −70 mV implies that the interior of the cell is negative relative to the exterior.

Relatively static membrane potential of quiescent cells is called resting membrane potential (or resting voltage), as opposed to the specific dynamic electrochemical phenomenona called action potential and graded membrane potential.

Apart from the latter two, which occur in excitable cells (neurons, muscles, and some secretory cells in glands), membrane voltage in the majority of not-excitable cells can also undergo changes in response to environmental or intracellular stimuli

[citation needed]. In principle, there is no difference between resting

membrane potential and dynamic voltage changes like action potential from biophysical point of view: all these phenomena are caused by specific changes in membrane permeabilities for potassium, sodium, calcium, and chloride, which in turn result from concerted changes in functional activity of various ion channels, ion transporters, and exchangers. Conventionally, resting membrane potential can be defined as a relatively stable, ground, value of transmembrane voltage in animal and plant cells.

Any voltage is a difference in electric potential between two points - for example, the separation of positive and negative electric charges on opposite sides of a resistive barrier. The typical resting membrane potential of a cell arises from the separation of potassium ions from intracellular relatively immobile anion across the membrane of the cell. Because of the membrane permeability for potassium much higher than for other ions (consider any voltage-gated channels as not functional at this stage), and because of the strong chemical gradient for potassium, potassium ions flow from cytosole into the extracellular space carrying out positive charges, until their movement is not balanced by built-up of negative charges on the inner surface of the membrane. Again, because of the high relative permeability for potassium, the resulting membrane potential is almost always close to the potassium reversal potential. But in order for this process to occur, a concentration gradient of potassium ions must first be set up. This work is done by the ion pumps/transporters and/or exchangers and generally is powered by ATP.

In the case of the resting membrane potential across an animal cell's plasma membrane, potassium (and sodium) gradients are established by the Na+/K+-ATPase (sodium-potassium pump) which transports 2 potassium ions inside and 3 sodium ions outside at the cost of 1 ATP molecule. In other cases, for example, a membrane potential may be established by acidification of the inside of a membranous compartment (such as the proton pump that generates membrane potential across synaptic vesicle membranes).

[citation needed]

Contents

1 Electroneutrality

2 Generation of the resting potential

3 Membrane transport proteins

4 Equilibrium potentials

5 Resting potentials

6 Measuring resting potentials

7 Summary of resting potential values in different types of cells

8 References

9 See also

10 External links

Electroneutrality

In most quantitative treatments of membrane potential, such as the derivation of Goldman equation, electroneutrality is assumed; that is, that there is no measurable charge excess in any side of the

membrane. So, although there is an electric potential across the membrane due to charge separation, there is no actual measurable difference in the global concentration of positive and negative ions across the membrane (as it is estimated below), that is, there is no actual measurable charge excess in either side. That occurs because the effect of charge on electrochemical potential is hugely greater than the effect of concentration so an undetectable change in concentration creates a great change on electric potential.

Generation of the resting potential

Cell membranes are typically permeable to only a subset of ionic species. These species usually include potassium ions, chloride ions, bicarbonate ions, and others. To simplify the description of the ionic basis of the resting membrane potential, it is most useful to consider only one ionic species at first, and consider the others later. Since trans-plasma-membrane potentials are almost always determined primarily by potassium permeability, that is where to start.

A diagram showing the progression in the development of a membrane potential from a concentration

gradient (for potassium). Green arrows indicate net movement of K+ down a concentration gradient. Red

arrows indicate net movement of K+ due to the membrane potential. The diagram is misleading in that

while the concentration of potassium ions outside of the cell increases, only a small amount of K+ needs

to cross the membrane in order to produce a membrane potential with a magnitude large enough to

counter the tendency the potassium ions to move down the concentration gradient.

Panel 1 of the diagram shows a digramatic representation of a simple cell where a concentration gradient has already been established. This panel is drawn as if the membrane has no permeability to any ion. There is no membrane potential, because despite there being a concentration gradient for potassium, there is no net charge imbalance across the membrane. If the membrane were to become permeable to a type of ion that is more concentrated on one side of the membrane, then that ion would contribute to membrane voltage because the permeant ions would move across the membrane with net movement of that ion type down the concentration gradient. There would be net movement from the side of the membrane with a higher concentration of the ion to the side with lower concentration. Such a movement of one ion across the membrane would result in a net imbalance of charge across the membrane and a membrane potential. This is a common mechanism by which many cells establish a membrane potential.

In panel 2 of the diagram, the cell membrane has been made permeable to potassium ions, but not the anions (An

-) inside the cell. These anions are mostly contributed by protein. There is

energy stored in the potassium ion concentration gradient that can be converted into an electrical gradient when potassium (K) ions move out of the cell. Note that K ions can move across the membrane in both directions but by the purely statistical process that arises from the higher concentration of K inside the cell, there will be more K ions moving out of the cell. Because there is a higher concentration of K ions inside the cells, their random molecular motion is more likely to encounter the permeability pore (ion channel) than is the case for the K ions that are outside and at a lower concentration. An internal K

+ is simply "more likely" to leave the cell than an

extracellular K+ is to enter it. It is a matter of simple diffusion doing work by dissipating the

concentration gradient. As potassium leaves the cell, it is leaving behind the anions. Therefore a charge separation is developing as K

+ leaves the cell. This charge separation creates a

transmembrane voltage. This transmembrane voltage is the membrane potential. As potassium continues to leave the cell, separating more charges, the membrane potential will continue to grow. The length of the arrows (green indicating concentration gradient, red indicating voltage), represents the magnitude of potassium ion movement due to each form of energy. The direction of the arrow indicates the direction in which that particular force is applied. Thus, the building membrane voltage is an increasing force that acts counter to the tendency for net movement of K ions down the potassium concentration gradient.

In Panel 3, the membrane voltage has grown to the extent that its "strength" now matches the concentration gradient's. Since these forces (which are applied to K

+ ions) are now the same

strength and oriented in opposite directions, the system is now in equilibrium. Put another way, the tendency of potassium to leave the cell by running down its concentration gradient is now matched by the tendency of the membrane voltage to pull potassium ions back into the cell. K

+

continues to move across the membrane, but the rate at which it enters and leaves the cell are the same, thus, there is no net potassium current. Because the K

+ is at equilibrium, membrane

potential is stable, or "resting".

The resting voltage is the result of several ion-translocating enzymes (uniporters, cotransporters, and pumps) in the plasma membrane, steadily operating in parallel, whereby each ion-translocator has its characteristic electromotive force (= reversal potential = 'equilibrium voltage'), depending on the particular substrate concentrations inside and outside (internal ATP included in case of some pumps). H

+ exporting

ATPase render the membrane voltage in plants and fungi much more negative than in the more extensively investigated animal cells, where the resting voltage is mainly determined by selective ion channels.

In most neurons the resting potential has a value of approximately -70 mV. The resting potential is mostly determined by the concentrations of the ions in the fluids on both sides of the cell membrane and the ion transport proteins that are in the cell membrane. How the concentrations of ions and the membrane transport proteins influence the value of the resting potential is outlined below.

The resting potential of a cell can be most thoroughly understood by thinking of it in terms of equilibrium potentials. In the example diagram here, the model cell was given only one permeant ion (potassium). In this case, the resting potential of this cell would be the same as the equilibrium potential for potassium.

However, a real cell is more complicated, having permeabilities to many ions, each of which contributes to the resting potential. To understand better, consider a cell with only two permeant ions, potassium and sodium. Consider a case where these two ions have equal concentration gradients directed in opposite directions, and that the membrane permeabilities to both ions are equal. K

+ leaving the cell will tend to

drag the membrane potential toward EK. Na+ entering the cell will tend to drag the membrane potential

toward the reversal potential for sodium ENa. Since the permeabilities to both ions were set to be equal, the membrane potential will, at the end of the Na

+/K

+ tug-of-war, end up halfway between ENa and EK. As

ENa and EK were equal but of opposite signs, halfway in between is zero, meaning that the membrane will rest at 0 mV.

Note that even though the membrane potential at 0 mV is stable, it is not an equilibrium condition because neither of the contributing ions are in equilibrium. Ions diffuse down their electrochemical gradients through ion channels, but the membrane potential is upheld by continual K

+ influx and Na

+ efflux

via ion transporters. Such situation with similar permeabilities for counter-acting ions, like potassium and sodium in animal cells, can be extremely costly for the cell if these permeabilities are relatively large, as it takes a lot of ATP energy to pump the ions back. Because no real cell can afford such equal and large ionic permeabilities at rest, resting potential of animal cells is determined by predominant high permeability to potassium and adjusted to the required value by modulating sodium and chloride permeabilities and gradients.

In a healthy animal cell Na+ permeability is about 5% of the K permeability or even less, whereas the

respective reversal potentials are +60 mV for sodium (ENa)and -80 mV for potassium (EK). Thus the membrane potential will not be right at EK, but rather depolarized from EK by an amount of approximately 5% of the 140 mV difference between EK and ENa. Thus, the cell's resting potential will be about −73 mV.

In a more formal notation, the membrane potential is the weighted average of each contributing ion's equilibrium potential (Goldman equation). The size of each weight is the relative permeability of each ion. In the normal case, where three ions contribute to the membrane potential:

,

where

Em is the membrane potential, measured in volts

EX is the equilibrium potential for ion X, also in volts

PX is the relative permeability of ion X in arbitrary units (e.g. siemens for electrical conductance)

Ptot is the total permeability of all permeant ions, in this case PK+ + PNa

+ + PCl

-

Membrane transport proteins

For determination of membrane potentials, the two most important types of membrane ion transport proteins are ion channels and ion transporters. Ion channel proteins create paths across cell membranes through which ions can passively diffuse without direct expenditure of metabolic energy. They have selectivity for certain ions, thus, there are potassium-, chloride-, and sodium-selective ion channels. Different cells and even different parts of one cell (dendrites, cell bodies, nodes of Ranvier) will have different amounts of various ion transport proteins. Typically, the amount of certain potassium channels is most important for control of the resting potential (see below). Some ion pumps such as the Na+/K+-ATPase are electrogenic, that is, they produce charge imbalance across the cell membrane and can also contribute directly to the membrane potential. Most pumps use metabolic energy (ATP) to function.

Equilibrium potentials

For most animal cells potassium ions (K+) are the most important for the resting potential

[1]. Due to the

active transport of potassium ions, the concentration of potassium is higher inside cells than outside. Most cells have potassium-selective ion channel proteins that remain open all the time. There will be net movement of positively-charged potassium ions through these potassium channels with a resulting accumulation of excess negative charge inside of the cell. The outward movement of positively-charged potassium ions is due to random molecular motion (diffusion) and continues until enough excess negative charge accumulates inside the cell to form a membrane potential which can balance the difference in concentration of potassium between inside and outside the cell. "Balance" means that the electrical force (potential) that results from the build-up of ionic charge, and which impedes outward diffusion, increases until it is equal in magnitude but opposite in direction to the tendency for outward diffusive movement of potassium. This balance point is an equilibrium potential as the net transmembrane flux (or current) of K

+

is zero. The equilibrium potential for a given ion depends only upon the concentrations on either side of the membrane and the temperature. It can be calculated using the Nernst equation:

where

Eeq,K+ is the equilibrium potential for potassium, measured in volts

R is the universal gas constant, equal to 8.314 joules·K-1

·mol-1

T is the absolute temperature, measured in kelvins (= K = degrees Celsius + 273.15)

z is the number of elementary charges of the ion in question involved in the reaction

F is the Faraday constant, equal to 96,485 coulombs·mol-1

or J·V-1

·mol-1

[K+]o is the extracellular concentration of potassium, measured in mol·m

-3 or mmol·l

-1

[K+]i is likewise the intracellular concentration of potassium

Potassium equilibrium potentials of around -80 millivolts (inside negative) are common. Differences are observed in different species, different tissues within the same animal, and the same tissues under different environmental conditions. Applying the Nernst Equation above, one may account for these differences by changes in relative K

+ concentration or differences in temperature.

For common usage the Nernst equation is often given in a simplified form by assuming typical human body temperature (37 C), reducing the constants and switching to Log base 10. (The units used for concentration are unimportant as they will cancel out into a ratio). For Potassium at normal body temperature one may calculate the equilibrium potential in millivolts as:

Likewise the equilibrium potential for sodium (Na+) at normal human body temperature is calculated using

the same simplified constant. You can calculate E assuming the an outside concentration,[K+]o, of 100mM

and an inside concentration, [K+]i, of 10mM. For chloride ions (Cl

-) the sign of the constant must be

reversed (-61.54 mV). If calculating the equilibrium potential for calcium (Ca2+

) the 2+ charge halves the simplified constant to 30.77 mV. If working at room temperature, about 21 C, the calculated constants are approximately 58 mV for K

+ and Na

+, - 58 mV for Cl

- and 29 mV for Ca

2+. At physiological temperature,

about 29.5 C, and physiological concentrations (which vary for each ion), the calculated potentials are approximately 67 mV for Na

+, -90mV for K

+, -86 mV for Cl

- and 123 mV for Ca

2+.

Resting potentials

The resting membrane potential is not an equilibrium potential as it relies on the constant expenditure of energy (for ionic pumps as mentioned above) for its maintenance. It is a dynamic diffusion potential that takes mechanism into account—wholly unlike the equilibrium potential, which is true no matter the nature of the system under consideration. The resting membrane potential is dominated by the ionic species in the system that has the greatest conductance across the membrane. For most cells this is potassium. As potassium is also the ion with the most negative equilibrium potential, usually the resting potential can be no more negative than the potassium equilibrium potential. The resting potential can be calculated with the Goldman-Hodgkin-Katz voltage equation using the concentrations of ions as for the equilibrium potential while also including the relative permeabilities, or conductances, of each ionic species. Under normal conditions, it is safe to assume that only potassium, sodium (Na

+) and chloride (Cl

-) ions play large

roles for the resting potential:

This equation resembles the Nernst equation, but has a term for each permeant ion. Also, z has been inserted into the equation, causing the intracellular and extracellular concentrations of Cl

- to be reversed

relative to K+ and Na

+, as chloride's negative charge is handled by inverting the fraction inside the

logarithmic term. *Em is the membrane potential, measured in volts *R, T, and F are as above *PX is the relative permeability of ion X in arbitrary units (e.g. siemens for electrical conductance) *[X]Y is the concentration of ion X in compartment Y as above. Another way to view the membrane potential is using the Millman equation:

or reformulated

where Ptot is the combined permeability of all ionic species, again in arbitrary units. The latter equation portrays the resting membrane potential as a weighted average of the reversal potentials of the system, where the weights are the relative permeabilites across the membranes (PX/Ptot). During the action potential, these weights change. If the permeabilities of Na

+ and Cl

- are zero, the membrane potential

reduces to the Nernst potential for K+ (as PK

+ = Ptot). Normally, under resting conditions PNa+ and PCl- are

not zero, but they are much smaller than PK+, which renders Em close to Eeq,K+. Medical conditions such as hyperkalemia in which blood serum potassium (which governs [K

+]o) is changed are very dangerous

since they offset Eeq,K+, thus affecting Em. This may cause arrhythmias and cardiac arrest. The use of a bolus injection of potassium chloride in executions by lethal injection stops the heart by shifting the resting potential to a more positive value, which depolarizes and contracts the cardiac cells permanently, not allowing the heart to repolarize and thus enter diastole to be refilled with blood.

Measuring resting potentials

In some cells, the membrane potential is always changing (such as cardiac pacemaker cells). For such cells there is never any “rest” and the “resting potential” is a theoretical concept. Other cells with little in the way of membrane transport functions that change with time have a resting membrane potential that can be measured by inserting an electrode into the cell

[2]. Transmembrane potentials can also be

measured optically with dyes that change their optical properties according to the membrane potential.

Summary of resting potential values in different types of cells

The resting membrane potential in different cell types are approximately:

Skeletal muscle cells: −95 mV[3]

Smooth muscle cells: -50mV

References

1. ^ An example of an electrophysiological experiment to demonstrate the importance of K+ for the

resting potential. The dependence of the resting potential on the extracellular concentration of K+

is shown in Figure 2.6 of Neuroscience, 2nd edition, by Dale Purves, George J. Augustine, David Fitzpatrick, Lawrence C. Katz, Anthony-Samuel LaMantia, James O. McNamara, S. Mark Williams. Sunderland (MA): Sinauer Associates, Inc.; 2001.

2. ^ An illustrated example of measuring membrane potentials with electrodes is in Figure 2.1 of Neuroscience by Dale Purves, et al. (see reference #1, above).

3. ^ Kimball's Biology Pages - Muscles

The human nervous system consists of billions of nerve cells (or neurons)plus supporting (neuroglial) cells. Neurons are able to respond to stimuli (such as touch, sound, light, and so on), conduct impulses, and communicate with each other (and with other types of cells like muscle cells).

Nervous system

The nucleus of a neuron is located in the cell body. Extending out from the cell body are processes called dendrites and axons. These processes vary in number & relative length but always serve to conduct impulses (with dendrites conducting impulses toward the cell body and axons conducting impulses away from the cell body).

http://en.wikipedia.org/wiki/Image:Complete_neuron_cell_diagram_en.svg

Neurons can respond to stimuli and conduct impulses because a membrane potential is established across the cell membrane. In other words, there is an unequal distribution of ions (charged atoms) on the two sides of a nerve cell membrane. This can be illustrated with a voltmeter:

With one electrode placed inside a neuron and the other outside, the voltmeter is 'measuring' the difference in the distribution of ions on the inside versus the outside. And, in this example, the voltmeter reads -70 mV (mV = millivolts). In other words, the inside of the neuron is slightly negative relative to the outside. This difference is referred to as the Resting Membrane Potential. How is this potential established?

The membranes of all nerve cells have a potential difference across them, with the cell interior negative with respect to the exterior (a). In neurons, stimuli can alter this potential difference by opening sodium channels in the membrane. For example, neurotransmitters interact specifically with sodium channels (or gates). So sodium ions flow into the cell, reducing the voltage across the membrane.

Once the potential difference reaches a threshold voltage, the reduced voltage causes hundreds of sodium gates in that region of the membrane to open briefly. Sodium ions flood into the cell, completely depolarizing the membrane (b). This opens more voltage-gated ion channels in the adjacent membrane, and so a wave of depolarization courses along the cell — the action potential.

As the action potential nears its peak, the sodium gates close, and potassium gates open, allowing ions to flow out of the cell to restore the normal potential of the membrane (c) (Gutkin and Ermentrout 2006).

Establishment of the Resting Membrane Potential

Membranes are polarized or, in other words, exhibit a RESTING MEMBRANE POTENTIAL. This means that there is an unequal distribution of ions (atoms with a positive or negative charge) on the two sides of the nerve cell membrane. This POTENTIAL generally measures about 70 millivolts (with the INSIDE of the membrane negative with respect to the outside). So, the RESTING MEMBRANE POTENTIAL is expressed as -70 mV, and the minus means that the inside is negative relative to (or compared to) the outside. It is called a RESTING potential because it occurs when a membrane is not being stimulated or conducting impulses (in other words, it's resting).

Source: http://www.millersv.edu/~bio375/CELL/membrane/membrane.htm

What factors contribute to this membrane potential?

Two ions are responsible: sodium (Na+) and potassium (K+). An unequal distribution of these two ions occurs on the two sides of a nerve cell membrane because carriers actively transport these two ions: sodium from the inside to the outside and potassium from the outside to the inside. AS A RESULT of this active transport mechanism (commonly referred to as the SODIUM - POTASSIUM PUMP), there is a higher concentration of sodium on the outside than the inside and a higher concentration of potassium on the inside than the outside.

The Sodium-Potassium Pump

Used with permission of Gary Kaiser

Source: http://ifcsun1.ifisiol.unam.mx/Brain/mempot.htm

Sodium-potassium pump

The nerve cell membrane also contains special passageways for these two ions that are commonly referred to as GATES or CHANNELS. Thus, there are SODIUM GATES and POTASSIUM GATES. These gates represent the only way that these ions can diffuse through a nerve cell membrane. IN A RESTING NERVE CELL MEMBRANE, all the sodium gates are closed and some of the potassium gates are open. AS A RESULT, sodium cannot diffuse through the membrane & largely remains outside the membrane. HOWEVER, some potassium ions are able to diffuse out.

OVERALL, therefore, there are lots of positively charged potassium ions just inside the membrane and lots of positively charged sodium ions PLUS some potassium ions on the outside. THIS MEANS THAT THERE ARE MORE POSITIVE CHARGES ON THE OUTSIDE THAN ON THE INSIDE. In other words, there is an unequal distribution of ions or a resting membrane potential. This potential will be maintained until the membrane is disturbed or stimulated. Then, if it's a sufficiently strong stimulus, an action potential will occur.

Membrane potential

Voltage sensing in a potassium ion channel. a, The control of ion flow through voltage-gated channels is very sensitive to the voltage

across the cell membrane. By comparison, an electronic device such as a transistor is much less sensitive to applied voltage.

b, MacKinnon and colleagues (Zhou et al. 2001) have found that the voltage sensors in a bacterial potassium channel are charged 'paddles'

that move through the fluid membrane interior. Four voltage sensors (two of which are shown here) are linked mechanically to

the channel's 'gate'. Each voltage sensor has four tethered positive charges (amino acids); the high sensitivity of

channel gating results from the transport of so many charges, 16 in all, most of the way across the membrane (From: Sigworth 2003).

In a cross section view of the voltage-dependent potassium channel, two of the four paddles move up and down, opening and closing the

central pore through which potassium ions flow out of the cell, restoring the cell's normal negative inside, positive outside polarity.

ACTION POTENTIAL

An action potential is a very rapid change in membrane potential that occurs when a nerve cell membrane is stimulated. Specifically, the membrane potential goes from the resting potential (typically -70 mV) to some positive value (typically about +30 mV) in a very short period of time (just a few milliseconds).

Source: http://faculty.washington.edu/chudler/ap.html

What causes this change in potential to occur? The stimulus causes the sodium gates (or channels) to open and, because there's more sodium on the outside than the inside of the membrane, sodium then diffuses rapidly into the nerve cell. All these positively-charged sodiums rushing in causes the membrane potential to become positive (the inside of the membrane is now positive relative to the outside). The sodium channels open only briefly, then close again.

The potassium channels then open, and, because there is more potassium inside the membrane than outside, positively-charged potassium ions diffuse out. As these positive ions go out, the inside of the membrane once again becomes negative with respect to the outside (Animation: Voltage-gated channels) .

Source: http://faculty.washington.edu/chudler/ap.html

Threshold stimulus & potential

Action potentials occur only when the membrane in stimulated (depolarized) enough so that sodium channels open completely. The minimum stimulus needed to achieve an action potential is called the threshold stimulus.

The threshold stimulus causes the membrane potential to become less negative (because a stimulus, no matter how small, causes a few sodium channels to open and allows some positively-charged sodium ions to diffuse in).

If the membrane potential reaches the threshold potential (generally 5 - 15 mV less negative than the resting potential), the voltage-regulated sodium channels all open. Sodium ions rapidly diffuse inward, & depolarization occurs.

All-or-None Law - action potentials occur maximally or not at all. In other words, there's no such thing as a partial or weak action potential. Either the threshold potential is reached and an action potential occurs,

or it isn't reached and no action potential occurs.

Refractory periods:

ABSOLUTE -

o During an action potential, a second stimulus will not produce a second action potential (no matter how strong that stimulus is)

o corresponds to the period when the sodium channels are open (typically just a millisecond or less)

Source: http://members.aol.com/Bio50/LecNotes/lecnot11.html

RELATIVE -

o Another action potential can be produced, but only if the stimulus is greater than the threshold stimulus

o corresponds to the period when the potassium channels are open (several milliseconds) o the nerve cell membrane becomes progressively more 'sensitive' (easier to stimulate) as

the relative refractory period proceeds. So, it takes a very strong stimulus to cause an action potential at the beginning of the relative refractory period, but only a slightly above threshold stimulus to cause an action potential near the end of the relative refractory period

The absolute refractory period places a limit on the rate at which a neuron can conduct impulses, and the relative refractory period permits variation in the rate at which a neuron conducts impulses. Such variation is important because it is one of the ways by which our nervous system recognizes differences in stimulus strength, e.g., dim light = retinal cells conduct fewer impulses per second vs. brighter light = retinal cells conduct more impulses per second.

How does the relative refractory period permit variation in rate of impulse conduction? Let's assume that the relative refractory period of a neuron is 20 milliseconds long and, further, that the threshold stimulus for that neuron (as determined, for example, in a lab experiment with that neuron) is 0.5 volt. If that neuron is continuously stimulated at a level of 0.5 volt, then an action potential (and impulse) will be generated every 20 milliseconds (because once an action potential has been generated with a threshold stimulus [and ignoring the absolute refractory period], another action potential cannot occur until the relative refractory period is over). So, in this example, the rate of stimulation (and impulse conduction) would be 50 per second (1 sec = 1000 ms; 1000 ms divided by 20 ms = 50).

If we increase the stimulus (e.g., from 0.5 volt to 1 volt), what happens to the rate at which action potentials (and impulses) occur? Because 1 volt is an above-threshold stimulus, it means that, once an actional potential has been generated, another one will occur in less than 20 ms or, in other words, before the end of the relative refractory period. Thus, in our example, the increased stimulus will increase the rate of impulse conduction above 50 per second. Without more information, it's not possible to calculate the exact rate. However, it's sufficient that you understand that increasing stimulus strength will result in an increase in the rate of impulse conduction.

Impulse conduction - an impulse is simply the movement of action potentials along a nerve cell. Action potentials are localized (only affect a small area of nerve cell membrane). So, when one occurs, only a small area of membrane depolarizes (or 'reverses' potential). As a result, for a split second, areas of membrane adjacent to each other have opposite charges (the depolarized membrane is negative on the outside & positive on the inside, while the adjacent areas are still positive on the outside and negative on the inside). An electrical circuit (or 'mini-circuit') develops between these oppositely-charged areas (or, in other words, electrons flow between these areas). This 'mini-circuit' stimulates the adjacent area and, therefore, an action potential occurs. This process repeats itself and action potentials move down the nerve cell membrane. This 'movement' of action potentials is called an impulse.

Conduction Velocity:

impulses typically travel along neurons at a speed of anywhere from 1 to 120 meters per second

the speed of conduction can be influenced by: o the diameter of a fiber o the presence or absence of myelin

Neurons with myelin (or myelinated neurons) conduct impulses much faster than those without myelin.

The myelin sheath (blue) surrounding axons (yellow) is produced by glial cells (Schwann cells in the PNS,

oligodendrocytes in the CNS). These cells produce large membranous extensions that ensheath the axons in successive layers that are then compacted by exclusion of cytoplasm (black) to form the myelin sheath. The thickness of the myelin

sheath (the number of wraps around the axon) is proportional to the axon's diameter.

Myelination, the process by which glial cells ensheath the axons of neurons in layers of myelin, ensures the rapid conduction of electrical impulses in the nervous system. The formation of myelin sheaths is one of the most spectacular examples of cell-cell interaction and coordination in nature. Myelin sheaths are formed by the vast membranous extensions of glial cells: Schwann cells in the peripheral nervous system (PNS) and oligodendrocytes in the central nervous system (CNS). The axon is wrapped many times (like a Swiss roll) by these sheetlike membrane extensions to form the final myelin sheath, or internode. Internodes can be as long as 1 mm and are separated from their neighbors by a short gap (the node of Ranvier) of 1 micrometer. The concentration of voltage-dependent sodium channels in the axon membrane at the node, and the high electrical resistance of the multilayered myelin sheath, ensure that action potentials jump from node to node (a process termed "saltatory conduction") (ffrench-Constant 2004).

Schwann cells (or oligodendrocytes) are located at regular intervals along the process (axons and, for some neurons, dendrites) & so a section of a myelinated axon would look like this:

Between areas of myelin are non-myelinated areas called the nodes of Ranvier. Because fat (myelin) acts as an insulator, membrane coated with myelin will not conduct an impulse. So, in a myelinated neuron, action potentials only occur along the nodes and, therefore, impulses 'jump' over the areas of myelin - going from node to node in a process called saltatory conduction (with the word saltatory meaning 'jumping'):

Because the impulse 'jumps' over areas of myelin, an impulse travels much faster along a myelinated neuron than along a non-myelinated neuron.

Types of Neurons - the three main types of neurons are:

Multipolar

neuron

Unipolar

neuron

Bipolar neuron

Multipolar neurons are so-named because they have many (multi-) processes that extend from the cell body: lots of dendrites plus a single axon. Functionally, these neurons are either motor (conducting impulses that will cause activity such as the contraction of muscles) or association (conducting impulses and permitting 'communication' between neurons within the central nervous system).

Unipolar neurons have but one process from the cell body. However, that single, very short, process splits into longer processes (a dendrite plus an axon). Unipolar neurons are sensory neurons - conducting impulses into the central nervous system.

Bipolar neurons have two processes - one axon & one dendrite. These neurons are also sensory. For example, biopolar neurons can be found in the retina of the eye.

Neuroglial, or glial, cells - general functions include:

1 - forming myelin sheaths 2 - protecting neurons (via phagocytosis) 3 - regulating the internal environment of neurons in the central nervous system

Synapse = point of impulse transmission between neurons; impulses are transmitted from pre-synaptic

neurons to post-synaptic neurons

Synapses usually occur between the axon of a pre-synaptic neuron & a dendrite or cell body of a post-synaptic neuron. At a synapse, the end of the axon is 'swollen' and referred to as an end bulb or synaptic knob. Within the end bulb are found lots of synaptic vesicles (which contain neurotransmitter chemicals) and mitochondria (which provide ATP to make more neurotransmitter). Between the end bulb and the dendrite (or cell body) of the post-synaptic neuron, there is a gap commonly referred to as the synaptic cleft. So, pre- and post-synaptic membranes do not actually come in contact. That means that the

impulse cannot be transmitted directly. Rather, the impulse is transmitted by the release of chemicals called chemical transmitters (or neurotransmitters).

http://www.nia.nih.gov/NR/rdonlyres/4E12F6CF-2436-47DB-8CC5-

607E82B2B8E4/2372/neurons_big1.jpg

Micrograph of a synapse (Schikorski and Stevens 2001).

Structural features of a typical nerve cell (i.e., neuron) and synapse. This drawing shows the major components of a typical neuron,

including the cell body with the nucleus; the dendrites that receive signals from other neurons; and the axon that relays nerve signals to other neurons at a specialized structure called a synapse. When the nerve signal reaches the synapse, it causes the release of chemical messengers (i.e., neurotransmitters) from storage vesicles. The neurotransmitters travel across a minute gap between the cells and then

interact with protein molecules (i.e., receptors) located in the membrane surrounding the signal-receiving neuron. This interaction causes biochemical reactions that result in the generation, or prevention, of a new nerve signal, depending on the type of neuron, neurotransmitter,

and receptor involved (Goodlett and Horn 2001).

Synapse

When an impulse arrives at the end bulb, the end bulb membrane becomes more permeable to calcium. Calcium diffuses into the end bulb & activates enzymes that cause the synaptic vesicles to move toward

the synaptic cleft. Some vesicles fuse with the membrane and release their neurotransmitter (a good example of exocytosis). The neurotransmitter molecules diffuse across the cleft and fit into receptor sites

in the postsynaptic membrane. When these sites are filled, sodium channels open & permit an inward diffusion of sodium ions. This, of course, causes the membrane potential to become less negative (or, in

other words, to approach the threshold potential). If enough neurotransmitter is released, and enough sodium channels are opened, then the membrane potential will reach threshold. If so, an action potential occurs and spreads along the membrane of the post-synaptic neuron (in other words, the impulse will be

transmitted). Of course, if insufficient neurotransmitter is released, the impulse will not be transmitted.

Impulse transmission - The nerve impulse (action potential) travels down the presynaptic axon towards the synapse, where it activates voltage-gated calcium channels leading to calcium influx, which triggers

the simultaneous release of neurotransmitter molecules from many synaptic vesicles by fusing the membranes of the vesicles to that of the nerve terminal. The neurotransmitter molecules diffuse across

the synaptic cleft, bind briefly to receptors on the postsynaptic neuron to activate them, causing physiological responses that may be excitatory or inhibitory depending on the receptor. The

neurotransmitter molecules are then either quickly pumped back into the presynaptic nerve terminal via transporters, are destroyed by enzymes near the receptors (e.g. breakdown of acetylcholine by

cholinesterase), or diffuse into the surrounding area.

This describes what happens when an 'excitatory' neurotransmitter is released at a synapse. However, not all neurotransmitters are 'excitatory.'

Types of neurotransmitters:

1- Excitatory - neurotransmitters that make membrane potential less negative (via increased

permeability of the membrane to sodium) &, therefore, tend to 'excite' or stimulate the

postsynaptic membrane

2 - Inhibitory - neurotransmitters that make membrane potential more negative (via increased permeability of the membrane to potassium) &, therefore, tend to 'inhibit' (or make less likely) the transmission of an impulse. One example of an inhibitory neurotransmitter is gamma aminobutyric acid (GABA; shown below). Medically, GABA has been used to treat both epilepsy

and hypertension. Another example of an inhibitory neurotransmitter is beta-endorphin, which results in decreased pain perception by the CNS.

Used by permission of John W. Kimball

Summation:

1 - Temporal summation - transmission of an impulse by rapid stimulation of one or more pre-

synaptic neurons

2 - Spatial summation - transmission of an impulse by simultaneous or nearly simultaneous stimulation of two or more pre-synaptic neurons

Used by permission of John W. Kimball

Literature cited

ffrench-Constant, C., H. Colognato, and R. J. M. Franklin. 2004. Neuroscience: the mysteries of myelin unwrapped. Science 304:688-689.

Goodlett, C.R., and K. H. Horn. 2001. Mechanisms of alcohol-induced damage to the developing nervous system. Alcohol Research & Health 25:175–184.

Gutkin, B. and G. B. Ermentrout. 2006. Neuroscience: spikes too kinky in the cortex? Nature 440: 999-1000.

Schikorski, T. and C. F. Stevens. 2001. Morphological correlates of functionally defined synaptic vesicle populations. Nature Neuroscience 4: 391-395.

Sigworth, F. J. 2003. Structural biology: life's transistors. Nature 423:21-22.

Zhou, M., João H. Morais-Cabral, Sabine Mann and Roderick MacKinnon. 2001. Potassium channel receptor site for the inactivation gate and quaternary amine inhibitors. Nature 411:657-661.

References

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3. ^ Purves et al., pp. 32–33; Bullock, Orkand, and Grinnell, pp. 138–140; Schmidt-Nielsen, pp. 480; Junge, pp. 35–37

4. ^ Spangler SG (1972). "Expansion of the constant field equation to include both divalent and monovalent ions". Ala J Med Sci 9: 218–23. PMID 5045041.

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a b Magnuson DS, Morassutti DJ, Staines WA, McBurney MW, Marshall KC. (1995 Jan 14). "In

vivo electrophysiological maturation of neurons derived from a multipotent precursor (embryonal carcinoma) cell line". Brain Res Dev Brain Res. 84 (1): 130-41.

8. ^ Juusola M, Kouvalainen E, Järvilehto M, Weckström M. (1994 Sep). "Contrast gain, signal-to-noise ratio, and linearity in light-adapted blowfly photoreceptors". J Gen Physiol. 104 (3): 593-621. PMID 7807062.

9. ^ Tatler B, O'Carroll DC, Laughlin SB. (2000 Apr). "Temperature and the temporal resolving power of fly photoreceptors". J Comp Physiol [A]. 186 (4): 399-407. PMID 10798727.

10. ^ Weckström M, Hardie RC, Laughlin SB. (1991). "Voltage-activated potassium channels in blowfly photoreceptors and their role in light adaptation". J Physiol. 440: 635-57. PMID 1804980.

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of neural information". Nat Neurosci. 1 (1): 36-41. PMID 10195106.

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Further reading

Alberts et al. Molecular Biology of the Cell. Garland Publishing; 4th Bk&Cdr edition (March, 2002). ISBN 0-8153-3218-1. Undergraduate level.

Guyton, Arthur C., John E. Hall. Textbook of medical physiology. W.B. Saunders Company; 10th edition (August 15, 2000). ISBN 0-7216-8677-X. Undergraduate level.

Hille, B. Ionic Channel of Excitable Membranes Sinauer Associates, Sunderland, MA, USA; 1st Edition, 1984. ISBN 0-87893-322-0

Nicholls, J.G., Martin, A.R. and Wallace, B.G. From Neuron to Brain Sinauer Associates, Inc. Sunderland, MA, USA 3rd Edition, 1992. ISBN 0-87893-580-0

Ove-Sten Knudsen. Biological Membranes: Theory of Transport, Potentials and Electric Impulses. Cambridge University Press (September 26, 2002). ISBN 0-521-81018-3. Graduate level.

National Medical Series for Independent Study. Physiology. Lippincott Williams & Wilkins. Philadelphia, PE, USA 4th Edition, 2001. ISBN 0-638-30603-0

J Psychosom Res. 1985;29(3):247-57. Links

Long-term high frequency transcutaneous electrical nerve stimulation (hi-TNS) in chronic pain.

Clinical response and effects on CSF-endorphins, monoamine metabolites, substance P-like

immunoreactivity (SPLI) and pain measures.

Almay BG, Johansson F, von Knorring L, Sakurada T, Terenius L.

Eighteen patients with chronic pain syndromes of organic origin were treated by means of

high frequency transcutaneous nerve stimulation (hi-TNS). The CSF levels of

receptorassayable Fraction I and II endorphins, substance P-like immunoreactivity (SPLI),

and the monoamine metabolites 5-HIAA, HVA and MOPEG were measured before and after

one week of daily treatment. Furthermore, the effects on experimental pain measures were

determined. The therapeutic effect was evaluated after 30 days and 3 months of treatment.

Patients with low initial concentrations of endorphins in CSF, lower than those observed in

healthy volunteers, tended to have the best response to hi-TNS. There were significant

increases in Fraction I endorphins and SPLI in CSF, most pronounced in the patients who

responded. There were no significant changes in 5-HIAA, HVA or MOPEG in CSF. However, in

early responders, the serotonin metabolite 5-HIAA tended to decrease as contrasted to an

increase in non-responders. The difference between the groups was statistically significant.

Confirming our earlier studies, the therapy induced changes in pain measures showed a

significant, positive correlation with increasing Fraction I endorphins in CSF. Our results

suggest that hi-TNS induces central changes in the endorphinergic, serotonergic and possibly

substance-P-ergic systems

Caroline S. Pace1 and John T. Tarvin

1, 2

(1) Department of Physiology and Biophysics and Diabetes Research and Training Hospital, University of Alabama in Birmingham, 35294 Birmingham, Alabama

(2) Present address: Department of Physics, University of Mississippi, 38677 Oxford, Miss.

Received: 4 June 1982 Revised: 23 September 1982

Summary Regulation of intracellular pH is an essential function and may be especially significant in the B-cell in which the influence of glucose on electrical activity is modulated by alterations in pH. Two possible regulatory processes have been examined: Na/H and HCO3/Cl exchange, by using inhibitors, an ionophore, and changes of ionic concentrations. In the presence of 11.1MM glucose we found that DIDS, an inhibitor of anion exchange, elicited a dose-response increase in the relative duration of the active

phase with an ED50 of 99 M. Probenecid (0.5MM), an inhibitor of anion fluxes, also augmented the electrical activity (EA) due to glucose. Withdrawal of HCO 3

– elicited constant spike activity followed by a

resumption of burst activity with a greater duration of the active phase compared to control. These data are consistent with predicted cellular acidification. However, reduction of Cl o

– by isethionate substitution

produced no marked effect on EA. In contrast, Cl o – substitution for Cl

– resulted in variable effects

characterized by constant spike activity or a decrease in the duration of the active and silent phases

along with silent hyperpolarization. Tributyltin, a Cl/OH, ionophore enhanced EA at 0.25 M with 120MM Cl o

– , but reduced EA with 10MM Cl

– as would be predicted with either cellular acidification or

alkalinization, respectively. Amiloride at 100 M elicited constant spike activity perhaps due to inhibition of Na/H exchange. Reduction of Na o

+ from 142.8 to 40.8MM had a similar effect and enhanced the

influence of amiloride. It appears therefore that interference with putative pH regulatory mechanisms in the B-cell are consistent with the hypothesis that cell pH is involved in regulation of EA.

Key Words DIDS - probenecid - amiloride - isethionate - tributyltin - mouse islet

Annual Review of Neuroscience Vol. 7: 257-278 (Volume publication date March 1984) (doi:10.1146/annurev.ne.07.030184.001353) Effects of Intracellular H+ on the Electrical Properties of Excitable Cells W Moody, Jr

Circulation. 1950;2:811.)

© 1950 American Heart Association, Inc.

Electrical Impedance Plethysmography

A Physical and Physiologic Approach to Peripheral Vascular Study

JAN NYBOER SC.D., M.D.1; Marian M. Kreider M.D.

1; Leonard Hannapel M.D.

1

1 From the Department of Physiological Sciences, Dartmouth Medical School, Hanover, New Hampshire

and Veterans Administration Hospital, White River Junction, Vermont.

The quantity of blood measured by electrical impedance plethysmography is defined by its resistive effect

in parallel to the resistance of other tissue of the segment. By substitution of this parallel

resistive value,

together with data relative to the resistivity of blood and the length of the segment in the formula for the

volume of an electrical conductor, we are able to derive the volume of the pulse in cubic centimeters. It

follows that the volume displaced from the venous reservoir and the rate of refilling

of the venous reservoir

of an extremity may also be determined quantitatively.

Brain electrical correlates of psychological measures: Strategies and problems

Journal Brain Topography

Publisher Springer New York

ISSN 0896-0267 (Print) 1573-6792 (Online)

Issue Volume 5, Number 4 / June, 1993

DOI 10.1007/BF01128698

Pages 399-412

Subject Collection Biomedical and Life Sciences

SpringerLink Date Tuesday, February 08, 2005

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F. H. Duffy1

, G. B. McAnulty1, K. Jones

2, H. Als

3 and

M. Albert4

(1) Department of Neurology, Childrens Hospital and

Harvard Medical School, 300 Longwood Avenue,

02115 Boston, MA, USA

(2) Florence Heller Graduate School for Advanced Studies

in Social Welfare, Brandeis University, Waltham, USA

(3) Dept. of Psychiatry, Childrens Hospital and Harvard

Medical School, Boston, USA

(4) Depts. of Psychiatry and Neurology, Massachusetts

General Hospital and Harvard Medical School, Fruit

Street, Boston, USA

Accepted: 8 March 1993

Summary We explore relationships between brain

electrical activity and cognitive performance where qEEG

data are correlated with psychological variables gathered at

a different time. For a population of 202 healthy adults using

univariate and multivariate correlation techniques in a split

half replication design, we confirm prior findings that

subjects with better psychological scores show shorter

evoked potential (EP) latency, suggesting that speed of

processing is an important factor in cognitive performance.

By canonical correlation we demonstrate a consistent,

replicable relationship between electrophysiological and

behavioral data. We suggest that reliance upon univariate

correlation may have fueled early controversies about

relationships between electrophysiology and IQ. In addition

we correlate psychological factors with the entire qEEG

data set (both EP and spectral analyzed EEG) and

demonstrate the use a multidimensional image graphics

techniques to assist in visual assessment of the resulting

correlation matrices.

Key words Evoked potentials - EEG spectral analysis - Behavior - Factor analysis - Canonical correlation - Split half replication - Correlational SPM

This work was supported in part by NIA program project

PO1AG049853 to M. Albert and the Mental Retardation

Program Project P30HD18655 to J.J. Volpe. We thank our

qEEG technologists Adele Mirabella, Susan Katz, Ellen

Belles and Marianne McGaffigan as well as our research

secretaries for their unflagging support. We thank Sandra

Kosta for her analytic help, Dr. Cary Savage for his

programming assistance, and Dr. Kristin Harris of the Image

Graphics Laboratory at Childrens Hospital for her aid with

3D image construction.

American Journal of Clinical Nutrition, Vol 64, 388S-396S, Copyright © 1996 by The American Society for Clinical Nutrition, Inc

ORIGINAL RESEARCH COMMUNICATIONS

Whole-body impedance--what does it measure?

KR Foster and HC Lukaski Department of Bioengineering, University of Pennsylvania, Philadelphia 19104-6392, USA. kfoster@eniac.seas.upenn.edu

Although the bioelectrical impedance technique is widely used in human nutrition and clinical research, an

integrated summary of the biophysical and bioelectrical bases of this approach is lacking. We summarize

the pertinent electrical phenomena relevant to the application of the impedance

technique in vivo and

discuss the relations between electrical measurements and biological conductor volumes. Key terms in

the derivation of bioelectrical impedance analysis are described and the relation between the

electrical

properties of tissues and tissue structure is discussed. The relation between the impedance of an object

and its geometry, scale, and intrinsic electrical properties is also discussed. Correlations between

whole-

body impedance measurements and various bioconductor volumes, such as total body water and fat-free

mass, are experimentally well established; however, the reason for the success of the impedence

technique is much less clear. The bioengineering basis for the technique is critically presented

and

considerations are proposed that might help to clarify the method and potentially improve its sensitivity.

An investigation of methods of measurement of the electrical phenomena of the skin

Journal Psychiatric Quarterly

Publisher Springer Netherlands

ISSN 0033-2720 (Print) 1573-6709 (Online)

Issue Volume 7, Number 1 / March, 1933

DOI 10.1007/BF01572720

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Pages 107-114

Subject Collection Medicine

SpringerLink Date Tuesday, May 10, 2005

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Carney Landis and T. W. Forbes1

(1) Department of Psychology, New York State Psychiatric Institute and Hospital, New

York, N. Y.

Summary We have shown that it is reasonable to expect from the nerve sectioning studies

on resistance of the skin and on the galvanic reflex, that a valid, standard technique can be

worked out to give an index of sympathetic nerve reactivity, but that a systematic study of

techniques and of the relationship between measures is a necessary first step toward such

a measure if it is to be valid. Our experimental results indicate that curves for basic

resistance vary with location of skin area and with technique used. Measurements with an

ordinary standard Wheatstone bridge and a source of 1 1/2 volts gave no indication of a

relationship to the functions under nervous control. Richter's technique was apparently

more sensitive in that it shows a greater range of variation, though we are not yet satisfied

as to the exact nature of the electrical phenomena which the technique measures. We plan

to make a more extensive study with simultaneous measures and to use still other

techniques.

In closing we wish to stress two points which we have raised in this paper. First, that

resistance and galvanic reflex curves from differing techniques cannot be assumed to be

comparable until shown to be so; and second, previous experimental and clinical studies,

indicate that valid measures of electrical skin phenomena when developed should provide

valuable indices of neurological and physiological functions.

AAQBT

The American Academy of Quantum

Biofeedback Technology

Located in Rio Rancho, New Mexico since 1988

Alarm Response

By William Nelson

ABSTRACT: Situated on a golf course in New Mexico the Land of Enchantment, in the City of Vision Rio

Rancho the AAQBT made history. We tested 935 subjects in Denver and New Mexico to understand the

basic body electric measures to better understand the nature of the energetic medicine. We need to

develop electrical profiles that indicate alarm reaction from the patient. The mathematical factor of

Ohms law states the Volts=Amps times Resistance. It would be theoretically impossible for a contained

system to have all three factors increase. When one rises such as volts amps would drop. For all three to

increase would be difficult. But we found that when a patient reacts adversely to a stimulus then all

three vectors can increase. This is part of a defense shield people have to stop electrical stimulation

from upsetting body process. This is needed in a world of electrical stimulation or a small snap of an

electric spark could be devastating. We found a statistical profile on the subjects to indicate an alarm

response to a stimulus that might be too much for the body. A simultaneous increase of the VAR

indicators of the extremities could be a measureable indictor for discontinuing a stimulus automatically.

The Alarm response could be a valuable addition to our cybernetic loop.

A brief History of the SCIO technology

By Desire’ Dubounet

In 1969 we landed on the moon and I worked on the navigation system for NASA as an employee of AC

Electronics. We made the beryllium gyro. I theorized about the trivector nature of electronics and the

body electric. Was trained to work on the punch card computer system, the IBM 360, but it had a flaw.

The square root of 2 was not accurate. I used a slide rule to do the work on Apollo 13 reentry.

In 1974 I did the first studies on the trivector idea with on a polygraph at YSU. Gerry Ford was president

and the computer mouse was just invented. I was trained on SPSS statistics computer programing.

I developed the EPFX system in 1985-89. The FDA accepts the registration of the EPFX on Oct 13 1989

and accepts the Electro-Physiological-Reactivity (EPR) measure of nosodes, allersodes, isodes, sarcodes,

and phyto substances. The EPFX had 8 channels every 100th of a sec. it was made to work on the 80-88,

or an 80-386 computer which can be seen only in a museum now. We did not have internet, fax was the

big thing, and a 10 Meg hard drive was considered large. Ronald Regan was president, a gallon of gas

was 1 dollar, and a movie ticket was $2.50. There was an iron curtain separating Europe.

In 1991 I patented the test kit system to make the quantum coherency analyzer. This improves the

accuracy of the system. President Geo Bush Senior and Gorbachev ended the cold war.

In 1992 I move to Budapest and further develop the EPFX. The system does not have the QQC trivector

readings in the hard drive and it does not have the subspace link. This software depends on the test kit

solely. This stolen software later becomes the Life system and without the test kit it does not function.

The life system is later found to measure nothing as was exposed as fraudulent in its biofeedback claim.

The life system does NOT have the subspace or the QQC trivector patterns and it is a fraudulent sham

counterfeit non-functional copy of the QXCI.

The QXCI is a technology I developed in 1996, it was revolutionary and made to run on a computer with

an 8 bit processor. I was designed to work on a parallel port. These computer technologies are now

obsolete and ancient. Would you buy a computer sold in 2002, answer no. a 2002 computer is junk

today. The QXCI ran on 12 channels every 500th of a sec. and the QXCI uses the computer timing chip for

operation, it does not have its own chip. The QXCI operates on digital signals so it is limited to a variant

square wave. The QXCI cannot make the complete waveforms of the SCIO. Bill Clinton is President and

the Beatles second reunion song is released. I develop the QQC device and I am able to put the trivector

readings into the computer. I develop the first Subspace system to work if no biological entity is

detected in the harness.

In 2003 it was time for advancement, progress, growth, improvement, transition. I designed the SCIO

with its own timing chip and its own computer inside. It was deigned on 16 bit use. It had 238 channel

every 100th of a sec. it was a dramatic advance. There are literally hundreds of thousands of

improvements made to the system since we started. Everyday some improvement is considered, tested

and made. All ways we work with the full legal and compliant regulations. Our new book shows over 200

publications of the technology and the history of research.

Advances in the SCIO make it faster and much better than the QXCI and some things like emotions just

become impossible with the QXCI. But some people do not understand advancement, progress, growth,

improvement, up grading. They live in the past till they need a computer then they don’t want to buy a

80-386, they say “Wait I am Not That stupid to buy an 386 computer , I want today’s technology” but

they are perfectly capable treating a patient with an old antiquated QXCI. They want today’s technology

but don’t want to upgrade to it.

Now the new “Eductor” is about to be released. This is a dramatic advancement in the EPFX, QXCI, SCIO.

It has three more wave form generators; it is usb technology and can operate at micro sec speeds. The

word doctor comes from the Latin word for teacher, eductor. This new technology is a new

advancement in our focus on development and it will be the future of our medical use. Only licensed

therapists or doctors can use one or students of the 12 month course. The anticipated price will be

about 18,000 euros.

So you see progress and technology move forward