Name

Human Physiology Lab Manual

Biology 219

Daniel Clemens

2020-21

i

Human Physiology Lab Manual

TABLE OF CONTENTS

Introduction ......................................................................................................................... ii

Exercise 1. Scientific Measurement and Data ................................................................... 1

Appendix A. Representative Values of Common Physiological Variables ................... A-1

ii

Introduction

The exercises in this manual are designed to reinforce the concepts covered in physiology

lecture and to provide hands-on experience performing physiological measurements and

lab procedures. The labs are not simple “cookbook” exercises, but require that you think

about what you are doing and understand how your observations in the lab are connected

to the underlying principles of physiology.

In order to maximize your success in the lab, it is important that you come prepared to

each lab session. Read the assigned exercise and review the pertinent topics in your

textbook before you come to lab. If you have questions about any of the procedures or

concepts, please ask your instructor before proceeding with the exercise.

Your instructor will review the lab safety and hygiene procedures during the first class

meeting (see pages iii-iv). Prior to each exercise, be sure you understand how to operate

the laboratory equipment to be used and be aware of potential hazards such as sharp

objects, electric current, or hazardous materials. Take good care of the lab instruments

and equipment, and leave the lab as clean or cleaner than you found it.

Finally, make the most of your time in the lab. Be curious, engage your mind, and

participate actively in all the lab exercises.

Acknowledgements

Some of the exercises in this lab manual were modified from Stuart Ira Fox, A Laboratory

Guide to Human Physiology, 13th edition, and from Elaine Marieb, Human Anatomy &

Physiology Laboratory Manual, 6th edition. Dr. Bonnie Moore developed procedures for

the Concentration and Dilution exercises and contributed to the Spirometry and Urinalysis

exercises. Dr. Alysia Thomas contributed material for the Membrane Potential, ECG, and

Acid-Base exercises. We would also like to thank Dr. Susan Wilson at Santa Rosa Junior

College for the use of material from her Human Physiology Laboratory Manual.

Microscopy images and photographs of anatomical models in this manual were created by

the author and are the property of Napa Valley College. Sources of other images and

diagrams are cited where applicable.

This manual was developed solely for the use of the students and instructors of Human

Physiology (Biology 219) at Napa Valley College. It is not intended to be sold or

distributed to the public. Any mistakes in this lab manual are the responsibility of the

author and the NVC Biology Department. Please let us know of any errors, omissions, or

suggestions for improvements so that we can correct them in future editions.

Dr. Dan Clemens

August 2020

iii

Laboratory Safety Rules

Your participation in this laboratory requires that you follow safe laboratory practices. You are

required to adhere to the safety guidelines listed below, as well as any other safety procedures

given by your instructor or the instructor(s) in charge of the course. You will be asked to sign a

form certifying that you were informed of the safety guidelines and emergency procedures for

this laboratory. Violations of these rules are grounds for expulsion from the laboratory.

Note: You have the right to ask questions regarding your safety in this laboratory, either directly

or anonymously, without fear of reprisal.

• Locate emergency shower and eyewash station. Locate the fire extinguisher and fire alarm.

• The Material Safety Data Sheets (MSDS) contain information on all known health hazards of

the chemicals used in this course. In addition, there is information concerning the cleanup of

spills and the accidental exposure to the chemical (e.g. skin contact or inhalation). You are

advised to inspect the contents of the MSDS binder located in the Instructional Assistant’s office.

• Dispose of all broken glassware, needles and scalpel blades (sharps) in the specially marked

receptacle. Never place any of those items in the trash can.

• Dispose of all animal material in designated plastic waste bags.

• Exercise care in working with surgical instruments. Notify you instructor immediately if you

receive any type of injury in the laboratory no matter how slight.

• Never pipette fluids by mouth. Pipetters will be available for your use. Check odors

cautiously. Never taste a chemical.

• Do not drink water from the taps in the laboratory.

• Shoes must be worn in the laboratory. Do not wear open-toed shoes or sandals.

• We suggest that you do not wear loose long sleeves, and wear a lab coat. If you have long hair,

we suggest that you tie it back so that it cannot fall into your work.

• Children and pets are not allowed in the laboratory.

• College regulations prohibit eating or drinking at laboratory tables. If you wish to bring

food/drink to lab, it must be stored in a designated “clean” area and eaten outside the lab.

• Wash hands before and after working in the lab. Wear gloves as needed.

• Turn off the Bunsen burner when you are not using it.

• If any hazardous reagents are spilled, notify your instructor at once.

• Before obtaining any reagents, carefully read the labels on the bottles twice. Many chemicals

have similar names. Never return unused chemicals to the original dispensing bottle.

iv

• Follow the instructor’s directions for disposal of chemicals. When no specific directions are

given, dispose of non-hazardous, water-soluble substances in the sink, and put insoluble materials

such as filter paper in the wastebasket.

• Perform only the experiment assigned; do not experiment on your own. No unauthorized

experiments are allowed.

• Every chemical in a laboratory must be properly labeled. Many chemicals have similar names

and you should read the name twice. If a chemical is a solution, the concentration will also

appear on the label. Solution concentration is commonly described by molarity (e.g., 6M HCl) or

by percent concentration (e.g., 0.9% NaCl).

• Use the proper instrument (eye-dropper, scoopula, etc.) to remove reagents from bottles. Do

not cross contaminate reagents by using the same scoopula for 2 different reagents.

• All biohazardous materials are to be disposed of in the special biohazard receptacle.

• All biohazardous spills are to be reported to the instructor or to the instructional assistant and

are to be cleaned up using disinfectant and disposed of properly.

be cleaned up using disinfectant and disposed of properly.

ADDITIONAL SAFETY MEASURES FOR IN-PERSON LABS DURING COVID-19 PANDEMIC

• If you have a fever, cough, or any other symptom consistent with Covid-19 disease, do not come to class. Any missed lab exercise can be made up online.

• Wash hands thoroughly before entering the lab, before and after touching any specimen or model, and before leaving the lab.

• All students must wear face masks at all times in the laboratory classroom. Disposable masks will be provided in the lab. The mask must fit properly, snugly on the face and completely covering the nose and mouth at all times. If a student wishes to use their own mask, it must be a one-time use N-95 or surgical-grade mask. Homemade or cloth masks are not acceptable.

• To the extent possible, students shall practice social distancing during labs and maintain a minimum distance of six feet from other students and from the instructor.

• For the dissection exercises, students will work individually on their own dissection specimen. Disposable gloves must be worn during all dissections and will be provided in the lab.

• At the end of each dissection lab, clean, rinse and dry all dissection tools using a disinfecting cleaning solution and warm water. Store your specimen in a sealed plastic bag labeled with your name and place it in the designated specimen cabinet. Clean your work area thoroughly with cleaning solution.

• Dispose of your mask after exiting the classroom in the designated biohazard waste container.

1

Exercise 1. Scientific Measurement and Data

This exercise covers basic principles of scientific measurement and data analysis,

including units of measurement, conversion between different units, and graphing of

scientific data.

Materials

calculators

rulers with metric units

graph paper

Introduction

In the physiology laboratory, you will be measuring and analyzing many different types

of scientific data from your lab experiments. Scientific measurement is an essential part

of physiology. To understand the function of the human body, it is important not only to

describe biological processes, but also to quantify the physical and chemical variables

that affect body function. This exercise will introduce some important concepts and

quantitative skills needed to make accurate measurements and analyze scientific data.

First, some definitions (from Merriam-Webster’s Online dictionary, 2009):

data - factual information (as measurements or statistics) used as a basis for reasoning,

discussion, or calculation.*

variable - a quantity that may assume any one of a set of values.

unit - a determinate quantity (as of length, time, heat, or value) adopted as a standard

of measurement.

* the word data is plural when referring to a set of measured values as in “the data are conclusive.”

Most physiological data are numerical values of biological variables such as body

temperature or concentration of a substance in the blood. As a rule, physical variables

must have specific units associated with them. A measurement value without a unit is

meaningless (with a few exceptions, such as pH and specific gravity). Some units are

simple, such as length in meters (m) or time in seconds (s); other units are compound,

such as concentration in grams per deciliter (g/dL) or heart rate in beats per minute

(beats/min). A familiar example from chemistry is the unit of molarity (M) which stands

for “moles per liter.”

For this class, you will need to become familiar with commonly used units of

physiological variables and be able to perform basic mathematical operations with

physical and chemical quantities, including conversions between different units. In

addition, you will need to know common methods of graphing data and be able to

interpret graphed data.

2

In this exercise, you will:

• review the metric system

• make standard conversions between different units

• perform basic mathematical operations with ratios and proportions

• calculate average values and graph a physiological data set

The Metric System

Scientists usually use the metric system to quantify physical and biological variables.

The metric system uses units that are based on the decimal system and are related to each

other by some power of ten, which greatly simplifies calculations and conversions. The

modern system of metric units is referred to as the International System of Units (SI).

Physiologists use the SI system for most measurements, but some non-SI units are still in

common use. Table 1.1 gives examples of units that are commonly used in physiology.

Table 1.1. Units Commonly Used in Physiology

Variable Units length (distance, height, diameter, etc.) m, cm, mm, m, nm

mass (weight) kg, g, mg, g

time s, min, h, day

volume L, mL, L

temperature C

concentration mM, mEq/L, g/L, g/dL, mg/mL, mOsm

pressure mm Hg, cm H2O, kPa

flow L/min, mL/min

frequency cycles/s (Hz), beats/min (bpm), breaths/min

electrical potential mV

energy kcal, kJ

The symbol for an SI unit often contains a prefix indicating the power of ten. Table 1.2

lists the SI unit prefixes that are most commonly used in physiology.

Table 1.2. Selected SI Unit Prefixes and Symbols

Prefix Symbol Multiplication Factor mega M 1,000,000 (106)

kilo k 1,000 (103)

deci d 0.1 (10-1)

centi c 0.01 (10-2)

milli m 0.001 (10-3)

micro 0.000001 (10-6)

nano n 0.000000001 (10-9)

pico p 0.000000000001 (10-12)

3

Unit Conversion

To convert between units with different prefixes, first determine the conversion factor

between the old units and new units. For conversions within the metric system. the factor

will be a power of ten (see Table 1.2); for example, 1 cm = 10-2 m = 0.01 m.

Since we are working with powers of ten, one way to do these conversions is by moving

the decimal point the appropriate number of places, that is, one place for each power of

10, but be sure to move it in the correct direction! The rule to remember is that a smaller

unit will have a larger numerical value (move the decimal point to the right) and a larger

unit will have a smaller numerical value (move the decimal point to the left).

The line below can help to visualize this:

I I I I I I I I I I I I I

k base d c m n

Each tick mark represents one decimal place to move when converting between unit

prefixes.The “base” is the unit with no prefix (such as g or L).

Example 1: Convert 8 cm to mm.

Since mm is a smaller unit than cm by one power of ten, move the decimal point one

place to the right: 8.0 cm = 80 mm.

Example 2: Convert 500 mL to L.

In this case, L is the larger unit by three powers of ten, so move the decimal point

three places to the left: 500 mL = 0.5 L.

For more complicated conversions, the method of equivalent fractions is useful and ensures

correct results. For each unit conversion, set up an equivalent fraction between the units,

that is, a ratio of the old and new units that is equal to one. Then multiply by the conversion

ratio(s) so that the old units cancel out, leaving the new untis. This is demonstrated in the

following examples.

Example 3: Convert 5000 mm into meters.

Step 1 - Write a ratio of the two units that is equal to one (the conversion ratio), so

that the new unit (m) is in the numerator and the old unit (mm) is in the denominator.

1 m = 1000 mm, therefore, = 1

Step 2 - Multiply the value to be converted by the conversion ratio and do the math.

5000 mm x = = 5 m

Notice that the old units (mm) cancel out, leaving the new units (m).

1 m

1000 mm

1 m

1000 mm

5000 m

1000

4

While the metric system is the standard for science and medicine, the “English system”

of measurements is still in common use in the United States. Table 1.3 shows some

conversion factors between metric system and English system units.

Table 1.3. Equivalence Between Metric Units and English Units

Quantity

Metric

(SI) Unit

English

Equivalent

English

Unit

Metric

Equivalent

Length 1 meter = 39.4 inches 1 inch = 2.54 cm

1 meter = 3.28 feet 1 foot = 0.305 m

1 km = 0.621 mile 1 mile = 1.61 km

Mass (weight) 1 gram = 0.035 ounces 1 ounce = 28.3 g

1 kg = 2.20 pounds 1 pound = 0.454 kg

Time 1 minute = 60 s

1 hour = 3600 s

Volume 1 liter = 1.057 quarts 1 quart = 0.946 L

1 liter = 33.8 ounces 1 fluid ounce = 29.6 mL

Temperature C = (F – 32) / 1.8 F = (1.8 x C) + 32

Example 4: Convert 150 pounds into kg.

Step 1 - Set up the conversion ratio so lbs will cancel out:

Step 2 - Do the math: 150 lbs x = 68 kg

Example 5: Convert 60 miles per hour into meters per second.

This example requires two conversions: from miles to meters and from hours to seconds.

Note that we want seconds to end up in the denominator (remember that “per” means

“divided by”), so we need to set up our conversion ratios correctly.

Step 1 - Set up the conversion ratios:

Step 2 - Do the math: x x x = 27 m/s

Significant Figures

The number of significant figures indicates the precision with which a number has been

measured or estimated. There are established rules for the number of “sig figs” to report,

but as a general rule, report only as many significant figures as can be measured accurately

and no more than are meaningful. For example, if you measure heights of students in the

class and calculate the average equal to 167.643 cm, you should report 167 cm, since your

data were measured only to the nearest cm (and fractions of a cm are not meaningful in this

case). In physiology, two to three sig figs is usually sufficient, for example, body

temperature = 37.2C or pH = 7.41.

1.61 km

1 mile

1000 m

1 km

1 hr

3600 s

60 miles

1 hr

1000 m

1 km

1.61 km

1 mile

1 hr

3600 s

1 kg

2.2 lbs

1 kg

2.2 lbs

5

Ratios and Percents

A ratio is a mathematical expression that relates two quantities by division. Many kinds of

scientific data are expressed as ratios. Ratios are often used to compare two quantities (for

example, the number of computer stations to the number of students in Physiology class).

When using ratios to compare quantities, the two quantities must have the same units. One

cannot compare the weights of two animals if the first is expressed in pounds and the second

is in kilograms. (Note, however, that you can use ratios with different units to convert

between units, as described above.)

A percent is essentially a ratio multiplied by 100. For example, the ratio 40/50 = 0.8, and

0.8 x 100 = 80%. When using percent to compare one quantity to another, calculate the

ratio with the value of interest (the “observed value”) in the numerator and the value to

compare it to (the “reference value”) in the denominator, then multiply by 100.

To calculate percent change or percent difference, first calculate the difference between

the observed value and the reference value by subtraction, then divide the difference by

the reference value and convert to percent:

Percent change = (observed value – reference value) x 100

(reference value)

If the calculation yields a positive number, then it is a percent increase; if it yields a

negative number, it is a percent decrease.

Example 6: After going on a diet for six months, Betty’s weight went from 90 kg to 72 kg.

What was the percent change in Betty’s weight?

Percent change = (72 kg – 90 kg) / (90 kg) = – 0.2 x 100 = 20% decrease

Proportions

The term proportion is sometimes used as a synonym for ratio, but it also has a more

specific meaning in mathematics. A mathematical proportion is an expression of equality

between two ratios, as in: A = C B D

Proportions are often used to solve for an unknown quantity. If three of the quantities are

known, the fourth can be calculated by cross multiplication, i.e., A x D = B x C. For

example, if a muscle contraction is recorded on a chart moving at a speed of 50 mm/s and

the trace covers 5 mm, you can determine the duration of the contraction (x) using a

proportion as follows:

50 mm = 5 mm

1 s x

Cross multiply and solve for x: 50 x = 5, x = 0.1 s

6

Average Values

Scientific data analysis often includes calculation of the arithmetic average or mean

value. The sample mean (X) is calculated as the sum of the values in a set of numbers

divided by the number of values (n = sample size). In mathematical terms:

X = Σ(x) / n.

Average values are useful for summarizing data and for comparing between groups.

Many scientific studies test whether there is a significant difference in the mean value of

a variable between two groups (say between a treatment group and a control group). This

involves using statistical analysis, which is beyond the scope of this exercise.

Physiological values from an individual are often compared with the population mean or

“normal” value. Normal physiological values will be referred to often during the course;

however, because physiological data are naturally variable, in practice it is more correct

to refer to a normal range of values for a physiological variable. Values that deviate

markedly from the normal range may indicate physiological dysfunction or disease.

When we collect data from humans in the laboratory, the natural variation that exists is

compounded by the fact that the data will be collected by many different observers with a

wide range of skills. Therefore, we do not expect most of our data to show statistically

significant differences, we will only be noting trends or suggestions of differences.

Graphs

Scientific data are often plotted in a graph to facilitate presentation and interpretation of

results. Graphs commonly used in the physiology lab include bar graphs, X-Y plots

(scatter plots and line graphs), and time traces.

A bar graph is often used to compare average values of a variable between different

groups; for example, blood cholesterol levels between a control group and a drug-treatment

group. Bar graphs are simple to construct and provide an easy-to-read, visual summary of

the data. You usually plot only one variable at a time on a bar graph, with the variable

along the Y axis (height of the bar) and the groups being compared along the X axis.

An X-Y plot is used to show the relationship between two variables. As a rule, the

independent variable is plotted along the X axis and the dependent variable along the

Y axis. The data may be plotted as separate points (a scatter plot) or as a line connecting

points (a line graph). Note that it is not always appropriate to connect the data points

with a line. Use a line graph to plot continuous data from the same individual or

experimental run. Use a scatter plot to graph points from different individuals in a

population or test group. In this case, the points should not be connected with a line, but

a “best-fit” line may be drawn through the data points to show the general trend.

A time trace is a type of X-Y plot that has time along the X axis and a measured variable

along the Y axis (see Figure 1). This is one of the most common kinds of graphs in

physiology.

7

Figure 1. Arterial blood pressure of a healthy, resting person.

For all graphs, it is essential to label your graphs and axes with the correct units. The

names of the variables for the X and Y axes are usually written along the axes (to the left

of the Y axis and below the X axis) with their units in parentheses. In a laboratory report

or scientific paper, a graph is called a figure. Each figure should have a title that includes

the figure number and a short caption that explains what the figure shows. Look through

your textbook to find examples of the three kinds of graphs described above.

Thought and Discussion Questions

1. Why is it important to include the correct units with a numerical value?

2. What is the main advantage of the metric system over the English system of measurement?

3. How are ratios used to convert between different units of measurement?

4. How many siginificant figures should you show in your data?

5. What are some advantages of using a bar graph to present data?

6. What information does an X-Y (or scatter) plot provide that the bar graph does not?

8

9

Exercise 1 Scientific Data Name

Problems and Questions

Part 1

1. Use a small metric ruler to measure the length of the line shown below. Record your

measurement in millimeters and in centimeters.

________________________________ ________ mm

________ cm

2. Record your weight in pounds and your height in inches; convert these measurements to

kilograms and centimeters.

weight: ________ lbs = ________ kg height: _______ inches = _______ cm

3. Compute the following conversions:

242 mg = g 345 mL = L

6.28 kg = g 25 L = mL

4 kg = lbs 10C = F

0.83 cm = mm 72 F = C

4. Solve the following proportions for x:

6/36 = x/48 x = _________ 0.9/36 = x/64 x = _________

24/144 = 18/x x = _________ x/24 = 3/60 x = _________

5. Julia’s resting heart rate is 75 beats per minute (bpm). While exercising on the treadmill, her heart

rate went to 126 bpm. Calculate the percent change in Julia’s heart rate.

6. The heart at rest pumps 5,000 milliliters of blood per minute (mL/min) through the systemic

circulation. Blood flow to the kidneys is approximately 1,200 mL/min at rest. Assuming that

blood flow to the kidneys is proportional to the total blood flow, what will be the blood flow to the

kidneys if the heart pumps 7,000 mL/min? (Hint: this is a proportion problem.) Show your work!

renal blood flow = ________________

7. An electrocardiogram is recorded on mm-grid chart paper moving at a speed of 25 mm/s. If the

recorded distance between each heart beat is 20 mm, what is the heart rate in beats per minute? (Hint:

use equivalent fractions to convert units, with 1 beat = 20 mm and 25 mm = 1 s.) Show your work!

heart rate = ________________

10

11

Exercise 1. Scientific Data Name

Problem Set

Part 2

The following table gives data for the time of gestation and birth weight of babies born to

healthy mothers and to alcoholic mothers.

GROUP A

Babies born to healthy mothers

GROUP B

Babies born to alcoholic mothers

Gestation (Days) Birth Weight (kg) Gestation (Days) Birth Weight (kg)

288 3.60 267 3.02

278 4.48 234 2.91

265 3.23 200 2.32

245 2.85 278 3.13

289 4.12 190 2.87

269 3.89 243 2.38

237 3.23 210 2.99

265 3.32 287 3.31

254 3.04 199 2.64

1. Calculate the average gestation time and average weight of each group of babies.

Group A: average gestation time ____________ days

average birth weight ____________ kg ____________ pounds

Group B: average gestation time ____________ days

average birth weight ____________ kg ____________ pounds

2. On a sheet of graph paper, plot two bar graphs, one that compares the average birth weight

between the two groups and a second bar graph that compares the average gestation time

between the groups. Label the graphs appropriately.

3. On a different sheet of graph paper, plot an X-Y scatter plot of the data (gestation time on the

X axis and birth weight on the Y axis). Scale and label the axes appropriately and use different

symbols to distinguish the two groups. Draw a best-fit line (with a straight-edge) through the

data for each group (there should be two lines), and label the lines.

Questions:

1. What do your graphs show about the effects of alcohol on birth weight and gestation time?

2.What additional information does the X-Y scatter plot show that the bar graph does not?

A-1

Appendix A. Representative Values of Common Physiological Variables

Variable Value* Units

Body temperature 37 °C

Arterial blood pH 7.4 (no units)

Plasma osmolarity 290 mOsM

Plasma Na+ concentration 140 mM or mEq/L

Plasma K+ concentration 4.5 mM or mEq/L

Resting membrane potential (neuron) – 70 mV

Plasma glucose concentration (fasting) 90 mg/dL

Arterial PCO2 40 mm Hg

Arterial PO2 100 mm Hg

Arterial O2 saturation 98 %

Plasma bicarbonate concentration 24 mM or mEq/L

Basal metabolic rate 1,700 kcal/day

Heart rate 72 beats/minute or bpm

Stroke volume 70 mL

Cardiac output 5,000 mL/min

Mean arterial blood pressure 90 mm Hg

Colloid osmotic pressure 25 mm Hg

Intrapleural pressure (at end expiration) - 4 mm Hg

Functional residual capacity 2,400 mL

Tidal volume 500 mL

Total ventilation (minute volume) 6,000 mL/min

Alveolar ventilation rate 4,200 mL/min

Hematocrit 45 %

Hemoglobin concentration 15 g/dL

Glomerular filtration rate 125 mL/min

* approximate average values for a healthy, 70 kg male at rest.