instructor terry wiseth. organization of nervous system

Instructor Instructor

Terry WisethTerry Wiseth

Organization Of Nervous

System

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Principle Parts Of The Brain

Adult brain100 billion

neurons3 pounds

1) cerebrum2) diencephalon3) brain stem4) cerebellum5) cerebrospinal fluid and ventricles

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Brain Stem

Medulla oblongata

Midbrain

Pons

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Diencephalon

Thalamus

Hypothalamus

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Cerebrum

Cerebral hemispheresLeft and right sides

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Cerebellum

Second largest part of the brain

shaped like a butterfly with cerebral hemispheres

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Protection And Coverings

skullcranial meninges

continuous with the spinal meningesdura materdura materarachnoidarachnoidpia materpia mater

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Cerebrospinal Fluid

CSFcirculates

throughsubarachnoid subarachnoid spacespace

ventriclesventriclescavities in the brain

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Cerebrospinal Fluid

Clear, colorless fluidNourish, protect brain

GlucoseProteinsLactic acidUreaCationsAnionsLymphocytes

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Cerebrospinal Fluid

Functions1) shock absorbing2) chemical protection3) circulation

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Ventricles

CSF filled cavities in brain

Continuously circulates through the subarachnoid space and spinal cord and through cavities within the brain

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Ventricles

CSF filled cavities in brain

Continuously circulates through the subarachnoid space and spinal cord and through cavities within the brain

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Choroid Plexuses

Networks of capillaries in walls of the ventricles

Source of cerebrospinal fluid as it oozes from the capillaries

Normally CSF is reabsorbed as rapidly as it is formed 480 ml/day

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CSF

Absorption of the CSF into the blood stream takes place in

the sagittal sagittal sinussinus through structures called arachnoid villiarachnoid villi

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CSF

When the CSF pressure is greater than the venous pressure

CSF will flow into the blood stream

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CSF

However, the arachnoid villi act as "one way valves”

if the CSF pressure is less than the venous pressurethe arachnoid villi

will NOT let blood fluid pass into the ventricular system

CSF Low

Venous High

CSFCirculatio

n

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Hydrocephalus

Obstruction or inflammation in brain can interfere with drainage of CSFEx. Tumor, congenital blockage

Accumulating fluids raise CSF pressure causing bulging heads and compressed nerve tissue in brain

Implant drain courses from the ventricle to subclavian veins which release pressure

Hydrocephalus

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Blood Supply

Brain consumes 20 % of the O2 volume while the body is at rest

Amount of O2 utilized varies with the degree of mental activity

1-2 minute interruption in blood flow may impair brain cells

Brain cells deprived of O2 for over 4 minutes are permanently damaged

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Blood Supply

Lysosomes present in brain cells are sensitive to decreased O2 concentration

Lysosomes may break open releasing enzymes destroying the brain cell

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Brain Injuries

Damage to brain can result from trauma due to impact and release of oxygen free radicals (charged O2) from damaged cellsFree radicals cause

damage by disruptingcellular DNA andenzymes

Brain cells recoveringfrom stroke alsorelease free radicals

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Blood Supply

Carbohydrate storage is limited in brain cells thus supply of glucose must be continuous

Glucose, O2, CO2, H2O, alcohol, caffeine, nicotine, heroin, anesthetics pass readily from bloodstream into brain cells

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Blood Supply

Creatinine, urea, Na+, K+, Cl- enter brain cells much slower

Proteins, antibodies do not pass at all from blood into brain cells

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Blood Brain Barrier

BBBCapillary linings of blood vessels in

the brainLess “leaky” than other body

capillariesAstrocytes (neuroglia) able to select

to some degree which substances pass from the blood into the brain cellsImportant to protect brain from

harmful substances and pathogens

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Blood Brain Barrier

Injury to brain can cause breakdown in BBB

Small regions of brain in 3rd and 4th ventricle called circumventricular organs (CVOS) lack BBB and can monitor chemical changes in blood

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Yawn

We yawn when nerves in the brain stem find there's too much carbon dioxide in the blood

A yawn makes the muscles in our mouth and throat contract and forces our mouth wide openallowing us to expel

carbon dioxide andtake in a large amountof oxygen-rich air

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CVOS

Hypothalamus, pineal gland, pituitary glandAble to

coordinate activities of endocrine and nervous systemEx: BP, fluid balance, hunger, thirst

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Brain Stem

1) midbrain

2) pons

3) medulla oblongata

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Brain Stem

1) midbrain

2) pons

3) medulla oblongata

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Medulla Oblongata

Continuous with upper part of spinal cord

Most tracts cross at the upper part of the spinal cord

Tracts from left side lead to right side of the brain (sensory and motor)

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Medulla Oblongata

Regions within the medulla1) regulate rate and force

of heartbeat2) regulate diameter of

blood vessels3) regulate basic rhythm

of breathing4) coordinate swallowing,

vomiting, coughing, sneezing, hiccuping

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Medulla Oblongata

Associated with the medulla are regions which also control1) efficiency of precise, voluntary

movements2) maintenance of

equilibrium and posture3) cranial nerves VIII-XII

Hard blows to back of heador neck can be fatal

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Pons

Bridge connecting the spinal cord with the brain

Bridge to connectleft and right sidesof the brain

Cranial nerves V-VIII

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Midbrain

Reflex centers for movement of eyes, head, neck is response to visual and auditory stimuli

Controls subconscious activities

Convey information from lower brain centers to higher brain centers

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Midbrain

Reflex centers for movement of eyes, head, neck is response to visual and auditory stimuli

Controls subconscious activities

Convey information from lower brain centers to higher brain centers

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Diencephalon

ThalamusHypothalamusThalamus

Hypothalamus

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Thalamus

Principle relay station from sensory impulses that reach the cerebral cortex from the spinal cord, brain stem, cerebellum and other parts of the cerebrum

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Thalamus

Crude sensations of pain, temperature, pressure

Some voluntary motor actions, arousal, emotions, and memory are relayed through the thalamus

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Hypothalamus

Lacks a blood-brain barrier

Major regulation of homeostasis

Controls and integrates activities of the autonomic nervous system (ANS)

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Hypothalamus

Associated with emotions of rage and aggression

Regulates Heart ratePeristalsisGlandular

secretionsBladder controlBody

temperature

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Hypothalamus

Regulates food intake Hunger and satiety

centersRegulates water intake

Thirst centerRising osmotic pressure

sensation of thirstMaintains waking state

andsleep patterns

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Cerebrum

Forms the bulk of the brain

Cerebral cortex

Limbic system

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Cerebrum

Forms the bulk of the brain

Cerebral cortex

Limbic system

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Cerebral Cortex

Surface of the cerebrum 2-4 mm thick

Composed of gray matter

Cerebral white matter lies beneath the cerebral cortex

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Cerebral Cortex




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Cerebral Cortex




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Cerebral Cortex

Cerebrum partially divided longitudinally into left and right hemispheres

Each cerebral hemispheres is further subdivided into four lobes FrontalParietalTemporalOccipital

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Cerebral Cortex

Cerebrum is seat of intelligenceAbility to read,

write, speak, calculate, compose music, memory, plan for the future, create

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Limbic System

“Emotional brain”Ring of structures encircling the

brain stem

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Limbic System

Functions in emotional aspects of behavior related to survivalMay also have some functions in

memory of strong emotionsAssociated with pleasure, pain,

rage, anger, fear, sorrow, sexual feelings, docility and affections

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Functional Areas

1) sensory areasReceive and interpret sensory impulses

2) motor areasControl muscular movement

3) association areasDeal with complex integrative

functions, memory, emotions, reasoning, will, judgement, personality, intelligence

FunctionaFunctionall

Areas Areas

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Sensory Areas

Input flows mainly to posterior half of the hemispheres to primary sensory primary sensory areaarea

Secondary Secondary sensory sensory associationassociation areas are adjacent to primary area

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Secondary Sensory Areas

Receive input from them interpreting sensory experiences into meaningful patterns of recognition and awareness

Ex: damage to primary visual area may lose part of their visual field

Damage to visual association area may see normally yet be unable to recognize a friend

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Sensory Areas

General sensory area

Primary visual area

Primary auditory area

Primary gustatory area

Primary olfactory area

SensorSensory Areasy AreasGeneral sensory area

Primary visual area

Primary auditory area

Primary gustatory area

Primary olfactory area

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General Sensory Area

1,2,3 Localizes exactly the

points of the body where sensations originate

Thalamus registers sensations in a general way

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Primary Visual Area

17Receives impulses

from thalamus containing information concerning shape, color, and movement

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Primary Auditory Area

41,42 Interprets basic characteristics of

sound (pitch, rhythm)

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Primary Gustatory

Area

43Receives impulses related to taste

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Primary Olfactory Area

Medial aspect of temporal lobeReceives impulses related to smell

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Motor Areas

Mainly anterior portion of each hemisphere generates outputsPrimary motor areaLanguage area

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Primary Motor Area

4Controls voluntary contractions of

specific muscles

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Language Area

44Motor speech area

Translation of thoughts into speech

Coordinated contractions of speech and breathing muscles

Translation of speech or written words into thought involves both sensory and association areas

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Association Areas

Consist of association tracts that connect motor and sensory areas and peripheral parts of the cerebral cortex

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Association Areas

Somatosensory association area

Visual association area

Auditory association area

Gnostic area

Premotor area

Frontal eye field

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Somatosensory Association

Area5,7

Integrates and interprets sensations

Determines exact shape and texture of an object without looking at it

Sense the relationship of inner body part to another

Also stores memories of past sensory experiences

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Visual Association

Area

18,19Receives sensory

impulses from primary visual area and the thalamus

Relates present to past visual experiences with recognition and evaluation of what is seen

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Auditory Association

22Determines a

sound is speech, music or noise

Interprets meaning of speech by translating words into thought

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Gnostic Area

5,7,39,40Common integrative

area of somatosensory, visual, auditory, taste and smell areas

Also receives impulses from thalamus and brain stem

Integrates information from sensory association area so that a common thought can be formed

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Premotor Area

6Concerned with

learned motor activities of complex and sequential natureEx. Write a word

Serves as a memory bank for learned skill movements

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Frontal Eye Field

8Controls

involuntary scanning movements of the eyesEx. Searching for a word in a dictionary

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Speech Area Injuries

Language areas are located in the left cerebral hemispheres

Aphasia Inability to speakInjury to sensory or motor

speech areas

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Nonfluent aphasia

Damage only to motor speech area

Inability to properly articulate

Person knows what to say but cannot speak

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Fluent aphasiaDamage to gnostic

or auditory association

Faulty understanding of spoken or written words

Producing fluently strings of words without meaning

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Word deafnessInability to understand spoken

words

Word blindnessInability to understand written

words

Hello How Are You

Hello How Are You

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EEG

Electroencephalogram (EEG)

Electrical impulses

Generation of nerve impulses collectively called brain waves

Record of brain waves called EEGEEG

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Brain Waves

Alpha waves

Beta waves

Theta waves

Delta waves

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Brain Waves

Alpha wavesPresent during wake and resting

stages with eyes closedBeta waves

Appear when nervous system is activeEx. Sensory input, mental activity

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Brain Waves

Theta wavesOccur in individuals experiencing

emotional stressMay also occur in

disorders of brain Delta waves

Occur during deep sleepNormal in an awake infantIndicate brain damage in an awake

adult

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EEG

Used to diagnose:EpilepsySeizure disordersTumorsInfectious diseaseTraumaHematomaMetabolic disordersDegenerative diseasesBrain death

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Brain Lateralization

Functional and anatomical differences between left and right hemispheres of the brainEx. Left-handed people

Parietal and occipital lobes of right hemisphere are narrower than corresponding lobes of left side

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Left hemisphereControls right side

of bodyMore important

for: SpokenWrittenNumerical andscientific skills

Reasoning

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Right hemisphereControls left side of

body More important for:

InsightImaginationMusical and artistic

awareness

Space and pattern perception

Generating mental images of sight, sound, touch, taste and smell to compare relationships

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Cerebellum

Subconscious movements of skeletal muscles, equilibrium

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Cerebellum

Functions to compare the intended movement determined by the motor areas with whatis actuallyhappening

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Cerebellum

If intent of motor area is not attained the cerebellum detects the variation and sends signals to motor areas of brain to inhibit or stimulate activity of skeletal muscles

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Cerebellum

Coordinates skilled movements

Regulates posture, balance

Ex. Dancing, catching a baseball

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Neurotransmitters

Approximately 50 substances act as neurotransmitters in the brain

Results of neurotransmitters can be excitation or inhibition of neurons

AcetylcholineAcetylcholine

Biogenic aminesBiogenic amines

Amino acidsAmino acids

NeuropeptidesNeuropeptides

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Acetylcholine

AChMay be excitatory or inhibitoryACh inactivated by

acetylcholinesterase (AChe)Major center of ACh release are

neurons which project through the cerebral cortex and limbic system

Destruction of these neurons occurs in individuals suffering from Alzheimer's disease

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Amino Acids

excitatory

glutamateglutamate

aspartateaspartate

inhibitor

gamma aminobutyric acid (GABA)gamma aminobutyric acid (GABA)

valiumvalium enhances action of GABA

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Biogenic Amines

can be either excitatory or inhibitory

Norepinephrine

epinephrine

dopamine

serotonin

histamine

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Biogenic Amines

DopamineInvolved in gross automatic movements of skeletal muscles

SerotoninThought to be involved in inducing sleep

Control of mood

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Neuropeptides

Largest family of neurotransmitters

May have either excitatory or inhibitory actions

Neuropeptides

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Enkaphalins

1974 found that certain brain cells have receptors for opiate drugsEx. Morphine, heroin

Quest to find the naturally occurring substances that use these receptors brought to light the neuropeptides

EnkaphalinsEnkaphalinsPotent analgesic effects200x stronger than morphine

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Opioids

Other opioids include endorphins and dynorphins

Opioids are the body’s natural pain-killers

Have been linked to improve memory, learning, feelings of pleasure, (euphoria), sexual drive, depression, schizophrenia

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Opioids

AnalgesicAnalgesic effects of acupuncture may be due to increased release of enkaphalins or endorphins

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Opioids

If someone unexpectedly pricks oneself

a message from the spinal cord is transmitted to the cortex of the cerebrum

which results in the first experience of pain

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Opioids

In order to prevent putting there hand into the sewing box just as carelessly on a second occasion and to introduce a moment of learning

stimuli are sent (slowly) from the spinal cord to the part of the brainstem where the opiate receptors are located

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Opioids

This area is responsible for the alarming or threatening aspect of pain this effect which is remedied so

effectively by the administration of opiates

The feeling itself does not disappear so much as lose its threatening character

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Opioids

It is this which lends the opiates their painkilling (analgesic) effecthas virtually no

effect whatever on the other sensory perceptions, consciousness or the motor functions

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Opioids

All other substances with a painkilling effect

laughing gas

alcohol

ether

barbiturates

have a effect on consciousness, motor coordination, the intellect and emotional control

Neurotransmitters

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Chocolate

The chemical phenylethylaminephenylethylamine

causes a slightly dreamy feeling produced by the brain when two

people fail in love

Interesting enough,the same chemicalcan be found inchocolate

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Cranial Nerves

12 pair of cranial nerves which originate in the brain

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Cranial Nerves

I) olfactorySmell

II) opticVision

III) occulomotorMovement of eyelid movement of eyeballaccommodation of

lens pupil constriction

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Cranial Nerves

IV) trochlearMovement of eyeball

V) trigeminalChewing mouthtongue= touch,

pain, temperature

VI) abducensMovement of eyeball

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Cranial Nerves

VII) facialFacial expression

secretions of saliva, tears taste (anterior 1/3 of tongue)

VIII) vestibulocochlearHearing, equilibrium

IX) glossopharyngealSecretion of salivaTaste (posterior 1/3 of

tongue)

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Cranial Nerves

X) vagusSmooth muscle

contraction and relaxation

Secrete digestive juices

Sensations from trachea, lungs, esophagus, heart, stomach, SI, LI, gall bladder

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Cranial Nerves

XI) accessorySwallowing head

movement

XII) hypoglossalMovement of

tongue during speech, swallowing

Cranial Nerves

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Disorders Of The Brain

StrokeAlzheimer’s diseaseBrain tumorsCerebral palsyParkinson’s diseaseMultiple sclerosisHeadacheDyslexiaReye’s syndrome

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Stroke

Cerebrovascular accident (CVA)

Most common brain disorder

1) ischemic- most common Decreased blood supply

blood clots, plaque build-up

2) hemorrhagic- rupture of blood vessel

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Stroke

Transient ischemic attack (TIA)Temporary cerebral

dysfunction caused by impaired blood flow to the brain

TIA persists for a few minutes and last 24 hours

Leaves no persistent neurological deficits

Stroke

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Alzheimer’s Disease

Alzheimer’s disease (AD)

Afflicts 11% of population over 65 years old

Progressive neuronal loss with associated loss of neural functions

Cause unknown Genetic ?Aluminum ?Virus ?

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Brain Tumors

Benign or malignant growth

Pressures affecting normal tissues produce characteristic signs and symptoms

Surgery

Radiation therapy

Chemotherapy

Brain Tumors

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Cerebral Palsy

Cerebral palsy (C)

Group of motor disorders resulting in muscular incoordination and loss of muscle control

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Cerebral Palsy

Caused by brain damage to motor area of the brain during fetal life, birth or infancy

Non-progressive disease

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Parkinson’s Disease

Parkinson’s Disease (PD)

Progressive disorder of CNS to elderly

Around 60 years old

Toxic environmental factors suspected as cause

Imbalance of neurotransmitters produce symptoms of PD

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Parkinson’s Disease

Involuntary muscle contractions interfere with voluntary movement

Treatment with dopamine (which is lacking in PD patient) does not work because dopamine will not cross the BBBLevodopa (l-dopa)Levodopa (l-dopa) treatment elevates

brain levels of dopamine and lessons the symptoms

Does not slow the disease Transplanting of fetal nerve tissue

(dopamine rich) into patients have shown some degree of improvement

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Multiple Sclerosis

Multiple sclerosis (MS)

Progressive destruction of myelin sheaths of neurons in the CNS

Slows and short circuits conduction of nerve impulses

Cause is unknown

No treatment

NormalAbnormal

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Multiple Sclerosis

Muscular weakness, visual impairment, vertigo are some of the symptoms

Sufferers experience attacks with periods of remission lasting up to two years

Viral infection has been implicated as a cause Initiates an autoimmune response in

which T-cells destroy the myelin producing cells

Immunosuppressive drugs are often given

Multiple Sclerosis

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Dyslexia

Impairment of brains ability to translate images into language

Distorted ability to read, write, count

Letters in words seem transposed, reversed or upside down

“Dog”...........“God” or “bog”

Oil...............710

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Dyslexia

3X more common in males than females

Left hemispheres more active than right hemisphere (language area)

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Headache

Causes may include

Brain tumors

Blood vessel abnormalities

Inflammation

Decrease in O2

supply to the brain

Infections of sensory organs and sinuses

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Headache

Analgesic, tranquilizing compounds effective for tension headache but not migraine

MigraineMigraine sufferers find some relief with:

Biofeedback

Dietary changes

Drugs which constrictblood vessels

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Reye’s Syndrome

Reye’s syndrome (RS)

Seems to follow a viral infection

Aspirins may be risk factor in the development of RS

Brain damage result of cerebral swelling

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Brain Quotes

Aristotle taught that the brain exists merely to cool the blood and is not involved in the process of thinking

This is true only of certain persons

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Brain Jokes

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Brain Jokes

“My girlfriend and I went on a picnic”

“I don't know how she did it, but she got poison ivy on the brain”

“When it itched, the only way she could scratch it was to think about sandpaper” Steven Wright

instructor terry wiseth. organization of nervous system

Documents

brain slide

pressure slide

brain cell slide

csf circulation slide

brain adult brain

hydrocephalus slide

damaged slide

mlday slide