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The NERVOUS SYSTEM. Central & Peripheral Nervous System.

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Central & Peripheral

Nervous System

You at a friend’s backyard party when her uncle starts to stumble, and complain of dizziness and tiredness. He is also having difficulty breathing. He mentions that he was spraying for insects in the front yard and may have breathed in too much spray. He sits and relaxes, but does not feel any better after 15 min. His blue complexion provides a good signal that you should take him to the hospital. On the way to the hospital, his muscles go from tense to limp. The emergency-room physician finds out that your friend’s uncle had a busy day before the party.

CSI #8 – Function of the Nervous System

He was involved in cleaning algae out of the large pond behind the house before spraying the yard. He ate some old beef stew that was in the refrigerator, but claims it didn’t look or smell bad. Your friend is concerned about her uncle and asks you to explain what the physicians are looking for as the cause to her uncle’s illness.

You explain that the physicians must use a process of elimination to determine what caused her uncle’s problems.

CSI #9 – Structure of the Nervous System

You just heard that a former professional football player living in your neighborhood was taken to the police station after a disturbance at a local grocery store. You find out that he was wandering around the store aimlessly and making aggressive comments as if he were drunk. A friend then calls to tell you that the football player was admitted to the hospital because he started having seizures. Later in the week, some neighbors tell you that the football player was showing signs of weakness and often acted confused during conversation. There were also some concerns mentioned about his excessive alcohol consumption and weight gain. Your friend asks you what might be wrong with the 50 year old former athlete.

Determine the possible nervous system problems causing the illness.



Nerve Structure

(membrane that surrounds the entire nerve)


(bundle of axons)

(bundle of



(membrane that surrounds each axon)

(membrane that surrounds each fascicle)


(transmit impulses

TO the cell body)


cell body (contains nucleus)

axon (transmit impulses AWAY from the cell body)

direction of nerve impulse

(space between

schwann cells)

(white fatty substance that protects the axon)

(cells that produce myelin;

(transmits impulses)

(receives impulses)

Axons in the brain/spinal cord lack a neurilemma so regeneration is much less than it is in the PNS.

(space btwn neurons

were impulses are transmitted)

Conduction of Impulses

  • action potential: a nerve impulse at a given point on an axon (neuron)

It takes 0.001 seconds to reset a neuron; can carry 1000 impulses/sec.

Action Potential Animation:

a. conduction along unmyelinated


b. conduction along myelinated fibers

Myelin and Multiple Sclerosis

  • auto immune disorder that destroys myelin (demyelination) & leads to impaired nerve conduction  called multiple Sclerosis (MS)

  • most common in women btwn 20 – 40

Neuron Physiology

  • neurotransmitters  chemicals by which neurons communicate

  • can assist, stimulate, or inhibit communication

  • Acetylcholine, Dopamine, and Serotonin = play a role in motor function, sleep, mood, and pleasure

  • Endorphins and Enkephalins = inhibit conduction of pain impulses (natural pain killers)


Have 2 different effects…

1) Excitatory: a stimulus that encourages an A.P.

2) Inhibitory: a stimulus that discourages an A.P.

4-stage process when communicating with neurotransmitters:

  • Synthesis and storage of neurotransmitters

  • (made in nerve cell body & stored in vesicles)

  • Neurotransmitter release

  • (influx of Ca during A.P. causes neurotransmitter release)

  • 3. Neurotransmitter binding to post-synaptic receptors

  • Inactivation of neurotransmitters

  • (cell inactivates neurotransmitters by degrading them in synapse

  • or re-uptake them for recycling.)

presynaptic neuron


postsynaptic neuron

Major Neurotransmitters in the Body

Drugs Interfere with Neurotransmission

Effects of Alcohol on the Brain

Spatial Summation

  • Are your fingers moving?

  • Are both your pant legs touching your knees?

  • Is your pinky toe touching the ground?

  • Are you wearing underwear?

  • Information is being sent to your brain ALL the time - but is shut off by inhibitory impulses.

Clear your Minds

Spatial Summnation works because you have both inhibitory and excitatory neurons working against each other

Threshold Stimulus – the minimal stimulus required

to evoke a response

  • All or None Response

B - 50 imp

C -10 imp

D + 30 imp

A +50 imp

cell body

A by itself = no transmission

A+D = transmission

A + B + D = no transmission


E + 30 imp

Threshold = 80 impulses / sec

  • endorphins are released by neurons in brain to inhibit pain/fear; reason we can calm ourselves down?

  • learn something new – synapse forms

  • forget something – synapse disappears

Concept Check #1

  • How do the Central NS & Peripheral NS differ?

    2. How do the sensory and motor neuron function in the NS differ?

    3. We know that the blood brain barrier separates the blood and nervous tissue but why is this important?

Concept Check #2

5. What is believed to be the cause of myelin

destruction in the auto-immune disease multiple sclerosis?

6. How do pre & post synaptic neurons differ?

7. Explain the direction in which nerve impulses

travel? (use the terms axon, dendrite, pre & post synaptic neurons)

8. What is a nerve? What are the 3 layers of a nerve

and how do they differ?

Concept Check #3

9. What are neurotransmitters and how do they


11. What is an action potential? Finish the diagram

below. ++++ -+++ 

- - - - + - - - 

12. Explain how your brain can receive tons of

information but you only reacte or realize some of

them? (be sure to use threshold stimulus and inhibitory impulses in your answer)




The Brainstem

  • controls your vitals (heartbeat, respiration, b.v. diameter)

  • consists of midbrain, pons and medulla


  • 2nd largest part of the human brain

  • responsible for smooth coordinated movements, equilibrium, normal posture

The diencephalon (hypothalamus / thalamus)

  • Hypothalamus  controls all internal organs

  • Thalamus  regulates emotions

heartbeat, temp., peristalsis, appetite, sexual arousal; vol. of urine &H2O

The Cerebrum

  • largest and uppermost part of the brain

  • controls conscience thinking, memory,

    sensations, and emotions

4 Major Lobes of the Human Brain

Parts of the Cerebrum

cerebral cortex:

(surface of cerebrum)

(ridges of cortex))

(grooves of cortex)



deepest groove

of the brain

that separates the

brain into 2


LEFT BRAIN FUNCTIONSuses logicdetail orientedfacts rulewords and languagepresent and pastmath and sciencecan comprehendknowingacknowledgesorder/pattern perceptionknows object namereality basedforms strategiespracticalsafe

RIGHT BRAIN FUNCTIONSuses feeling"big picture" orientedimagination rulessymbols and imagespresent and futurephilosophy & religioncan "get it" (i.e. meaning)believesappreciatesspatial perceptionknows object functionfantasy basedpresents possibilitiesimpetuousrisk taking

Left Brain vs. Right Brain

Left vs. Right Hemisphere Damage

(language processing)

LEFT Hemisphere

language processing

speech production


Right Hemisphere



problem solving


(analyzing spoken language; comprehension)

Aphasia disorder – loss of ability to speak; caused by stroke / injury or tumor / infection

Split Brain Experiments

Mr. Split Brainy




Cerebrovascular Accident (CVA)

  • causes hemorrhage (rush of blood) or stroke (blood stops flowing through cerebral blood vessels)

  • victim can’t voluntarily move parts of the body on the side opposite to the side on which the accident occurred.


Concept Check #4

13.What is the protective covering of the brain and

spinal cord? What 3 layers make this covering up?

14. What is the brainstem responsible for and what

are its 3 parts?

15. What is the 2nd largest part of the brain and what

is it responsible for?

16. What is the largest part of the brain and what are

each of its lobes responsible for?

Concept Check #5

17.The ___________ separates the 2 hemispheres but they

connect at the ___________________.

18. How do hemorrhages and strokes differ?

19. What do each of the following cranial nerves control:

Optic? Olfactory? Glossopharyngeal? Vestibulocochlear??

Nervous System CSI #8 Questions….

1. Pesticides can affect the nervous system.

A) Explain how.

B) What symptoms did the uncle have that could indicate pesticides as the cause for his hospitalization).

2. Food-poisoning can affect the nervous system.

A) Explain how.

B) What symptoms did the uncle have that could indicate Botulism as the cause for his hospitalization).

3. Handling blue-algae can affect the nervous system.

A) Explain how.

B) What symptoms did the uncle have that could indicate blue-algae as the cause for his hospitalization).

Nervous System CSI #9 Questions….

  • List the problems this former football player was experiencing.

  • While he could be confused with having prion-related disorders

    or Alzheimer’s disease because of his symptoms, he is actually

    suffering from something else. What neurovascular condition is he

    suffering from? Explain what this condition is.

    3. What causes this condition? And, what was the football player

    doing to aggravate his condition?

    4. What can be done, if anything, to cure or reverse this condition?

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