The NERVOUS

SYSTEM

Central & Peripheral Nervous System

CSI #8 – Function of the 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.

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.

Central NS (CNS) Peripheral NS (PNS) brain & spinal cord stimulates muscles, emotions, thoughts, glands, and memories

nervous tissue OTHER THAN the brain & spinal cord

SENSORY function

(PNS to CNS)

transmits impulses

body brain/spinal cord

MOTOR function

(CNS to PNS)

transmits impulses

brain/spinal cord muscle

FUNCTIONS of the NERVOUS SYSTEM

1. Glia “glue” that holds neurons together

glioma – most common type of

brain tumor

Blood Brain Barrier –glia that separates blood & nervous tissue for protection

2 TYPES OF CELLS within the NERVOUS SYSTEM

2. Neurons (nerve cells) conduct and transmit impulses

Ex. sensory & motor neurons

(membrane that surrounds the entire nerve)

(membrane that surrounds each

fascicle)

Fascicle(bundle of axons)

Nerve Structure

(bundle of peripheral

axons)

(membrane that surrounds each axon)

cell body (contains nucleus)

dendrites(transmit impulses TO the cell body)

axon (transmit impulses AWAY

from the cell body)

STRUCTURE of a NEURON

direction of nerve impulse

(cells that produce myelin;

(white fatty substance that protects the axon)

(space betweenschwann cells)

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)

(receives impulses)(transmits impulses)

Conduction of Impulses

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

1. Resting

Neuron(maintaining an

excitable condition)

2. Impulse

Arrives

(cell has lost its

resting potential)

3. Impulse Passes

(Refractory period)

4. Reset

Na (+) charge

---------------

K (-) charge

(-) charge

---------------

Na and K (+) charge

K (+) charge

---------------

Na (-)Charge

Na (+) charge

--------------

K (-)Charge

It takes 0.001 seconds to reset a neuron; can carry 1000 impulses/sec.http://www.mind.ilstu.edu/curriculum/neurons_intro/flash_chemical.php?modGUI=232&compGUI=1827&itemGUI=3159

http://www.blackwellpublishing.com/matthews/actionp.html

a. conduction along unmyelinated fibers

b. conduction along myelinated fibers

Action Potential Animation:http://outreach.mcb.harvard.edu/animations/actionpotential.swf

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

http://www.youtube.com/watch?v=qgySDmRRzxY

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)

http://www.wnet.org/closetohome/animation/coca-anim-main.html

Have 2 different effects…1) Excitatory: a stimulus that encourages an A.P. 2) Inhibitory: a stimulus that discourages an A.P.

Neurotransmitters:

4-stage process when communicating with neurotransmitters:

1. Synthesis and storage of neurotransmitters (made in nerve cell body & stored in vesicles)

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

3. Neurotransmitter binding to post-synaptic receptors4. Inactivation of neurotransmitters (cell inactivates neurotransmitters by degrading them in synapse or re-uptake them for recycling.)

http://science.education.nih.gov/supplements/nih2/addiction/activities/lesson2_neurotransmission.htm

presynaptic neuron

postsynaptic neuron

http://www.mind.ilstu.edu/curriculum/neurons_intro/flash_chemical.php?modGUI=232&compGUI=1827&itemGUI=3159

Neurotransmitters:

Major Neurotransmitters in the Body

Neurotransmitter Role in the Body

Acetylcholine - used to control muscles and by many neurons in the brain to regulate memory.

- In most instances, acetylcholine is excitatory but can be inhibitory

Dopamine - Main focus neurotransmitter (no daydreaming) (inhbitory)

-produces feelings of pleasure when released by the brain reward system (excitatory)

GABA

(gamma-aminobutyric acid)

- acts like a brake to excitatory neurotransmitters that lead to anxiety (major inhibitory neurotransmitter in the brain)

Epinephrine - neurotransmitter /hormone; part of the flight-or-flight response and normal brain processes (excitatory)

Serotonin - neurotransmitter involved in many functions including mood, appetite, and sensory perception. (inhbitory)

Drugs Interfere with Neurotransmission

Change in

Neurotransmission

Effect on Neurotransmitter release or availability

Drug that acts this way

increase the # of impulses

increased neurotransmitter release

nicotine, http://www.thirteen.org/closetohome/home.html

alcohol, opiates

release neurotransmitter

from vesicles with or without impulses

increased neurotransmitter release

Amphetamines

(Adderall, Ritalin, ecstasy)

block reuptake more neurotransmitter present in synaptic cleft

cocaine

block receptor with

a

http://www.youtube.com/watch?v=of0TiyXWhOk

nother molecule

no change in amount of neurotransmitter released,

neurotransmitter cannot bind to receptor on postsynaptic

neuron

LSD

caffeine

http://www.youtube.com/watch?v=Tqwo9dmIXAQ

Effects of Alcohol on the Brainhttp://www.youtube.com/watch?v=of0TiyXWhOk

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

Threshold = 80 impulses / sec

Threshold Stimulus – the minimal stimulus requiredto evoke a response

A +50 imp

B - 50 impC -10 imp

All or None Response

D + 30 imp

cell body

learn something new – synapse forms forget something – synapse disappears

ExcitatoryE + 30 imp

A by itself = no transmission

A+D = transmission

A + B + D = no transmission

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

Concept Check #11. How do the Central NS & Peripheral NS differ?CNS includes brain and spinal cordPNS includes everything other than the brain & spinal cord.2. How do the sensory and motor neuron function in

the NS differ?Sensory – PNS to CNS Motor – CNS to PNS3. We know that the Blood Brain Barrier separatesblood and nervous tissue, but why is this important?-prevents harmful substances traveling through the bloodfrom entering the brain.4. Draw and label the structure of a neuron. Includethe dendrites, cell body, axon, nodes of ranvier andschwann cells.

Concept Check #25. What is believed to be the cause of myelindestruction in the auto-immune disease multiple sclerosis?bodies own immune-fighting cells (WBC) break thru theBBB and attack the myelin sheaths 6. How do pre & post synaptic neurons differ? Presynaptic – transmit Postsynapatic – receive7. Explain the direction in which nerve impulsestravel? (use the terms axon, dendrite, pre & post synaptic neurons)impulses travel from dendrite to axon of the presynaptic todendrites of postsynaptic?8. What is a nerve? What are the 3 layers of a nerveand how do they differ? Nerve – bundle of peripheral axons Epi – surrounds nerve; Peri – surrounds fascicleEndo – surrounds individual axons

Concept Check #39. What are neurotransmitters and how do theyfunction?chemicals that enable neurons to communicate;10. Name two excitatory NT and two inhibitory NT.Excitatory = acetylocholine, norepinephrine, glutamateInhibitory = Serotonin, GABA, glycine, endorphins, enke.

11. What is an action potential? Finish the diagrambelow. ++++ -+++ - - - - + - - - -nerve impulse at a specific point on a neuron’s axon + - ++ ++ -+ +++ - - + - - - - + - - - - +

Concept Check #412. How can drugs affect the way neurotransmitterswork? Can increase neurotransmitters or block reuptake ofneurotransmitters.

13. Explain how your brain can receive tons ofinformation but you only reacte or realize some ofthem? (be sure to use threshold stimulus and inhibitory impulses in your answer)

Inhibitory impulses block most impulses so they don’treach there threshold stimulus

The HUMANBRAIN

http://media.jeffersonhospital.org/videos/animation-meningitis?page=9&quicktabs_1=0

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

consists of midbrain, pons and medulla

Cerebellum 2nd largest part of the human brain

responsible for smooth coordinated movements, equilibrium, normal posture

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

The diencephalon (hypothalamus / thalamus) Hypothalamus controls all internal organs Thalamus regulates emotions

The Cerebrum largest and uppermost part of the brain

controls conscience thinking, memory, sensations, and emotions

4 Major Lobes of the Human Brain

http://www.physpharm.fmd.uwo.ca/undergrad/sensesweb/L12Memory/L12Memory.swf

cerebral cortex:(surface of cerebrum)

Parts of the Cerebrum

(ridges of cortex))

(grooves of cortex)

lateral fissure:deepest groove of the brainthat separates thebrain into 2 hemispheres

Corpus

Callosum

• connects the

hemispheres at

the lowest

point

http://viewzone2.com/bicamx.htmlLeft Brain vs. Right Brain

LEFT BRAIN FUNCTIONS 

uses logicdetail oriented

facts rulewords and language

present and pastmath and sciencecan comprehend

knowingacknowledges

order/pattern perceptionknows object name

reality basedforms strategies

practicalsafe

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

LEFT Hemispherelanguage processingspeech production

comprehension

Left vs. Right Hemisphere Damage

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

(analyzing spoken language; comprehension)

Right Hemispherememory

organizationproblem solving

reasoning

http://www.dailytelegraph.com.au/news/wacky/the-right-brain-vs-left-brain/story-e6frev20-1111114577583

(language processing)

Mr. Split Brainyhttp://www.nobelprize.org/educational/medicine/split-brain/splitBrain_main.swf

Split Brain Experiments

1. http://brain.web-us.com/brain/right_left_brain_characteristics.htm2. http://brain.w-us.com/brain/braindominance.htm3. http://www.angelfire.com/wi/2brains/test.html

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.

12 PAIRS of CRANIAL NERVES

http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP11504

Concept Check #413. What is the protective covering of the brain andspinal cord? What 3 layers make this covering up?meninges dura mater, arachnoid, pia mater14. What is the brainstem responsible for and whatare its 3 parts?Vitals heart rate, respiration, blood vessel diameterMidbrain, pons, medulla15. What is the 2nd largest part of the brain and whatis it responsible for?cerebellum smooth movements, equilibrium, posture16. What is the largest part of the brain and what areeach of its lobes responsible for?Cerebrum frontal (decision making) parietal (reception, processing info) occipital (vision) temporal (hearing, emotion, language)

Concept Check #517. The ___________ separates the 2 hemispheres but theyconnect at the ___________________.lateral fissure and corpus callosum18. How do the left and right brain dominant peoplediffer?Left – language, reality, facts Right – reasoning, memory

19. How do hemorrhages and strokes differ?hemorrhage: rush of blood stroke – blood flow stops

20. What do each of the following cranial nerves control:Optic? Olfactory? Glossopharyngeal? Vestibulocochlear??Eye Nose Tongue Ear