Transcript NERVOUS SYSTEM CNS-Central Nervous System PNS

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 emergencyroom 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 nervous tissue OTHER
 stimulates muscles, THAN the brain & spinal
cord
emotions, thoughts,
glands, and memories
FUNCTIONS of the NERVOUS SYSTEM
SENSORY function
(PNS to CNS)
MOTOR function
(CNS to PNS)
 transmits impulses
body  brain/spinal cord
 transmits impulses
brain/spinal cord  muscle
2 TYPES OF CELLS within 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. Neurons (nerve cells)
 conduct and transmit impulses
Ex. sensory & motor
neurons
Nerve Structure
(bundle of
peripheral
axons)
(membrane that
surrounds each
fascicle)
(membrane that
surrounds the entire
nerve)
Fascicle
(bundle of axons)
(membrane that
surrounds each axon)
dendrites
STRUCTURE of a NEURON
(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
(space btwn neurons
neurilemma so regeneration
is are
much
less
were impulses
transmitted)
than it is in the PNS.
Conduction of Impulses
 action potential: a nerve impulse at a given point on an
axon (neuron)
1.
Resting
Neuron
2.
3. Impulse Passes
(Refractory period)
4. Reset
(maintaining an
excitable condition)
Impulse
Arrives
(cell has lost its
resting potential)
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
Action Potential Animation:
http://outreach.mcb.harvard.edu/animations/actionpotential.swf
http://www.blackwellpublishing.com/matthews/actionp.html
a. conduction along unmyelinated
fibers
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
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
Neurotransmitters:
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:
1. Synthesis and storage of neurotransmitters
(made in nerve cell body & stored in vesicles) http://science.educatio
2. Neurotransmitter release
nts/nih2/addiction/activ
transmission.htm
(influx of Ca during A.P. causes neurotransmitter release)
3. Neurotransmitter binding to post-synaptic receptors
4. Inactivation of neurotransmitters
(cell inactivates neurotransmitters by degrading them in synapse
or re-uptake them for recycling.)
presynaptic neuron
Neurotransmitters:
http://www.mind.ilstu.edu/curriculum/neurons
_intro/flash_chemical.php?modGUI=232&com
pGUI=1827&itemGUI=3159
postsynaptic neuron
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
- acts like a brake to excitatory neurotransmitters that lead
to anxiety (major inhibitory neurotransmitter in the
(gammabrain)
aminobutyric acid)
Epinephrine
Serotonin
- neurotransmitter /hormone; part of the flight-or-flight
response and normal brain processes (excitatory)
- neurotransmitter involved in many functions including
mood, appetite, and sensory perception. (inhbitory)
Drugs Interfere with Neurotransmission
Change in
Effect on Neurotransmitter Drug that acts
release or availability
this way
Neurotransmission
increase the # of
increased neurotransmitter
nicotine,
impulses
release
alcohol,
opiates
release
increased neurotransmitter Amphetamines
neurotransmitter
release
(Adderall,
from vesicles with or
Ritalin, ecstasy)
without impulses
block reuptake
more neurotransmitter
cocaine
present in synaptic cleft
block receptor with
no change in amount of
LSD
neurotransmitter released,
a
caffeine
http://www.youtub neurotransmitter cannot bind
http://www.thirteen.org/closetohome/hom
e.html
http://www.youtube.com/watch?v=Tqwo9dm
Effects of Alcohol on the Brain
http://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
Clear your impulses.
Minds
inhibitory
Threshold Stimulus – the minimal stimulus required
to evoke a response
 All or None Response
B - 50 imp
C -10 imp
A +50 imp
D + 30 imp
cell body
Excitatory
E + 30 imp
Threshold = 80 impulses / sec
A by itself = no transmission
A+D = transmission
A + B + D = no transmission
 learn something new – synapse forms
 forget something – synapse disappears
 endorphins are released
by neurons in brain to
inhibit pain/fear; reason we
can calm ourselves down?
Concept Check #1
1.
How do the Central NS & Peripheral NS differ?
CNS includes brain and spinal cord
PNS 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 PNS
3. We know that the Blood Brain Barrier separates
blood and nervous tissue, but why is this important?
-prevents harmful substances traveling through the blood
from entering the brain.
4. Draw and label the structure of a neuron. Include
the dendrites, cell body, axon, nodes of ranvier and
schwann cells.
Concept Check #2
5. What is believed to be the cause of myelin
destruction in the auto-immune disease multiple sclerosis?
bodies own immune-fighting cells (WBC) break thru the
BBB and attack the myelin sheaths
6. How do pre & post synaptic neurons differ?
Presynaptic – transmit
Postsynapatic – receive
7. Explain the direction in which nerve impulses
travel? (use the terms axon, dendrite, pre & post synaptic neurons)
impulses travel from dendrite to axon of the presynaptic to
dendrites of postsynaptic?
8. What is a nerve? What are the 3 layers of a nerve
and how do they differ?
Nerve – bundle of peripheral axons
Epi – surrounds nerve; Peri – surrounds fascicle
Endo – surrounds individual axons
Concept Check #3
9. What are neurotransmitters and how do they
function?
chemicals that enable neurons to communicate;
10. Name two excitatory NT and two inhibitory NT.
Excitatory = acetylocholine, norepinephrine, glutamate
Inhibitory = Serotonin, GABA, glycine, endorphins, enke.
11. What is an action potential? Finish the diagram
below. ++++ -+++ 
---- +--- 
-nerve impulse at a specific point on a neuron’s axon
+ - ++ ++ -+ +++ -+-- --+- ---+
Concept Check #4
12. How can drugs affect the way neurotransmitters
work?
Can increase neurotransmitters or block reuptake of
neurotransmitters.
13. 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)
Inhibitory impulses block most impulses so they don’t
reach there threshold stimulus
The
HUMAN
BRAIN
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
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
http://www.physpharm.fmd.uwo.ca/undergrad/sensesweb/L12Memory/L12Memory.swf
Parts of the Cerebrum
cerebral cortex:
(surface of cerebrum)
(ridges of cortex))
(grooves of cortex)
lateral
fissure:
deepest groove
of the brain
that separates the
brain into 2
hemispheres
Corpus • connects the
Callosum
hemispheres at
the lowest
point
Left Brain vs. Right Brain
http://viewzone2.com/bicamx.html
LEFT BRAIN FUNCTIONS RIGHT BRAIN FUNCTIONS
uses logic
detail oriented
facts rule
words and language
present and past
math and science
can comprehend
knowing
acknowledges
order/pattern perception
knows object name
reality based
forms strategies
practical
safe
uses feeling
"big picture" oriented
imagination rules
symbols and images
present and future
philosophy & religion
can "get it" (i.e. meaning)
believes
appreciates
spatial perception
knows object function
fantasy based
presents possibilities
impetuous
risk taking
Left vs. Right Hemisphere Damage
(language processing)
LEFT Hemisphere
language processing
speech production
comprehension
(analyzing spoken language;
comprehension)
Aphasia disorder – loss of ability to speak;
caused by stroke / injury or tumor / infection
Right Hemisphere
memory
organization
problem solving
reasoning
http://www.dailytelegraph.com.au/news/wac
ky/the-right-brain-vs-left-brain/storye6frev20-1111114577583
Split Brain Experiments
Mr. Split Brainy
http://www.nobelprize.org/educational/medicine/split-brain/splitBrain_
1. http://brain.webus.com/brain/right_left_brain_characteristics.htm
2. http://brain.w-us.com/brain/braindominance.htm
3. 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
Concept Check #4
13. What is the protective covering of the brain and
spinal cord? What 3 layers make this covering up?
meninges  dura mater, arachnoid, pia mater
14. What is the brainstem responsible for and what
are its 3 parts?
Vitals  heart rate, respiration, blood vessel diameter
Midbrain, pons, medulla
15. What is the 2nd largest part of the brain and what
is it responsible for?
cerebellum  smooth movements, equilibrium, posture
16. What is the largest part of the brain and what are
each of its lobes responsible for?
Cerebrum  frontal (decision making)
parietal (reception, processing info)
occipital (vision)
temporal (hearing, emotion, language)
Concept Check #5
17. The ___________ separates the 2 hemispheres but they
connect at the ___________________.
lateral fissure and corpus callosum
18. How do the left and right brain dominant people
differ?
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