Transcript The Nervous System

The Nervous System
I. General organization of nervous system
A. CNS
1. brain
2. spinal cord
B. PNS
1. sensory
2. motor
a. Somatic
b. ANS
-sympathetic
-parasympathetic
II. Nervous Supporting Cells - neuroglia
A. Astrocytes
1.
2.
Connect to
capillaries
Mopping up
chemical
environment of
brain as far as
potassium ions and
neurotransmitters
B. Microglia
• 1. spider-like
phagocytes
• 2. debris, dead
brain cells, bacteria
C. Ependymal cells
• 1. lines cavities in CNS
• 2. beating of cilia moves
cerebrospinal fluid
• 3. fluid nourishes and cushions
CNS
D. Oligodendrocytes
• 1. wrap axons of nerve cells
with fatty layer
• 2. produces myelin sheath
• 3. speeds conduction
E. Glia cells in general
•
•
•
•
•
1.
2.
3.
4.
5.
resemble neurons
not excitable
supportive cells
capable of repeated mitosis
gliomas-glial tumors
III. Neurons
A. Structure
•
•
•
•
•
•
•
•
•
1.
2.
3.
4.
5.
6.
7.
8.
9.
cell body
nissl bodies-rer
dendrites
axon
axon hillock
axon collateral
axon terminals
neurotransmitters
synaptic cleft
B. Myelin sheath
•
•
•
•
1. functions
2. PNS-Schwann cell
3. Node of Ranvier
4. Can form a pathway for
regrowth of damaged
axon
• 5. multiple sclerosis
C. Neurons classified by function
•
•
•
•
•
1.
2.
3.
4.
5.
afferent
interneuron
efferent
ganglia
nuclei
D. Neurons classified by structure
• 1. multipolar
• 2. bipolar
• 3. unipolar
IV. Neuron physiology
• A. Resting membrane
potential
• B. Action potential-nerve
impulse
C. Propagation of action potential
• 1. diagram on board
• 2. a lot like dominoes
• 3. http://www.youtube.com/watch?v=7tBWl4GE8rk&NR=1
D. Anatomy of a synapse
•
•
•
•
•
1. presynaptic membrane
2. synaptic cleft
3. postsynaptic membrane
4. synaptic vesicles
5. receptor sites for transmitter
substance
E. Physiology of synapse
• 1. action potential arrives
• 2. Calcium ion channels
open
• 3. synaptic vesicles fuse
with membrane
• 4. transmitter substance
released
• 5. diffusion of transmitter
substance
• 6. binding to receptors
• 7. creates a graded
potential
• 8. may bring postsynaptic
membrane to threshold
• 9. nerve gas-blocks
cholinesterase
F. You tube of synaptic events
• http://www.youtube.com/watch?v=z3F5dfmQ
3hk
V. Functional Anatomy of the Brain
A. Introduction
•
•
•
•
1. difficult to talk about
2. two fistfuls of pinkish/gray
3. wrinkled
4. consistency of cold
oatmeal
• 5. three pounds
• 6. hugely complex
• 7. four basic regions
–
–
–
–
a.
b.
c.
d.
Cerebral hemispheres
Diencephalon
Brain stem
cerebellum
B. Cerebral hemispheres
• 1. most important part
• 2. overshadows
diencephalon and brain
stem
• 3. mushroom cap covers
top of stalk
• 4. gyri
• 5. sulci
• 6. fissures-ie longitudinal
cerebral fissure
7. Lobes of cerebrum
• a. Frontal lobe
controls mainly motor
function
• b. Primary motor area
is on the precentral
gyrus -governs
conscious motor
control which can be
mapped
Motor homunculus
c. Motor homunculus
• -specific regions of
the precentral
gyrus control
specific body parts
• -finer the
movements, the
more brain area
needed to control
those movements
d. Premotor area
• -learned
repetitive
tasks
• Typing,
playing piano
• Athletes
learn tasks
by visualizing
motions
• Ingrained in
this area
e. Broca’s area
• speech center
• Usually located left cerebral hemisphere
• Damage here causes inability to speak
8. Other important areas of cerebral hemispheres
•
•
•
•
•
a. Primary somatic sensory area
b. Visual area in occipital lobe
c. Complex memory in the temporal lobe
d. Note close proximity to olfactory area
e. Anterior association area-higher intellectual reasoning and
socially acceptable behavior
9. Sensory homunculus
C. Diencephalon
1. Thalamus
a. Encloses third vent.
b. Screens incoming
sensory messages
2. Hypothalamus
a. ANS center for body
temperature and water
balance
b. Regulates pituitary
3. Epithalamus
a. Pineal gland
b. Choroid plexus
D. Brain stem
•
•
•
•
•
1. size of thumb
2. midbrain
3. pons
4. medulla
5. interchange
for sensory and
motor paths
• 6. nuclei for
respiratory,
blood pressure,
heart rate, RAS
E. Cerebellum
1. Cauliflower
shape
2. Controls
balance and
equilibrium
3. Produces
smooth and
coordinated
muscular
contractions
VI. Protection of the
brain
•
•
•
•
•
•
A. Meninges
1. dura mater
2. arachnoid
3. pia mater
B. CSF
1. produced
choroid plexi
• 2. flow
• 3. functions
• 4. hydrocephalus