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Notes - The Nervous System Overview
Organization & Overview of the Nervous System pages 388-397
I. List the 3 overlapping functions of NS
A. Sensory input:
B. Integration:
C. Motor output:
II. Nervous Tissue Anatomy
A. Neuroglia are the “____________________” and generally
________________________, _______________________, &
_____________________ the neurons. They can __________________________ but
cannot __________________________.
a. See figure 7.3 page 205 – need to understand the different roles these cells have
but do not need to memorize.
B. Neurons can ___________________ but cannot ___________________
a. special characteristics
i. longevity
ii. amitotic ( there are some exceptions)
iii. high metabolic rate
iv. Brain Tumors:
b. Why is the plasma membrane of a neuron so important?
c. Anatomy of a Neuron – Need to memorize diagram
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i. Cell body is the ___________________________center of the neuron. It
contains most organelles with the exception of _________________ which
means the neuron cannot replicate through mitosis.
ii. Processes & Covering
1. Dendrites
a. hundreds of short, thick, diffusely branched, close to cell body
b. _________ sites; transmit impulses _______ cell body
2. Axons
a. transmit impulses _______ from cell body
b. varies in length and diameter (larger diameter=faster
conduction)
c. axon collaterals: ___________________________________
d. axon terminals located _______________________________
i. contain _____________________________,
chemicals which transmit the impulse electrically from
one nerve to the next or to the end target
ii. Separated from next neuron (or organ or muscle) by
the __________________________________.
The entire junction between 2 nerves or a nerve and
another structure is known as the _________________
3. Myelin sheath: see fig 7.5 page 208 – ___________________ &
__________________ the fibers and __________________ the
speed of transmission
d. Classification of Neurons
i. Functional classification
1. sensory (afferent)
a. carry impulses from _______________ to ______
b. Ends of dendrites are associated with specialized receptors
i. Cutaneous receptors: pressure, pain, heat, cold
ii. Proprioceptors: muscles & tendons: amount of stretch
or tension
iii. Specialized receptors in sense organs: sight, hearing,
smell, taste, equilibrium
2. motor (efferent)
a. carry impulses from _______ to ______________________
3. association (interneurons)
a. responsible for integration & reflex – connect motor and
sensory neurons
b. ________ of neurons
End of Quiz #1 Material – all matching
III.
Nervous Tissue Physiology - Two major functional properties of neurons resulting in
electrochemical event
A. Irritability:
a. Define: ________________________________________________________
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B. Conductivity: Memorize synaptic cleft diagram
a. Define: _______________________________________________________
b. Stages of _______________________ event:
i. Action potential (electrical signal reaches axon ______________________
ii. Vesicle fuses with membrane and ruptures releasing
________________________ into synaptic cleft
iii. NT (chemical signal) diffuses across cleft and binds to
______________________
iv. Action potential (electrical signal) begins on ______________ neuron (or
muscle or gland)
v. NT quickly removed from synapse by _________________________ or
_____________________________________
c. As you learn:
i. Axon terminals widen so more NT can be released (more surface area)
ii. Synaptic cleft narrows
iii. More NT gets across to receptor
iv. Faster more efficient process
C. Reflex Arc: Memorize diagram
a. A reflex is a ___________________________________________________
response to stimuli that the body is programmed to do
b. Differentiate between an autonomic reflex and a somatic reflex and give an
example of each.
i. Autonomic
ii. Somatic
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IV.
Regeneration:
A. Introduction
i. mature neurons incapable of cell division
ii. ________ nerve axons can regenerate successfully if cell body is not
destroyed
iii. Uninjured cell body swells to prepare to synthesize proteins to support
regeneration
1. axon regeneration = ______________________
2. greater distance = less recovery chance = possible ______________
formation
3. Retraining of nerve necessary
B. PNS axons - in certain cases
i. debris cleaned out by macrophages
1. Schwann cells form tunnel of __________________________ to
guide regenerating axonal "sprouts"
2. Schwann cells release growth factor
C. CNS - does not happen - WHY??
End of Quiz #2 Material
Classification & divisions of the NS
Construct a flow chart on the last page of these notes. You will need to know each division and
the 2 pieces of info under each one. This will be a matching section. (on test – not on quiz)
Central Nervous System
I.
Protections of the Brain & Spinal cord
A. scalp & hair: ______________________________
B. bone: ____________________________________
C. meninges – see page 463-465
i. epidural space: _________________________
ii. dura mater - contain dural sinuses – collect venous blood & shunt to internal
jugular vein
iii. subdural space: _________________________
iv. arachnoid______________________________
v. subarachnoid space: _____________________
vi. pia mater:_____________________________
D. blood - brain barrier
i. Function: ensures stable environment by endothelial tight junctions in blood
capillaries
ii. excludes some substances while allowing other substances to freely pass :
List those that can pass through __________________________________
_____________________________________________________________
iii. not identical in all regions - ex. hypothalamus almost non-existent to sample
comp. of blood
iv. BBB is incomplete in newborns: May lead to kernicturus
______________________________________________________________
_____________________________________________________
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II.
CSF
A.
functions
i.
support, protect, & exchange of materials
ii.
forms a cushion
iii.
circulating fluid to monitor levels of _____, _____, & ____ to trigger
feedback mechanisms if necessary to maintain homeostasis
B. location: subarachnoid space & 4 ventricles in brain & central canal
C. ~800 ml formed daily in the choroid plexus seeps from the capillaries and into
ventricles
D. circulation pattern
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
E. hydrocephalus - newborn vs. adult - see imbalance pg 465-467
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BRAIN ANATOMY (page 434-453)
Brain & spinal cord develops from neural tube
4 major regions: cerebral hemispheres, diencephalon, brain stem, and cerebellum
I.
Cerebral hemispheres (Cerebrum)
A.
surface
i.
gyri: ________________________________________
ii.
sulci: ________________________________________
a)
Purpose: ____________________________________
b)
fissures: _____________________________________
(1)
longitudinal fissure: _________________________
(2)
transverse fissure: __________________________
(3)
lateral fissure: ______________________________
iii.
Lobes – named for bones they lie under
B.
divisions
i.
Cerebrum
a)
cerebral cortex
(1)
gray matter = cell_____________
(a)
thickness: ___________, _______% of brain mass
(b)
Function: voluntary motion, higher order thinking skills
(2)
Cerebral White Matter
(a)
corpus callosum - largest fiber tract connecting the
two hemispheres – if cut, left & right brain cannot
communicate
(b)
basal nuclei – located deep within the white matter islands of gray matter
(i)
indirectly help initiate and control slow,
stereotyped muscle movement
(ii)
ex. arm swinging while walking
ii.
Diencephalon
a)
located on _________________________
b)
enclosed by cerebral hemispheres
c)
Made of 3 parts:
(1)
________________________________________________
(2)
_______________________________________________
(3)
________________________________________________
iii.
Brain Stem
a)
attaches to spinal cord
b)
Controls the rigidly programmed automatic behaviors necessary for
__________________________________________
c)
iv.
Has 3 parts:
(1)
________________________________________________
(2)
_______________________________________________
(3)
________________________________________________
Cerebellum
a)
Function – produce smooth, coordinated motions
b)
Damage results in ataxia: uncoordinated wavering motions
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Complete the Brain Study Diagram at the back of these notes & study it.
End of Quiz #3 Material – does not include info
from function charts & WS
Developmental Aspects of the CNS (pages 481-485)
1. Cerebral palsy
2. Alzheimer’s disease
3. Parkinson’s disease
4. Huntington’s disease (chorea)
Make sure you know the following Brain disorders
1. meningitis
2. encephalitis
3. cerebral edema
8. CVA
9. ischemia
10. TIA
12. multiple sclerosis
13. hemiplegia
Spinal Cord Anatomy (page 226 in text)
See nerve structure diagram
I. Approximately ___________ long and extends from _________________________
to _________________________________ and is about the size of your
______________ for most of its length.
II. Meningeal coverings extend to the level of___________________________ (see
picture)
III. See nerve plexus diagram
IV. See Dermatome diagram.
V. What is the purpose of a lumbar (or spinal) tap? Why is this procedure done at the
level of L4 or L5? Why must the patient remain lying down for 6-12 hours after this
procedure (be specific as to why)?
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VI. Define the following:
1. Flaccid paralysis
2. Spastic paralysis
3. Quadriplegic
4. Paraplegic
5. Spina bifida-incomplete formation of vertebrae – folic acid reduces risk
1. Occulta-no external manifestations
2. Cystica-saclike cyst protrudes from spine
3. Meningocele-cyst contains meninges & CSF
4. Myelomeningocele-cyst also contains portions of spinal cord and nerve
roots
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Nerve structure
Nerve Plexus
Dermatomes:
These diagrams show
you the area of skin
supplied by the root of
each spinal nerve.
Pain in these skin
areas can tell you
about organ damage
going on. For
example: Damage to
the sciatic nerve will
manifest itself as pain
in the S2 area of your
leg since the sciatic
nerve comes out of the
sacral vertebrae.
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