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13 Cards in this Set
- Front
- Back
- 3rd side (hint)
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The main components of the peripheral nervous system are the
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Nerves
Ganglia Nerve endings (to be studied in integumentary system) |
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Coverings of Axon
CNS |
Unmyelinated
No sheath (lie in between glial cells) |
Sheath of myelin
(Oligodendrocytes) |
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Coverings of Axon
PNS |
Unmyelinated
Sheath of Schwann (e.g. fine sensory fibers, postganglionic fibers of autonomic nerve, axons of olfactory nerve) |
Myelinated
Sheath of Myelin + Sheath of Schwann |
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Schwann cells have a __________?
nucleus |
heterochromatic
info |
Schwann cells have a heterochromatic nucleus, numerous mitochondria, microtubules, microfilaments, lysosomes, RER and Golgi apparatus
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Schwann cells envelope all nerve fibers of
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PNS
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Myelin in axons of the PNS is derived from cells called
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Schwann cells (or neurilemmal cells).
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Myelin Dz
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Cystic fibrosis
Charcot Marie Tooth |
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***
Protein zero and PMP22 are the proteins of ____? Proteolipid protein (PLP) is found only in _____? |
PNS myelin
CNS myelin |
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Myelination
***There are no Schwann cells in the ____? |
CNS
Instead neuroglial cells called oligodendrocyte form myelin. One cells can form myelin sheaths around several axons. Unmyelinated axons in PNS do not have the characteristic winding around of myelin in many layers, the axons lie embedded in Schwann cell cytoplasm. |
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Myelination
does what for the Nervous system = 3ct |
Insulation
The thicker the myelin sheath the faster the speed of conduction Conserves energy |
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Velocity of conduction of the nerve impulse is directly related to :
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. The thickness of the myelin sheath
2. The diameter of the nerve fiber i.e. the thicker the myelin sheath and the wider the diameter, the faster is the speed of conduction. |
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***
Demyelination Dz are: 3 separate catagories with subcatagories. |
IMMUNE MEDIATED
-multiple sclerosis, -Guillain-Barre syndrome INHERITED: -Adrenoleukodystrophy METABOLIC: -Central Pontine Myelinosis, -Vtamin B 12 Deficiency virus induced: progressive multifocal encephalopathy |
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The loss of myelin causes loss of insulation in nerve fibers and this results in much less efficient nerve conduction.
3ct area of nerve system: |
Sensory =
Motor = ANS (Autonomic Nervous System) = |
Sensory:
disturbances in special senses e.g. vision (double vision and partial blindness). General- paraesthesia and numbness e.g. in upper limb or face Motor: Weakness of muscles in a whole limb (called monoplegia) or in half of the body (called hemiplegia). Muscle tremor (= shaking) Autonomic system: sphincter dysfunction causing incontinence impotence |
