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Phgy 455 > WEEK 2- MS pt 2 > Flashcards

WEEK 2- MS pt 2 Flashcards

1
Q

true or false Nerve fibres and cell bodies outside the CNS are part of the CNS

A

false PNS

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2
Q

what structire connects CNS to PNS

A

nerves

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3
Q

PNS is involved with long or short distance transmission

A

long

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4
Q

at rest neurons have a positive or negative charge

A

negative

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5
Q

make sure you understand sodium channels during ap slide 5

A

!

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6
Q

what is a refractory period

A

period where action potential is not possible. Prevents
backwards propagation.

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7
Q

what are two ways you can increase conduction velocity of neurons

A

○ Increasing diameter
of Axon

○ Insulate Axon - Myelination

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8
Q

what is myelin

A

multiple layers of close glial membranes

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9
Q

which glial cell makes up myelin in the PNS

A

schwaan

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10
Q

true or false: all axons are covered with teh same maount of myelin

A

false, Different axons are covered with different number of layers of Schwann cell membranes

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11
Q

true or false an unmyelamted axon sends a message must faster than a myelnated one

A

false
The action potential in an unmyelinated axon depolarizes all of the membrane and so consumes more energy, much slower transmission.

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12
Q

what helps with the speed of the signal in a myelnated axon

A

the nodes of ranvier = signal jumps from one gap to the next

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13
Q

what is a node de ranvier

A

Gap in myelin which allows charge to enter/leave nerve cell to generate AP

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14
Q

t or F nodes of ranvier do not contain ion channels

A

f they do

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15
Q

how far apart are nodes of ranvier in an axon

A

1-2 mm

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16
Q

what are two condiitons that involve damage to myelin sheath

A

multiple sclerosis
guillian barre syndrome

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17
Q

briefly describe multiple sclerosis and
guillian barre syndrome

A

Auto-immune diseases that cause damage to the myelin sheath and eventual axon loss

18
Q

in multiple sclerosis and
guillian barre syndrome the nerve conduction is ….

A

Slowed down

19
Q

in multiple sclerosis and
guillian barre syndrome causes

A

gradual weakness, paralysis and sensory loss

20
Q

true or false peripheral nerves are only made uo of sensory nerves

A

false , motor also

21
Q

what are the two types of peripheral nerve injury

A

axon cut
axon crush

22
Q

which of the two (axon cut vs crush) is faster regenration

A

crush

23
Q

axon cut can cause something called distal axon segment degenretaion… explain

A

○ Occurs within 24 hours of cut
○ Axonal degeneration is followed by degradation of the myelin sheath and infiltration by
macrophages. The macrophages, aided by Schwann cells clear the debris.
○ The outer myelin sheath (neurilemma tube) does not degenerate and remains as a hollow
tube.

24
Q

what is one way to speed up recovery of axon cut

A

Surgical reattachment of distal segment speeds up recovery

25
Q

why is axon crush faster at regenertaing than axon cut

A

full degeneration of distal segment does not occur

26
Q

true or false in axon cut the proximal end (closest to injury) is the part of axon taht degenerates

A

faslse = the distal

27
Q

what happens as a step of peripheral nerve regenration

A

axonal sprouting

28
Q

how much time does it take for sprouting to occur

A

96 hours

29
Q

what are sprouts called at proximal end of axon

A

neurites

30
Q

when does a neurite grow into the neurilemma tube

A

If a sprout reaches the neurilemma tube, it grows into it and advances about 1-3 mm per day.

31
Q

what are neurites attracted by

A

growth factors by shwaan cells

32
Q

t or f regeneration is always complete explain

A

false = axons can split into many paths

33
Q

what happens if the sprouts cannot reach the neurilemma tube

A

they may form a neuroma,
or grow into other tissues.

34
Q

true or false Axons must grow distances much greater than they did during development
in the embryo in the regenrtaion process

A

true

35
Q

t or false the cns is always intact when there are changed in peripheral nerve injuries

A

false

36
Q

do Axons regenerate along Schwann cell paths and stay in only one path?

A

no, they do not stay in one path
They can branch out and go down in a random manner

37
Q

surgical reattachment use what?

A

sutures

38
Q

what 3 things can compromosie the results of surgical nerve repair

A

Tension, scar formation and missing
nerve tissue

39
Q

t or f after a 45 min surgery, the nerve is good as new

A

false : The technique takes many hours and
often does not line up perfectly

40
Q

true or false the branching out of axons after surgical intervention is much more controlled vs non surgical reattachment

A

true

41
Q

how can oT and PT help

A

● Sensory desensitization and re-education

● Relearning movement and sensation to help strengthen new patterns of
signals in the brain

Phgy 455 (19 decks)

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