WEEK 2- MS pt 2

Question 1

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

Answer 1

false PNS

Question 2

what structire connects CNS to PNS

Answer 2

nerves

Question 3

PNS is involved with long or short distance transmission

Answer 3

long

Question 4

at rest neurons have a positive or negative charge

Answer 4

negative

Question 5

make sure you understand sodium channels during ap slide 5

Answer 5

!

Question 6

what is a refractory period

Answer 6

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

Question 7

what are two ways you can increase conduction velocity of neurons

Answer 7

○ Increasing diameter
of Axon

○ Insulate Axon - Myelination

Question 8

what is myelin

Answer 8

multiple layers of close glial membranes

Question 9

which glial cell makes up myelin in the PNS

Answer 9

schwaan

Question 10

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

Answer 10

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

Question 11

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

Answer 11

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

Question 12

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

Answer 12

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

Question 13

what is a node de ranvier

Answer 13

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

Question 14

t or F nodes of ranvier do not contain ion channels

Answer 14

f they do

Question 15

how far apart are nodes of ranvier in an axon

Answer 15

1-2 mm

Question 16

what are two condiitons that involve damage to myelin sheath

Answer 16

multiple sclerosis
guillian barre syndrome

Question 17

briefly describe multiple sclerosis and
guillian barre syndrome

Answer 17

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

Question 18

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

Answer 18

Slowed down

Question 19

in multiple sclerosis and
guillian barre syndrome causes

Answer 19

gradual weakness, paralysis and sensory loss

Question 20

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

Answer 20

false , motor also

Question 21

what are the two types of peripheral nerve injury

Answer 21

axon cut
axon crush

Question 22

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

Answer 22

crush

Question 23

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

Answer 23

○ 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.

Question 24

what is one way to speed up recovery of axon cut

Answer 24

Surgical reattachment of distal segment speeds up recovery

Question 25

why is axon crush faster at regenertaing than axon cut

Answer 25

full degeneration of distal segment does not occur

Question 26

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

Answer 26

faslse = the distal

Question 27

what happens as a step of peripheral nerve regenration

Answer 27

axonal sprouting

Question 28

how much time does it take for sprouting to occur

Answer 28

96 hours

Question 29

what are sprouts called at proximal end of axon

Answer 29

neurites

Question 30

when does a neurite grow into the neurilemma tube

Answer 30

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

Question 31

what are neurites attracted by

Answer 31

growth factors by shwaan cells

Question 32

t or f regeneration is always complete explain

Answer 32

false = axons can split into many paths

Question 33

what happens if the sprouts cannot reach the neurilemma tube

Answer 33

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

Question 34

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

Answer 34

true

Question 35

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

Answer 35

false

Question 36

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

Answer 36

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

Question 37

surgical reattachment use what?

Answer 37

sutures

Question 38

what 3 things can compromosie the results of surgical nerve repair

Answer 38

Tension, scar formation and missing nerve tissue

Question 39

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

Answer 39

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

Question 40

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

Answer 40

true

Question 41

how can oT and PT help

Answer 41

● Sensory desensitization and re-education ● Relearning movement and sensation to help strengthen new patterns of signals in the brain