Neuroregeneration Lec24 Flashcards Preview

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Flashcards in Neuroregeneration Lec24 Deck (36):
1

Nerves can sometimes regenerate in the ___

PNS

2

Nerves can almost never regenerate in the ___

CNS

3

Effective nerve regeneration requires: (4)

1. survival of the nerve cell body (damage to axon only) 2. clearance of the damaged distal axon, myelin breakdown products, and other debris 3. a supportive environment that stimulates new axonal regrowth (limited inflammation) 4. guidance cues for the axon to find its original cellular target

4

after injury CNS Wallerian degeneration is ___ and ___

slow and incomplete

5

what is one reason why the CNS is a hostile environment for tissue regeneration? *

1. oligodendrocytes don't help clean up debris so myelin persists in the CNS

2.  CNS neurons result in a glial scar (purpose was to limit tissue damage -- but now serve as a barrier)

6

in PNS injury Denervated myelinating Schwann cells release their myelin and ___

proliferate, produce trophic factors, and phagocytose debris (~24 hours)

7

After a nerve injury in the CNS and PNS, Wallerian degeneration occurs where the axon that is cut off is ___ and ____

degenerated and its myelin sheath degraded

8

After nerve injury ___ and ___ are recruited work to clear away the debris.

schwann cells and macrophages

9

after pns injury The macrophages produce factors that facilitate ___ and ___

Schwann cell migration & axon regeneration

10

Injured axons form a growth cone and regenerate along the ___ formed by Schwann cells

bands of Bungner

11

bands of Bungner guide the___ to their targets

growth cones

12

Schwann cells that are chronically denervated for a few months are less supportive of regrowth and more likely to ____

apoptose

13

If the axon can traverse the injury site, it may reconnect successfully. this typically takses

months to years

14

compared to the original, the regenerated axon will have

thinner myelin and shorter nodal length

15

why are come compression injuries easier to repair?

some axons may be spared - easier to repair.

16

____ of muscles following peripheral motor nerve damage is precise - almost exactly the same as before injury

Reinnervation

17

what does the CNS lack that may it ineffective at repair? (3)

1. clearence of debris

2. a supportive environment

3. guidance cues

18

Wallerian Degeneration:
- acute axon degeneration is mediated by __ and ___

Ca influx and activation of calpain

19

  For___ hours after injury, the distal (disconnected) axon remains stable.

 24-48

20

Full fragmentation and breakdown of the distal axon occurs ~___ hours after injury,

72

21

after full fragmentation and breakdown of the distal axon, ___ occurs

increased glial support (astrocytes and macrophages) to clear debris

22

 in PNS, Schwann cells shed myelin and ___.

proliferate

23

 in CNS, oligodendrocytes shed myelin and ____.

 don’t usually proliferate

24

Main culprit of the glial scar = 

CSPG, chondroitin sulfate proteoglycans

25

CSPG, chondroitin sulfate proteoglycans are produced by

astrocytes in response to injury, inflammation, or disease

26

what are 6 Strategies to promote repair of the damaged nervous system:

1. biomaterials or peripheral nerve grafts

2. growth factors

3. agents to change local environement

4. cell replacement therapy to replace neurons or olgiodendrocytes

5. physical therapy

27

how can Chondroitinase ABC  help change local environements? 

its an enzyme that can remove sugar side chains from

inhibitory proteoglycans of the glial scar

28

Biomaterials or Peripheral Nerve Grafts could be used to provide a ____

a growth-promoting substrate

29

Growth factors could be used  to promote___ and ___

 neuronal survival and axonal sprouting

30

The perineurium is composed of extracellular matrix proteins that can promote ____

axon elongation after injury.

31

The key to successful regeneration in the periphery is the ____

Schwann cell.

A image thumb
32

regneerating axons can reconnect with target tissues because of guidance cues provided by ___ and ____

bunger and ach receoptors

A image thumb
33

why is the concept important that "if the neuron is lost it cant be replaced"

without the neuron, you cannot get repair (need surviving cell body)

34

what are some stem cell soruces?

A image thumb
35

in addition to replacing cells that were lost, what could stem cells also be useful for?

Differentiation of stem cells to oligodendrocyte progenitor cells prior to transplantation enhances the remyelination of spared axons near the lesion

36

physcial therapy can stimulate the endongeous poduction of ___ that promote repair

neutrophins