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Flashcards in Neuroregeneration Lec24 Deck (36)
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1
Q

Nerves can sometimes regenerate in the ___

A

PNS

2
Q

Nerves can almost never regenerate in the ___

A

CNS

3
Q

Effective nerve regeneration requires: (4)

A

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
Q

after injury CNS Wallerian degeneration is ___ and ___

A

slow and incomplete

5
Q

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

A

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
Q

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

A

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

7
Q

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

A

degenerated and its myelin sheath degraded

8
Q

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

A

schwann cells and macrophages

9
Q

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

A

Schwann cell migration & axon regeneration

10
Q

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

A

bands of Bungner

11
Q

bands of Bungner guide the___ to their targets

A

growth cones

12
Q

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

A

apoptose

13
Q

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

A

months to years

14
Q

compared to the original, the regenerated axon will have

A

thinner myelin and shorter nodal length

15
Q

why are come compression injuries easier to repair?

A

some axons may be spared - easier to repair.

16
Q

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

A

Reinnervation

17
Q

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

A

1. clearence of debris

2. a supportive environment

3. guidance cues

18
Q

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

A

Ca influx and activation of calpain

19
Q

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

A

 24-48

20
Q

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

A

72

21
Q

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

A

increased glial support (astrocytes and macrophages) to clear debris

22
Q

 in PNS, Schwann cells shed myelin and ___.

A

proliferate

23
Q

 in CNS, oligodendrocytes shed myelin and ____.

A

 don’t usually proliferate

24
Q

Main culprit of the glial scar = 

A

CSPG, chondroitin sulfate proteoglycans

25
Q

CSPG, chondroitin sulfate proteoglycans are produced by

A

astrocytes in response to injury, inflammation, or disease

26
Q

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

A

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
Q

how can Chondroitinase ABC  help change local environements? 

A

its an enzyme that can remove sugar side chains from

inhibitory proteoglycans of the glial scar

28
Q

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

A

a growth-promoting substrate

29
Q

Growth factors could be used  to promote___ and ___

A

 neuronal survival and axonal sprouting

30
Q

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

A

axon elongation after injury.

31
Q

The key to successful regeneration in the periphery is the ____

A

Schwann cell.

32
Q

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

A

bunger and ach receoptors

33
Q

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

A

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

34
Q

what are some stem cell soruces?

A
35
Q

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

A

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

36
Q

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

A

neutrophins