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Brain And Behavior Exam 4 > Lec 69 Neuronal Injury Regeneration Repair > Flashcards

Lec 69 Neuronal Injury Regeneration Repair Flashcards

1
Q

Is there inflammation in necrosis? apoptosis?

A

no inflammation in apoptosis

yes inflammation in necrosis

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2
Q

What is neurapraxia?

A

mild form of nerve damage; focal demyelination but axon itself not damaged

  • -> decreased/slowed conduction through damaged part only
  • -> heals completely in wks
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3
Q

Does demyelination decrease conduction velocity or decrease AP amplitude?

A

decreases conduction velocity

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4
Q

What is axonotmesis?

A

axon is disrupted/damaged but connecting tissue wrapping still intact

  • -> part of axon distal to injury will degenerate [wallerian] and proximal part eventually regenerates
  • -> heals in months
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5
Q

What is neurotmesis?

A

connective tissue wrapping of nerve is damage

  • -> difficulty regenerating axon
  • -> may have regrowth to wrong place
  • -> recovery poor
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6
Q

Do axons regenerate easier in PNS or CNS?

A

easier in PNS

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7
Q

What is mech of wallerian degeneration

A
  • intra-axonal organelle breakdown
  • schwann cells help axon breakdown and recruit more cells
  • macrophages clean up debris
  • path cleared for axons to grow proximal –> distal

= degeneration of injured axon distal to lesion in order to clear way for proximal part to regenerate

–> works well in PNS but not CNS

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8
Q

What is role of schwann cells in regeneration?

A

secrete stimulatory factors that help regeneration = regeneration-association genes [RAGs]

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9
Q

What are growth cones?

A

dynamic structures in PNS that grow using polymerization/depolymerization of actin/microtubules

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10
Q

What happens in axonal repair in CNS?

A
  • wallerian degeneration is inefficient –> myelin debris left behind + astrocytes lay down glial scarring
  • OLGs and astrocytes secrete inhibitors to regeneration [myelin inhibitors, scar tissue]
  • both CNS and aged neurons lack RAGs
  • failed regeneration –> retraction bulbs = contain disorganized array of microtubules
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11
Q

What are extrinsic inhibitors in CNS? what cells produce them?

A
  • oligodendrocytes –> myelin associated inhibitors
  • astrocytes –> chrondoitin sulfates
  • astrocytes + fibroblasts –> fibrous scar tissue
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12
Q

What is intrinsic growth potential in PNS vs CNS?

A 
PNS = 1-3 mm/day
CNS = 0.1 mm/day
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13
Q

What are extrinsic advantages of PNS regeneration?

A
  • schwann cells secrete stim factors vs OLGs/astrocytes in CNS inhibit
  • schwann start breakdown and recruit macrophages
  • OLGs in CNS slower clearing dead axon tissue; astrocytes make fibrous glial scar that blocks growth
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14
Q

What are intrinsic advantages of PNS?

A
  • PNS neurons express growth-related genes/regeneration associated genes = have intrinsic growth potential
  • in CNS = regeneration as slower pace if at all
  • PNS neurons have receptors and signal transduction machinery –> allows them to grow in response to neurotrophins and retrograde injury signals
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15
Q

What does failed regeneration look like?

A

try to regrow ad end in bulbs but stop = retraction bulbs

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16
Q

What are good prognostic factors for outcome?

A
  • reduced secondary damage via hypervigilant monitoring of vital signs, electrolytes, germs
  • aggressive prolonged rehabilitation
17
Q

What is CNS plasticity?

A

rerouting not regenerating of neurons = regulating multiple facotrs in CNS to get around the injury

18
Q

What are short term mech of neural plasticity?

A
  • synapse regulation = dendritic spine growth and pruning
  • receptor regulation = trafficking of receptors toward synaptic cleft + recycling them back
  • transmitter regulation
  • network adaptation and plasticity
19
Q

What is synapse regulation?

A

mech of short term neural plasticity

- make synapse stronger or weaker in order to increase learning

20
Q

What is example of network adaptation?

A

task training in single hand causes selective increase in baseline excitability of that muscle group

21
Q

What are long term mechs of neural plasticity?

A 
sprouting = rerouting of connections
pruning = consolidation of new circuits after period of regrowth [remove connections]
22
Q

How does learning skill help stimulation of cortical networks?

A

activity improves regeneration of netowkrs
learning variety of skilled, task-specific repetitive tasks = better than general exercise alone –> better stimulation cortical networks

repetitive tasks needed to maintain goals/consolidate circuits

23
Q

What are principles of rehabilitation?

A

promotes pruning of new connections

  • learned skilled, relevant tasks better than general exercise
  • -> skilled tasks stimulate cortical networks
  • -> task specific real life skill more motivating and prune
  • -> repetition maintains gains and consolidates circuits
24
Q

What is constraint-induced movement therapy?

A

constrain good limb in order to force pt to practice with injured limb = principle that hemispheres compete with each other via reciprocal inhibitory signals

physical restrain helps injured cortex promote plasticity

random practice order rather than ordered blocks

25
Q

Where are embryonic stem cells derived from?

A

blastocyst inner cell mass 4-5 days post fertilization

  • usually from excess IVF-derived embryos NOT aborted fetuses
  • source of pluripotent stem cells
26
Q

What are pluripotent stem cells?

A

can form endo/meso/ectoderm
cannot form trophoblast
immortal/renewable
no-autologous

27
Q

Where are fetal stem cells derived from?

A

fetal or extra-fetal tissue [amniotic fluid or umbilical cord blood]
does not necessarily disrupt fetal viability [but can come from aborted fetuses]
multipotent cells

28
Q

What are multipotent stem cells?

A

can differentiate into many but not all types

29
Q

Where are adult stem cells derived from?

A

mature tissues like bone marrow, skin, GI, adipose, cardiac, brain, dental pulp
oligopotent

30
Q

What are synonyms for adult stem cells?

A

mesenchyma stem cell

stromal stem cell

31
Q

What are oligopotent stem cells?

A

can differentiate into some cell types but basically lineage specific

ex. bone marrow stem cells –> all hematopoietic cell types

32
Q

What is somatic cell nuclear transfer?

A

adult somatic cell nuclei transferred into enucleated donor egg cells
adult nucleus reprogrammed by donor egg cytoplasm
pluripotent but not completely autologous

could use to clone animals

33
Q

What are induced pluripotent stem cells?

A

stem cell genes activated in adult somatic cells

have pluripotent stem cells that are 100% autologous

34
Q

What are uses of stem cells?

A
  • developmental studies
  • disease-specific cells for in vitro drug screening [to see which pt responds best to which drug]
  • cell transplants
  • organ transplants
35
Q

What are best targets for stem cells?

A

pathological processes that accept 1 type of neuron at 1 site

Brain And Behavior Exam 4 (24 decks)

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