11 - Injury and repair of the Nervous System Flashcards
Where does nerve regeneration occur?
In the PNS
What is axonal damage?
When the flow of information is damaged in an axon and the site is filled with debris
What is anterograde degeneration?
Damage spreads towards dendrites
What is trans-neural degeneration?
Damage spreads to other axons
What is neurapraxia?
1st degree neuronal damage, temporary loss of motor and sensory function due to blockage
What is axonotmesis?
2nd degree neuronal damage, disruption of axons due to sever, crush or contusion
What is retrograde degeneration?
Damage spreads towards cell body
What is neurotmesis?
3rd degree neuronal damage, both axons and nerve sheath are disrupted - irreversible
What occurs straight after nerve damage?
A burst of action potential to let dorsal root ganglion know of damage
There is disruption in retrograde flow
Neurotrophic factors are released to promote regeneration
Cells in DRG switch transmission to growth state so ion levels decrease and increase in levels of proteins involved in axonal growth
What is chromatolysis?
Precursor to apoptosis, nucleus moves towards the cell edge
What occurs during nerve regeneration?
Schwann cells divide - secrete trophic factors to attract axons - remyelinate new axons - 1mm/day growth rate
- if connective tissue is damaged then it is likely the nerve will not be able to regenerate
What are some challenges in nerve repair?
Nerve damage may spread
Nerve repair - not always successful due to unmatched sensory and motor nerves
Success depends on the severity of the injury
What is wallerian degeneration?
When the axon is separated from the neuron cell body
What is a tubular repair?
A silicon tube or other material is used to fill the gap where damage has occurred
What are 3 neurotrophic growth factors?
NGF - Nerve Growth Factor
BDNF - Brain Derived Neurotrophic factor
GDNF - Glial cell derived neurotrophic factor
Neurotrophic growth factors promote axon regeneration and are taken up by nerve terminals
