nerve regeneration

Question 1

pressure or damage reduces what to neuron? how long for 1-2 hours of pressure? 2 hours of pressure? do neurons respond to injury? neurons have centrioles and do they divide? regeneration good? is nerve conduction lost?

Answer 1

pressure or damage reduces blood flow and O2 to neuron
-unexcitable membrane

1-2 hours of pressure + 2 weeks for neuron recovery
2 hours pressure + permanent damage ~ cutting axon

neurons response to injury ~ very limited and rare

neurons ~ no centrioles ~` cannot divide

regeneration is never as good as prior to injury

nerve conduction is lost

Question 2

cns regeneration ~ brain and spinal cord repair

is there a poor chance of functional recovery? is there a complicated repair process?

Answer 2

poor chance of functional recovery

complicated repair process

1. many more axons affected
2. astrocytes produces permanent scar tissue
3. many chemicals in CNS inhibit re-growth

Question 3

peripheral nervous system regeneration ~ nerve repair

what is wallerian degeneration?

Answer 3

the repair process

Question 4

peripheral nervous system ~ nerve repair

steps of axon regeneration

what are the 5 steps of axon regeneration?

1/axon is.., 2a/proximal to the cut.., 2b/distal to the cut.., 3/neurilemma and endoneurium forms.., 4/axon regenerates guided by.., 5/axon reinnervates..

Answer 4

1/axon is severed by trauma

2a/proximal to the cut: the axon seals off and swells

2b/distal to the cut: the axon and sheath degenerate (wallerian degenration) but the neurilemma survives

3/neurilemma and endoneurium form a regeneration tube

4/axon regenerates guided by nerve growth factors released by neurolemmocytes

5/axon reinnervates original effector or sensory receptor