PNS Axon injury and repair

Question 1

What cells assist in repairing damaged nerves

Answer 1

Schwann cells

Question 2

What is the repair process, which often fails to restore full function called?

Answer 2

Wallerian degeneration

Question 3

Describe the steps to repairing a broken axon

Answer 3

step 1- Distal to the injury site, the axon and myelin degenerate and fragment.
Step 2- Macrophages move into the area and remove the degenerating debris distal to the injury site.
Step 3- As the neuron recovers, its axon grows into the site of injury.
Step 4- The Schwann cells then wrap around it. If it grows correctly normal function will occur, but if it grows the wrong way or in a new direction normal function does not occur.

Question 4

Why is CNS more limited than PNS?

Answer 4

1. There are many more axons which are more likely to be involved.
2. Astrocytes produce scar tissue that can prevent axon growth
3. Astrocytes release chemicals that block the regrowth of axons