Module 3.3- Regeneration and Repair in the Nervous System

Question 1

Are Neurons capable of mitosis?

Answer 1

No, with very few exceptions

Question 2

Can nerve cells lost to injury or disease be replaced?

Answer 2

No.

Question 3

If the neuronal cell body is still healthy post injury, can the axon regenerate?

Answer 3

Yes except in the central nervous system.

Question 4

Why can’t central nervous system neurons regenerate?

Answer 4

They are myelinated by oligodendrocytes rather than Schwann cells.
After axonal damage, nearby astrocytes rapidly proliferate forming scar tissue, which is a physical barrier to regeneration.

Question 5

Is injury to the brain and/or spinal cord usually permanent?

Answer 5

Yes, however some recovery of function can occur by use of the remaining uninjured neuronal tissue

Question 6

How can someone recover functions after Central Nervous System injuries?

Answer 6

By learning to use the remaining uninjured neuronal connections through therapy.

Question 7

Are peripheral axons capable of repair?

Answer 7

Yes, if cell body is intact, Schwann cells are functional and the formation of scar tissue doesn’t occur too rapidly.

Question 8

What three things must be present/occur for peripheral axons and dendrites associated with neurolemma to undergo repair?

Answer 8

Cell body must be intact
Schwann cells must be functional
Scar tissue formation cannot occur too rapidly

Question 9

What do most nerves in the Peripheral Nervous system consist of?

Answer 9

Processes covered with a neurolemma

Question 10

What factors affect the likelihood of functional recovery of the peripheral nervous system?

Answer 10

How close to the nerve cell the injury is (the more proximal a nerve injury is, the less likely it is to recover).
Whether or not nerve sheath is disrupted (a crushed nerve has better chance of recovery than a cut nerve)

Question 11

Can damage to a nerve cell body cause death of that cell?

Answer 11

Sometimes, if damage is serious enough.

Question 12

What are two examples of disease damage to nerve cells causing permanent cell death?

Answer 12

Paralytic Poliomyelitis in humans

Some forms of nervous Distemper in Canines

Question 13

Is injury that occurs to nerve processes more common in the central or periphery nervous systems?

Answer 13

Periphery

Question 14

Is injury to the nerve processes permanent?

Answer 14

It may or may not be, depending on the kind of injury and what part of the nervous system the injury occurs in

Question 15

What are three examples of injury to the nerve processes?

Answer 15

Limb going to sleep due to pressure on nerve trunk.
Crushing (eg. during childbirth)
Cutting a nerve (eg. by barbed wire)

Question 16

Following damage from crushing or light pressure, what do nerves do?

Answer 16

Frequently recover spontaneously in the short time following the injury.

Question 17

When a nerve is injured by a cut, under what circumstances will regrowth occur?

Answer 17

If it occurs in the peripheral nervous system and if the cell body and proximal segment remain healthy.

Question 18

How is a nerve that has been regrown from a cut injury different to that of a normal uninjured nerve?

Answer 18

The regrown nerve is usually less functional and transmits impulses slower

Question 19

What are some of the variable clinical signs of central nervous system damage?

Answer 19

Partial or complete paralysis (spinal cord lesions)
Spasms or convulsions
Impaired vision and/ or hearing
Cutaneous sensations

Question 20

What can cause Central Nervous system damage?

Answer 20

Can be caused by trauma (injury), tumours, infections or toxins (lesions)

Question 21

What does peripheral nervous system damage result in?

Answer 21

Loss of sensation and/or muscle activity in the area specifically supplied by the damaged nerve/s