Lecture 10.3

Question 1

What types of injury can you have when it comes to peripheral and central projections?

Answer 1

Central to central
central to peripheral
peripheral to peripheral

Question 2

Where is the cell body when peripheral nervous system is damaged?

Answer 2

Can be in the peripheral ganglion or in the CNS

Question 3

Can PNS have full, partial or no repair?

Answer 3

Often partial, may be full

Question 4

Can CNS have full, partial or no repair?

Answer 4

Partial in turns of retracting their processes and sprouting new connections but usually none

Question 5

What is a difference between dorsal root ganglion sensory neurons and spinal motor neurons in terms of regenerative capacity?

Answer 5

Simply that there are differences in time and capacity to do so between different types of neurons

Question 6

What are the 3 broad areas of differences between the CNS and PNS that allows the PNS to regenerate neurons?

Answer 6

Structure
Cell types
Molecules

Question 7

What produces myelin?

Answer 7

Schwann cells in PNS

Oligodendrocites in CNS

Question 8

What occurs to neurons that are around 2 weeks post-injury? (first stage)

Answer 8

Pale in color

Wallerian degeneration

Question 9

What is Wallerian Degeneration?

Answer 9

Degeneration of the axons and myelin sheath below the site of injury this causes muscle atrophy

Question 10

What happens to the degenerated debris of the neuronal axon after a while?

Answer 10

The debris is phagocytosed by macrophages

Question 11

What occurs to neurons that are around 3 weeks pos-injury? (second stage)

Answer 11

Schwann cells come to the site of injury and form a cord that connects to the two parts of the neuron

Question 12

What is the last stage of PNS nerve regrowth?

Answer 12

Electrical activity can be restored therefore leading to muscle fibre regeneration

Question 13

What occurs if there is unsuccessful regeneration?

Answer 13

A neuroma forms. This is a glob of the neuron endings have continued to grow but have missed their target

Question 14

What is the basal lamina used for?

Answer 14

To help funnel parts of the axon to its target

Question 15

What are growth cones?

Answer 15

They are the motile end of a GROWING axon that responds to signals within the environment

Question 16

What are the Schwann cells role in peripheral nerve regeneration? 5 points

Answer 16

They support intact axons for growth

Form peripheral myelin

Secrete molecules required for successful regeneration (Laminin, Fibronectins and Collagen) for structural support

Increase expression of cell surface molecules such as L1 which bind to receptors on regenerating axons

Near site of injury, increase expression of neurotrophic factors such as Brain derived neurotrophic factor (BDNF)

Question 17

What is GAP43?

Answer 17

It is a growth promoting protein that is increased when the need to re-grow axons occurs

Question 18

What are some growth factors for motor neurons? Are they the same for sensory?

Answer 18

No, different neuronal types require different growth factors
NT3, GDNF, HGF, FGF

Question 19

What are some growth factors for sensory neurons? Are they the same for motor?

Answer 19

No, different neuronal types require different growth factors
NGF, GDNF, NT3

Question 20

What happened to the muscle when it is reinnervated by the regenerated axon?

Answer 20

Everything is innervated as it was before the injury however it can be less accurate

Question 21

What is the best way to activate the newly regenerated system again?

Answer 21

Exercise

Question 22

What is different about the PNS that allows for axonal regeneration?

Answer 22

The PNS provides an environment that is good for re-growth