Lecture 10.3 Flashcards
What types of injury can you have when it comes to peripheral and central projections?
Central to central
central to peripheral
peripheral to peripheral
Where is the cell body when peripheral nervous system is damaged?
Can be in the peripheral ganglion or in the CNS
Can PNS have full, partial or no repair?
Often partial, may be full
Can CNS have full, partial or no repair?
Partial in turns of retracting their processes and sprouting new connections but usually none
What is a difference between dorsal root ganglion sensory neurons and spinal motor neurons in terms of regenerative capacity?
Simply that there are differences in time and capacity to do so between different types of neurons
What are the 3 broad areas of differences between the CNS and PNS that allows the PNS to regenerate neurons?
Structure
Cell types
Molecules
What produces myelin?
Schwann cells in PNS
Oligodendrocites in CNS
What occurs to neurons that are around 2 weeks post-injury? (first stage)
Pale in color
Wallerian degeneration
What is Wallerian Degeneration?
Degeneration of the axons and myelin sheath below the site of injury this causes muscle atrophy
What happens to the degenerated debris of the neuronal axon after a while?
The debris is phagocytosed by macrophages
What occurs to neurons that are around 3 weeks pos-injury? (second stage)
Schwann cells come to the site of injury and form a cord that connects to the two parts of the neuron
What is the last stage of PNS nerve regrowth?
Electrical activity can be restored therefore leading to muscle fibre regeneration
What occurs if there is unsuccessful regeneration?
A neuroma forms. This is a glob of the neuron endings have continued to grow but have missed their target
What is the basal lamina used for?
To help funnel parts of the axon to its target
What are growth cones?
They are the motile end of a GROWING axon that responds to signals within the environment
What are the Schwann cells role in peripheral nerve regeneration? 5 points
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)
What is GAP43?
It is a growth promoting protein that is increased when the need to re-grow axons occurs
What are some growth factors for motor neurons? Are they the same for sensory?
No, different neuronal types require different growth factors
NT3, GDNF, HGF, FGF
What are some growth factors for sensory neurons? Are they the same for motor?
No, different neuronal types require different growth factors
NGF, GDNF, NT3
What happened to the muscle when it is reinnervated by the regenerated axon?
Everything is innervated as it was before the injury however it can be less accurate
What is the best way to activate the newly regenerated system again?
Exercise
What is different about the PNS that allows for axonal regeneration?
The PNS provides an environment that is good for re-growth
