Re/Degeneration in the Nervous System Flashcards
Most injuries to the nervous system affects the _____
Axon (axotomy/axontmesis)
Injury to the axon divides the neuron into:
- Proximal portion that retains its attachment to the cell body
- Distal fragment
The proximal part of the axon and cell body is likely to:
Die by apoptosis
If the proximal part of the axon and cell body does not die by apoptosis, the cell body undergoes:
Chromatolytic reaction
The distal segment of the injured axon undergoes:
Wallerian degeneration
The postsynaptic neuron is affected because of a lack of input, and eventually atrophies and dies
Transneuronal anterograde degeneration
The neuron that provides the injured cell with input also undergoes changes
Transneuronal retrograde degeneration
What happens during chromatolytic reaction?
- Eccentric nucleus (nuc. starts shifting)
- Nissl substance fragmentation
- Inc. of RNA and protein synthesis
- Changes in the expression of the neuron’s genes
What happens during Wallerian degeneration?
- Axonal degeneration
- Myelin sheath fragmentation
- Axonal and myelin debris is enveloped and destroyed by microglia
_____ have a higher capacity to regenerate after injury than _____
- Peripheral neurons
- Central neurons
Connective tissue elements survive in the _____ of the axotomized neuron
Distal fragment
Grows axonal sprouts that are guided to the distal portion by chemotropic factors secreted by schwann cells
Proximal fragment
If axonal sprouts do not make contact with the distal element, the become intangled and form a benign mass
Neuroma
Both the CNS and PNS can secrete what after injury?
Growth promoting factors
