Injury and repair of nervous system Flashcards
What is the purpose of donor axons when a limb is transported?
Act as temporary scaffold for axons to grow into
What is Wallerian degeneration?
Degeneration of the axon distal to the injury
What is retrograde degeneration?
Degeneration in opposite direction to Wallerian- in direction of cell body
What is transneuronal degeneration?
Degeneration of numerous neurons due to loss of input from one damaged axon
What does success of nerve repair depend on?
Severity of initial injury and extent of secondary damage
Define neuropraxia- what structures are damaged
Temporary loss of motor and sensory function due to blockage of nerve conduction.
Myelin is mainly affected, axon intact.
Define axonotmesis- what structures are damaged
Disruption of axons following severe crush or contusion. Both myelin and axon damaged, so Wallerian degeneration may occur. Epineurium intact so good chance of recovery
Define neurotmesis- what structures are damaged?
Both axons and nerve sheath damaged. Usually irreversible
What is the first step that occurs after nerve damage occurs?
Burst of action potentials
Disruption of retrograde transport flow of trophic support
Describe normal pathway of neutrophic factors
Released by innervated cells and taken up by nerve. Transported retrograde to cell body to promote neuronal growth and survival
How do cells in dorsal root ganglion respond to positive injury signal?
Alter their phenotype. Neurons switch from transmission state to growth state. Decrease in ion channels and proteins involved in neurotransmission. Upregulation of proteins involved in axonal growth
Role of Shwann cells in regenerating neurons?
Shwann cells divide
Secrete trophic factors to attract axon
Remyelinate new axon
Are CNS injuries more debilitating higher or lower in spinal cord?
HIgher
Define epicentre
Site of primary cell death in CNS injury
How is glial scar formed?
macrophages and microglia engulf debrif forming glial scar
