Neuronal Injury Flashcards
What can cause neuronal injury?
cutting, crushing, or shearing injury
What does the survival of an injured nerve cell depend on?
the distance of the injury away from the nerve cell body
What is chromatolysis?
the ‘healing’ process a neuron goes through a when the nerve cell body is likely to survive
What happens to the neuron in chromatolysis?
the cell body swells, nuclear displacement to eccentric position, and dispersion of ribosomes
What is the epineurium?
the connective tissue that bundles the bundles of axons
What is perineurium?
the connective tissue that bundles the axons
What is endoneurium?
the connective tissue that surrounds an axon
What cells initiate myelination in the peripheral nervous system?
schwann cells
What is the purpose of myelination?
to increase the speed of conductance
What process occurs when there is axonal injury in the PNS?
wallerian degeneration
What occurs during wallerian degeneration?
axon is cut off from the cell body, the distal axon dies, myelin reacts, schwann cellls assist in breakdown of axons with lysosomes, macrophages phagocytose axon and myelin debris
Schwann cells make and release growth factors, what do they do?
support nerve survival and axonal sprouting
In order for successful neuronal development, what must occur?
the nerve cell myst enter appropriate endoneurial tube
What can cause an injured nerve to fail to repair?
formation of a scar or entering the inappropriate endoneurial tubes
How are amputation neuromas caused?
sensory neurons are looking for their appropriate endoneurial tube but they cannot reach it so they grow into bundles causing phantom pain
If a CNS neuron is injured, what is the likely outcome?
Wallerian degeneration will occur, chromatolysis will occur but cells are more likely to die, microglia will invade, and there will be no regeneration of axons
What is the difference between the glia in the CNS and the PNS?
the glia in the PNS secrete growth factors and the glia in the CNS secrete inhibitory molecules that inhibit axon growth
True or False: CNS has no endoneurium.
TRUE
What cells myelinate axos in the CNS?
oligodendrocytes
Why are olfactory ensheathing cells (OES) used in experimental trials for nerve injury repair?
because they can phagocytize axonal debris and express growth factors to influence axon growth
