Neural response to injury

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Various source of injury to neurons
mechanical, isachaemic, auto-immune, infections, genetic, metabolic, development
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What is wallerian degeneration?
Loss of the neuron in front of the axotomic cut. Anterograde degeneration
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What is the first thing to happen after axotomy?
Terminal degeneration
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What follows terminal degeneration?
Wallerian degeneration
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After what does macroglia macrophage infiltrate?
myelin debris
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Chromatolysis happens after macroglia infiltrate, what is it?
dissolution of the Nissl bodies in the cell body of a neuron.
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What happens after chromatolysis?
retraction of the synaptic terminals, glial cell ensheathement
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The last thing to happen in axotomy?
transneuronal degeneration - the one the neuron would have synapsed on degenerates.
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What phenomenon can mask the effects of axotomy?
Collateral sprouting
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What is a possible mediator for retrograde effects of axotomy?
Lack of neurotrophin
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What is a possible mediator for orthograde effects of axotomy?
Lack of factors from the cell body that suppress and inbuild degeneration programme
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Biochemical events in the degrading axon?
Ca+ entry, calpain activation, release of FGFs
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Biochemical events in the cell body?
Upregulation of c-Jun, Gap-43 and CGRP in motor neurons. Down regulation of Neurofilaments, LNGFR in sensory neurons.
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Biochemical events in the schwann cell?
Down-regulation of myelin associated proteins. Upregulation of NCAM, L1, IGFs
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Things an axon needs to successful repair in cut axons
Accurate guidance, vigourous regrowth which needs - the cell body to reprogramme protien synthesis for growth, and a local environement that encourages growth
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How does the PNS evironment encourage regrowth?
The schwann cells upregulate LI, NCAM, BDNF, NGF, IGFI and 2
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What helps accurately guide the axons in regrowth?
The basal lamina tubes, if they stay intact.
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What causes protien synthesis in the cell body?
up-regulation of c-Jun, GAP-43, actin and tubulin,
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What growth inhibiting factors are present in the CNS?
Proteoglycans (astrocytes) , myelin associated glycoprotiens and NOGO (oligodendrocytes)
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Card 2

Front

What is wallerian degeneration?

Back

Loss of the neuron in front of the axotomic cut. Anterograde degeneration

Card 3

Front

What is the first thing to happen after axotomy?

Back

Preview of the front of card 3

Card 4

Front

What follows terminal degeneration?

Back

Preview of the front of card 4

Card 5

Front

After what does macroglia macrophage infiltrate?

Back

Preview of the front of card 5
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