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21 Cards in this Set
- Front
- Back
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why is the CNS so difficult to repair? |
1. CNS injury often leads to neural death 2. astrocytes actively inhibit axon growth 3. neural stem cells in brain are largely constrained in their ability to divide, migrate, and differentiate |
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3 types of NS repair |
1. restoration of damaged neurons 2. glial overgrowth 3. generation of new neurons |
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restoration of damaged neurons |
requires reactivation of developmental processes for axon growth and guidance and synapse formation |
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glial overgrowth |
1. injury occurs to cell body of neurons 2. results in retraction of axons 3. involves growth of glial cells that inhibit axonal growth |
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generation of new neurons |
1. rare process 2. localized brain regions (ex: hippocampus and olfactory bulb) 3. requires population of neural stem cells in vincinity |
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macrophages |
degrade distal part of degenerated axon |
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regenration: cutting nerve |
1. distal part of axon degenerated and degraded by macrophages 2. proximal end of axon forms new growth cone 3. regrowth possible |
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regeneration: crushed nerves |
1. regorwth occurs more efficiently and quickly |
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essential mediatory of PNS growth |
Schwaan cells |
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Schwaan cells |
1. essential mediatory of PNS growth 2. provide support 3. secrete ECM molcules 4. increases expression of cell adhesion molecules in response to injury |
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three main causes of CNS injury |
1. external physical trauma 2. hypoxia - lack of oxygen to brain 3. neurodegenerative disease |
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apoptosis |
1. programmed cell death 2. suicide program activated within a cell 3. leads to rapid cell death mediated by proteolytic enzymes |
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necrosis |
1. death of cells or tissues via injury or disease 2. typically due to a lack of support 3. without regulation of an intracellular mechanism |
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cellular response to CNS injury |
1. degeneration fo distal portion of axon 2. microglia and phagocytic cells clear degenerating axon and myelin 3. proliferation of glial cells --> production of inhibitory factors --> axon regrowth |
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what cell types does CNS injury elicit a response from? |
glial cells 1. astrocytes 2. oligodendrocytes 3. microglia |
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capases |
1. regulate apoptosis |
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initiator capases |
capase 2,8,9,10 |
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executioner capase |
capase 3,6,7 |
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cytochrome c |
1. found within mitochondria 2. released into cytoplasm at the onset of apoptosis underlies apoptosis |
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Extracellular survival factors |
inhibit apoptosis |
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PI3-kinase signaling |
underlies cell survival |
