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6 Cards in this Set
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- Back
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Neuroglia - describe. . . Schwann cells / Neurolemmocytes Oligodendrocytes Microglia |
Schwann cells / Neurolemmocytes - form myelin sheaths around axons of PNS Oligodendrocytes - form myelin sheaths around axons of CNS Microglia - phagocytic cells, migrate through CNS |
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Neuroglia - describe . . . Astrocytes Ependymal cells Satellite cells |
Astrocytes - star-shaped cells surrounding capillaries in brain; form blood-brain barrier; structural support Ependymal cells - epithelial cells lining ventricles of brain & central canal of spinal cord; form & circulate CSF Satellite cells - support neurons in PNS ganglia |
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Axon sheath - Unmyelinated Function & description |
Surround & protect, insulate axons Unmyelinated neurons - rest in invagination of Oligodendrocytes or Schwann cells |
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Axon sheath - Myelinated Function & description |
Surround & protect, Insulate axons Myelinated neurons - successive wrappings of Schwann or Oligodendrocytes around axon form myelin sheath; cell wraps around axon > cytoplasm pushed to the outside > gaps in between cells are "nodes of ranvier" |
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Myelinated Axon Sheath - is regeneration possible in PNS or CNS? |
PNS - schwann cells wrap around a single axon, regeneration is possible CNS - single oligodendrocyte forms myelin sheath around several axons, no regeneration |
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Regeneration of cut axon (PNS) 3 steps |
1. Chromatolysis - breakdown of nissl bodies 2. Degeneration of axon - Wallerian: distal to injury, Reterograde - proximal to injury to 1st node near cell body 3. Schwann cells form a regeneration tube, secrete chemicals that attract axon, guide its growth to reconnect to receptors/effectors |
