BIOLOGY 2C03 Lecture Notes - Microglia, Phagocytosis, Macrophage
28 Jan 2013
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Document Summary
Myelination: schwann cells and oligodendrocytes: the myelin forming cells of the pns and cns. Myelin sheaths speed conduction and cause saltatory conduction. Spaces between sheaths, the nodes of ranvier, are sites of dense na channels, where action potential is regenerated: schwann cells (3 types) Satellite cells: found in enteric system, isolate neurons from surrounding environment. Ensheathing schwann cells: surround nonmyelinated pns axons, multiple axons per sc. One axon per schwann cell; the axon induces myelin formation. Unrolled forms trapezoid shape, explains distinctive edge morphology. Major dense line is the cytoplasmic face of membrane; intraperiod line is extracellular face. Does not divide further unless disease or injury to neuron, in which case schwann cells divide to replace sheath and provide support for axonal growth: oligodendocytes. Myelinates axons in the cns, many axons per oligodendrocyte. The notes provides nice review for lecture 09 (02-20 b; bergles) astrocytes. Function as the immune system of the cns.
