ANSC 2340 Lecture Notes - Lecture 5: Myelin, Peripheral Nervous System, Saltatory Conduction
13 Apr 2018
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Document Summary
Structure of neurons: white matter = nervous tissue with many myelinated axons. Grey matter = nervous tissue w/o myelin stains dark, primarily in neuron cell bodies. Myelin = white fatty substance that covers axons. Myelin sheath functions as the cell membrane for specialized, functional glial cells called: Oligodendrocytes inside brain + spinal cord (sc) Schwan cells outside brain and spinal cord (sc) Myelinated axons get faster speed transmission than unmyelinated axons. Specialized glial cells are wrapped around axon which can be 1 to several feet long, would require multiple oligodendrocyte or schwann cells to cover axon. Nodes of ranvier = gaps present between adjacent glial cells. Myelin sheaths and nodes of ranvier work together to speed up transfer of the nerve impulse. Deals with central or cranial-caudal axis of the body. Includes nerves that radiate from cns to all other parts of the body. Cranial nerves: pns nerves that originate from brain.
