Myelin Sheath
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The myelin sheath is the insulating coating of neuron made up largely of fat. It covers each axon. Because myelin is slippery and wet it increases the speed at which the electrical impulse is carried, thus increasing the velocity of nerve impulse. (See Node of Ranvier). Myelin covers some but not all vertebrate axons. Axons that are myelinated appear white and are therefore referred to as "white matter" (as opposed to "grey matter") in the central nervous system. |
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