Nerve velocity is increased by:
Correct Answer: Myelination
Description: Ans: A (Myelination) "Greater the diameter of a given nerve fibre, the greater is its speedfbecause a large fiber offers less resistance to local current"- A. K. jain 5th/l 47In myelinated fibres, the speed of conduction is approximately 6 times the fiber diameter The diameter of myelinated fibers range from 1-20 pm, therefore conduction velocity varies from 6-120 m tsfsec"- A.K.jain 5th/l 47SALTATORY CONDUCTION Ganong 24th/ 91Conduction in myelinated axons depends upon a similar pattern of circular current flow. However, myelin is an effective insulator, and current flow through it is negligible. Instead, depolarization in myelinated axons jumps from one node of Ranvier to the next, with the current sink at the active node serving to electrotonically depolarize to the firing level the node ahead of the action potentialThis jumping of depolarization from node to node is called saltatory conduction. It is a rapid process, and myelinated axons conduct up to SO times faster than the fastest un myeiina ted fibers.
Category:
Physiology
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