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Saltation |
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saltation [sȯl′tā·shən]
(geology) Transport of a sediment in which the particles are moved forward in a series of short intermittent bounces from a bottom surface. Saltation the intermittent conduction of a nerve impulse along myelinated nerves, whose sheath has a relatively high resistance to electric currents. Regular (every 1–2 mm) microscopic constrictions in the myelin sheath, called the nodes of Ranvier, are found along the length of the nerve. Nerve-impulse conduction along internodal sections is achieved electro-tonically, although the weakening of an impulse is reduced by the insulating properties of myelin. Upon reaching the next node of Ranvier, a signal again increases in strength to the standard level as a result of the generation of an action potential. Thus, the reliable and economical conduction of an impulse along a nerve fiber is ensured: an impulse seems to jump from one node of Ranvier to another. Want to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit the webmaster's page for free fun content. |
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