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Cutaneous Receplors: Pacinian Corpuscle

NEUROPHYSIOLOGY

Generator poiential

Centr.nl core Unmyclinatcd axon terminal

A. Sliarp 'on and o fi" changes in pressure at start and end of pulse applted to lamellated rapsule are tnnsmitted to central axon and provokc generator potentials,, which in tum may triggcr action potentials; there is no response to a slow change in pressure gradient. Pressure at central core and. accnrdingły. generator potentials arc rapidly dissipated hy viscoelastic pnoperties of capsule (Action potentials may be hlodced by pressure at a nodo or by drugsi

B. In abscncc of capsule, axun responds lo slow as well as to rapid changes in pressure. Generator potential dissipates slowly, and there is no "off" response

Generator potential

via rapsule causes inrreased permeability of membranę to Na*, thus setting up ionir generator current through 1 st node

C '-m' ~" ~

If resultant depolarutation at lst node is great enough to reach threshold, an action potential appears which is propagated along nr*rve fiber

Figurę 2.24 Pacinian Corpuscle_

Pacinian corpuscle* arc mechanoreceptors that transduce mechani-cal forces (displacement, pressure, vibration) into action potentials that are conveyed centrally by afferent nerve fibers. As the viscoelas-tic lamellae are displaced, the unmyelinated axon terminal membranę^ ionic permeability is inereased until it is capablc of producing a "generator potential.' As demonstrated in the llRure, pacinian cor-puscles respond to the boginning and end of a mechankral force while the concentnc lamellae dissipatc slow changes in pressure. In the absence of the capsule, the generator potential decays slowly and yields only a single action potential.

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