action potential n a momentary reversal in the potential difference across a plasma membrane (as of a nerve cell or muscle fiber) that occurs when a cell has been activated by a stimulus called also spike potential compare RESTING POTENTIAL see afterpotential, generator potential, prepotential
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the change in voltage that occurs across the membrane of a nerve or muscle cell when a nerve impulse is triggered. It is due to the passage of charged particles across the membrane (see depolarization) and is an observable manifestation of the passage of an impulse.
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(AP) the electrical activity developed in a muscle or nerve cell during activity. It may be elicited by electrical, chemical, or mechanical stimulation, by temperature change, and so on, and results from an influx of sodium ions so that the membrane potential becomes positive. See also all or none and discharge (def. 4).Medical dictionary. 2011.