Facebook Pixel
Brookbush Institute Logo
Action Potential Thumbnail

Glossary Term

Action Potential

An action potential is a rapid change in voltage that results in a wave of excitation, which may stimulate a nerve or muscle cell. This process requires the resting membrane voltage to exceed the excitation threshold, resulting in depolarization and the 'wave of excitation.' The action potential functions like an on/off switch, and any stimulus below the threshold will not result in an action potential. Synonyms include nerve impulse, action current and, spike potential.

Action Potential: A rapid change in voltage, resulting in a wave of excitation, that may result in stimulation of a nerve or muscle cell.

  • In order for an action potential to be initiated, the resting membrane voltage must exceed the excitation threshold, which then results in a cascade of depolarization and the "wave of excitation." Any stimulus below that threshold will not result in an action potential, and a stimulus greater than the threshold will not increase a single action potential, but may result in additional action potentials. In this way, the action potential functions more like an on/off switch (all or none), and less like a dimmer switch.

Image: Original by en:User:Chris 73, updated by en:User:Diberri, converted to SVG by tiZom - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2241513




  1. Nerve Impulse
  2. Action Current
  3. Spike Potential