Why does an action potential travel down an axon?
The basic unit of nerve transmission is the action potential. An action potential is a brief electrical signal that travels along an axon at great speed. The action potential is a rapid change in the relative ion concentrations on either side of the cellular membrane and a rapid return to the original concentrations. The change in ion concentration is called a depolarization of the membrane. The transmission of the action potential is caused by three properties of the system. The depolarization spreads to adjacent areas, the depolarization is self-correcting, and during the recovery period depolarization cannot re-occur. Therefore when an action potential starts it triggers further depolarization but only in the direction along the axon in which depolarization has not already occurred. View the animation below, then complete the quiz to test your knowledge of the concept.
