Action potential and nervous conduction

An action potential is a transient depolarization of the membrane potential i.e. the cell membrane changes from a state where the inside of the cell is negative with respect to the outside to one where it is transiently positive. This event may last for about only one millisecond in a typical nerve or a skeletal muscle cell, but it may last for several hundred milliseconds in other cells (e.g. myocardium).