Origin of the resting potential

Three main factors contribute to the resting potential: (i) the smaller permeability of the membrane to Na/sup +/ compared to K/sup +/, in conjunction with a neutral Na/sup +/-K/sup +/ pump; (ii) the excess intracellular concentration of indiffusible anions; and (iii) the electrogenic component of the Na/sup +/-K/sup +/ pump. In this article, a novel approach is used to explain the origin of the resting potential in terms of the these three factors. The explanation, based on an idealized model to which successive changes are made to account for each of these contributions, is primarily descriptive, relying on fundamental principles, but it is extended to include considerations of the electrochemical potential and the equivalent circuit.