Electrophysiology

Abstract

Ions are charged particles, so movement of ions constitutes electrical charge movement that creates an electrical current. Ion movement or flux is controlled by both concentration gradients and electrical gradients. If these gradients are equal but opposite in direction for a particular ion, then its total electrochemical potential is zero, and there is no net current (I_ion) flow. This is a definition of electrochemical equilibrium. Ionic electrical current flows from an anode, an area of relatively positive electrical charge or a current source, to a cathode, an area of relatively negative electrical charge or a current sink.