<P> In physiology , a refractory period is a period of time during which an organ or cell is incapable of repeating a particular action , or ( more precisely ) the amount of time it takes for an excitable membrane to be ready for a second stimulus once it returns to its resting state following an excitation . It most commonly refers to electrically excitable muscle cells or neurons . Absolute refractory period corresponds to depolarization and repolarization , whereas relative refractory period corresponds to hyperpolarization . </P>
the absolute refractory period in cardiac muscle cells is
period of time during which an organ or cell is incapable of repeating a particular action , or ( more precisely ) the amount of time it takes for an excitable membrane to be ready for a second stimulus once it returns to its resting state following an excitation .