Dictionary of Biological Psychology
absolute refractory period
The period following an ACTION POTENTIAL during which it is impossible to elicit a second action potential. This property is the result of the activation and inactivation of sodium currents during an action potential.
The voltage-sensitive SODIUM CHANNELS cannot be activated (opened) while they are still inactivated from the previous action potential. Since sodium inactivation is dependent on DEPOLARIZATION, the cell membrane must be sufficiently repolarized for this inactivation to be removed. Only then can a new action potential be produced by a new depolarizing stimulus. The absolute refractory period imposes an upper limit on the frequency with which action potentials can occur.
DOUGLAS D.RASMUSSON
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