Repolarization of a nerve is due to: September 2009

Ans. B: Potassium ionsThe Na+ channels rapidly enter the inactivated state and remain in this state for a few milliseconds before returning to the resting state. In addition, the direction of the electrical gradient for Na+ is reversed during the overshoot because the membrane potential is reversed, and this limits Na+ influx.A third factor producing repolarization is the opening of voltage-gated K+ channels.The net movement of positive charge out of the cell due to K+ efflux at this time helps complete the process of repolarization.The slow return of the K+ channels to the closed state also explains the after-hyperpolarization.