At the end of repolarization, the nerve is hyperpolarized. How does the membrane potential return to RMP?
Simultaneously with the action of the pump, there is inward diffusion of Na+ through the leaky channels (not the voltage-gated channels that cause depolarization). This inward leakage of positive charges will take the membrane potential from - 90 mV to original RMP of - 70 mV. Both the pump and the inward leakage will balance out once the potential again reaches - 70 mV.
Action of Na+/ K+ -pump
Inward leakage of Na+
Decrease in K+ efflux
None of the above mechanisms
Excitation and Action Potiential