MEDICAL PHYSIOLOGY

Detailed explanation-1: -The diffusion of potassium ions out of a neuron causes regain of resting potential. The resting membrane potential is restored due to action of voltage gated (K+) channels which open due to membrane depolarisation and cause efflux of (K+) ions out of the neuron. It continues till the resting potential becomes-70 mV.

Detailed explanation-2: -Once depolarization is complete, the cell must now “reset” its membrane voltage back to the resting potential. To accomplish this, the Na+channels close and cannot be opened. This begins the neuron’s refractory period, in which it cannot produce another action potential because its sodium channels will not open.

Detailed explanation-3: -Depolarization also opens voltage-gated K+ channels, allowing K+ efflux, which, together with rapid Na+ channel inactivation, quickly repolarizes the membrane during the falling phase of the action potential. This enables the cell to propagate electrical signals quickly and with high efficiency.

Detailed explanation-4: -A set of voltage-gated potassium channels open, allowing potassium to rush out of the cell down its electrochemical gradient. These events rapidly decrease the membrane potential, bringing it back towards its normal resting state.

Detailed explanation-5: -To return to the resting potential from the undershoot, which went to the equilibrium potential of K+, the cell must reset. The inactivation plug is removed from the Na+ voltage-gated channels, and the activation gate is closed. The K+ voltage dependent channels close, stopping the flow of K+ out of the cell.