AP PSYCHOLOGY

Detailed explanation-1: -Repolarization is caused by the closing of sodium ion channels and the opening of potassium ion channels. Hyperpolarization occurs due to an excess of open potassium channels and potassium efflux from the cell.

Detailed explanation-2: -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-3: -The falling phase of the action potential is caused by the inactivation of the sodium channels and the opening of the potassium channels. After approximately 1 msec, the sodium channels inactivate. The channel becomes blocked, preventing ion flow. At the same time, the voltage-gated potassium channels open.

Detailed explanation-4: -In neurons, the rapid rise in potential, depolarization, is an all-or-nothing event that is initiated by the opening of sodium ion channels within the plasma membrane. The subsequent return to resting potential, repolarization, is mediated by the opening of potassium ion channels.

Detailed explanation-5: -The repolarization phase of the action potential involves decreasing sodium influx via inactivation of sodium channels and increasing potassium efflux (exit) via opening potassium channels.