ANATOMY

Detailed explanation-1: -The repolarization or falling phase is caused by the slow closing of sodium channels and the opening of voltage-gated potassium channels. As a result, the membrane permeability to sodium declines to resting levels.

Detailed explanation-2: -During repolarization, potassium ions move out of the cell via potassium channels. This movement is down the concentration gradient to restore the charges across the cell membrane.

Detailed explanation-3: -To summarize, sodium ions (Na+) enter the nerve membrane during depolarization and potassium ions (K+) leave the nerve membrane during repolarization.

Detailed explanation-4: -Membrane currents that generate the a normal action potential. Resting (4), upstroke (0), early repolarization (1), plateau (2), and final repolarization are the 5 phases of the action potential.