AP PSYCHOLOGY

Detailed explanation-1: -[3][4] The Na+K+-ATPase pump helps to maintain osmotic equilibrium and membrane potential in cells. The sodium and potassium move against the concentration gradients. The Na+ K+-ATPase pump maintains the gradient of a higher concentration of sodium extracellularly and a higher level of potassium intracellularly.

Detailed explanation-2: -Acetylcholine diffuses across the cleft and binds to nicotinic acetylcholine receptors. Binding of the receptors cause sodium ions (Na+) to enter the muscle cell and potassium ions (K+) to exit the cell; this process causes a local depolarization of the muscle cell = end plate potential (EPP).

Detailed explanation-3: -The sodium-potassium pump goes through cycles of shape changes to help maintain a negative membrane potential. In each cycle, three sodium ions exit the cell, while two potassium ions enter the cell. These ions travel against the concentration gradient, so this process requires ATP.