Ease Into Prep with an MCAT^® Question of the Day

The sodium-potassium pump maintains a negative membrane potential, to prepare the cell membrane for an action potential by actively pumping out more cations than it brings in. In other words, the sodium potassium pump maintains the membrane resting potential. Choose (D).

Expert Approach:
This stem invites a prediction: I know that the sodium-potassium pump plays a vital role in maintaining the ion gradients that set up the resting potential, so I'm looking for an answer that reflects that; (D) does, and is correct.The process of elimination could also be a relatively efficient way to get through this question. Options (A), (B), and (C) are all phases of the action potential, and while the sodium-potassium pump creates the ion gradients that underlie both the resting potential and the action potential, it doesn't play a direct role in the generation or propagation of the action potential itself. That fact neatly eliminates all three of the incorrect choices!

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