Membrane Transport Mechanisms · Physiology

Why is the Na⁺/K⁺-ATPase pump considered electrogenic, and what is a consequence for the membrane potential?

  1. It transports equal charges so no net effect on membrane potential
  2. It pumps more Na⁺ out than K⁺ in, making the interior more negative
  3. It moves more K⁺ out than Na⁺ in, depolarizing the whole cell
  4. It affects only osmotic balance and not the electrical potential
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Correct answer: It pumps more Na⁺ out than K⁺ in, making the interior more negative

The Na⁺/K⁺-ATPase exchanges 3 Na⁺ out for 2 K⁺ in per ATP hydrolyzed, creating a net loss of positive charges from the cell, which helps establish the negative resting membrane potential crucial for many cell functions.

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