The electrochemical gradient of a given ion determines the movement of that ion across a cell membrane.Based on your knowledge of the normal intra- and extracellular concentrations of Na⁺ and K⁺ ions across a resting membrane, what would you expect to happen when both Na⁺ and K⁺ voltage-gated channels were opened in response to an action potential? A) Na⁺ and K⁺ would both move out of the cell. B) Na⁺ would move into the cell, whereas K⁺ would move out of the cell. C) Na⁺ would move out of the cell, whereas K⁺ would move into the cell. D) Na⁺ and K⁺ would both move into the cell. E) Na⁺ would move out of the cell but K⁺ flow would cease.

Question

Quizplus · Accepted Answer

Normally, the concentration of Na+ is higher outside the cell, and the concentration of K+ is higher inside the cell. When voltage-gated channels open during an action potential, Na+ moves into the cell due to its electrochemical gradient, and K+ moves out of the cell, also following its electrochemical gradient.

The Electrochemical Gradient of a Given Ion Determines the Movement