At rest, the membrane potential is nearly the equilibrium potential for potassium. Why is potassium able to diffuse easily in and out of cells?
A) Because potassium has a greater concentration in the intracellular fluid (ICF)
B) Because sodium has a greater concentration in the extracellular fluid (ECF)
C) Because the resting plasma membrane is more permeable to potassium
D) Because there is an excess of anions inside the cell

Question

Quizplus · Accepted Answer

The resting membrane potential is determined mainly by the concentration gradients of potassium and sodium ions across the cell membrane and the permeability of the membrane to these ions. The resting membrane potential is closest to the equilibrium potential for potassium because the plasma membrane is more permeable to potassium ions than to sodium ions. This is due to the presence of more potassium leak channels than sodium leak channels, which allows potassium to diffuse easily in and out of cells.

At Rest, the Membrane Potential Is Nearly the Equilibrium Potential