Which electrolyte imbalance is most closely linked with changes in electrical polarization when potassium levels are abnormal?

Which electrolyte imbalance is most closely linked with changes in electrical polarization when potassium levels are abnormal?

• A. Sodium imbalance
• B. Potassium imbalance
• C. Calcium imbalance
• D. Magnesium imbalance

Answer: (B)

Potassium determines the resting membrane potential, which is the electrical polarization of a cell at rest. Cell membranes are much more permeable to potassium than to other ions, so the potassium gradient across the membrane largely sets how negative the inside of the cell is. When potassium levels outside the cell are high (hyperkalemia), the gradient across the membrane is reduced, the resting potential becomes less negative (a depolarization), and cells are closer to the threshold for firing—yet extreme changes can inactivate sodium channels and disrupt conduction. When potassium levels outside are low (hypokalemia), the gradient increases, the resting potential becomes more negative (hyperpolarization), and excitability drops, slowing conduction. Because these polarization changes arise directly from shifts in the potassium gradient, the electrolyte imbalance most closely linked with changes in electrical polarization when potassium is abnormal is the potassium imbalance itself. Other electrolytes influence excitability too, but they do so less directly as the sole determinant of resting polarization.

Potassium determines the resting membrane potential, which is the electrical polarization of a cell at rest. Cell membranes are much more permeable to potassium than to other ions, so the potassium gradient across the membrane largely sets how negative the inside of the cell is. When potassium levels outside the cell are high (hyperkalemia), the gradient across the membrane is reduced, the resting potential becomes less negative (a depolarization), and cells are closer to the threshold for firing—yet extreme changes can inactivate sodium channels and disrupt conduction. When potassium levels outside are low (hypokalemia), the gradient increases, the resting potential becomes more negative (hyperpolarization), and excitability drops, slowing conduction. Because these polarization changes arise directly from shifts in the potassium gradient, the electrolyte imbalance most closely linked with changes in electrical polarization when potassium is abnormal is the potassium imbalance itself. Other electrolytes influence excitability too, but they do so less directly as the sole determinant of resting polarization.