Which mineral helps maintain fluid balance and supports muscle contraction and nerve impulse transmission?

• A. Sodium
• B. Chloride
• C. Potassium
• D. Calcium

Answer: (A)

Sodium is the mineral that maintains fluid balance and supports muscle contraction and nerve impulse transmission. It helps regulate extracellular fluid volume and osmolality, keeping water distribution in the body's compartments stable. For signaling, nerves and muscles rely on sodium to generate and propagate electrical impulses: when sodium channels open, Na+ rushes into the cell, triggering depolarization that carries the signal along nerves and initiates muscle contraction. Calcium also plays a role in the contraction process itself, and potassium helps reset the cell after an impulse, but sodium’s primary link to both fluid balance and the electrical signals that coordinate muscles and nerves makes it the best fit for this description.