What is the primary effect of aldosterone?

Aldosterone is a hormone produced by the adrenal cortex, and its primary function is to regulate sodium and potassium levels in the body. The main action of aldosterone is to increase sodium reabsorption in the distal tubules and collecting ducts of the nephron in the kidneys. This mechanism helps to retain sodium, which leads to an increase in water reabsorption due to osmosis, ultimately resulting in enhanced blood volume and blood pressure.

By increasing sodium reabsorption, aldosterone also indirectly affects potassium levels. Specifically, as sodium is reabsorbed, potassium is secreted into the tubular fluid for excretion. Thus, while aldosterone does support a certain degree of potassium excretion, its primary role lies in the retention of sodium.

This regulation of sodium has profound physiological implications, impacting fluid balance, blood pressure, and overall electrolyte homeostasis in the body. The other options do not accurately reflect the primary physiological action of aldosterone, which consistently emphasizes its role in sodium management.