What do physiologically normal kidneys reabsorb in response to aldosterone?

Aldosterone, a steroid hormone produced by the adrenal glands, plays a crucial role in regulating electrolyte balance and fluid volume in the body. When aldosterone is secreted, it promotes the reabsorption of sodium from the renal tubules back into the bloodstream. This mechanism occurs primarily in the distal convoluted tubule and the collecting ducts of the nephron.

As sodium is reabsorbed, water typically follows osmotically, leading to an increase in overall fluid retention. This effect helps to maintain blood pressure and overall fluid balance in the body. Therefore, in a physiologically normal state, the kidneys respond to aldosterone by reabsorbing both sodium and water.

Although potassium is indeed affected by aldosterone (it is often secreted into the urine as sodium is reabsorbed), it is not reabsorbed in response to aldosterone. The hormone does not primarily drive the reabsorption of calcium or chloride either. Thus, the correct answer centers on the reabsorption of sodium and water, aligning with the primary physiological functions of aldosterone.