What does aldosterone do?

What does aldosterone do?

• A. Increases water reabsorption independently of sodium.
• B. Increases absorption of sodium, prompting reabsorption of water.
• C. Decreases sodium reabsorption
• D. Increases potassium excretion

Answer: (B)

Aldosterone raises sodium reabsorption in the distal nephron (and collecting ducts). By increasing sodium reabsorption, it creates an osmotic pull for water to follow, so water reabsorption increases as well. This combination raises extracellular fluid volume and helps raise blood pressure. Aldosterone also promotes potassium excretion to balance the added Na+ reabsorption, but the key effect tying everything together is that sodium reabsorption drives subsequent water reabsorption. The statement that best reflects this is that it increases absorption of sodium, prompting reabsorption of water.

Aldosterone raises sodium reabsorption in the distal nephron (and collecting ducts). By increasing sodium reabsorption, it creates an osmotic pull for water to follow, so water reabsorption increases as well. This combination raises extracellular fluid volume and helps raise blood pressure. Aldosterone also promotes potassium excretion to balance the added Na+ reabsorption, but the key effect tying everything together is that sodium reabsorption drives subsequent water reabsorption. The statement that best reflects this is that it increases absorption of sodium, prompting reabsorption of water.