AEMCA Practice Exam

What role does sodium have in the function of aldosterone?

1. It stimulates the production of ADH.

2. It promotes sodium excretion by the kidneys.

3. It facilitates sodium reabsorption in the renal tubules.

4. It has no role related to aldosterone.

The correct answer is: It facilitates sodium reabsorption in the renal tubules.

Sodium plays a crucial role in the function of aldosterone primarily by facilitating sodium reabsorption in the renal tubules. Aldosterone, a hormone produced by the adrenal glands, acts on the distal convoluted tubules and the collecting ducts in the kidneys to promote the reabsorption of sodium from the filtrate back into the bloodstream. This action helps regulate blood pressure and fluid balance in the body. By promoting sodium reabsorption, aldosterone indirectly influences water retention, as water follows sodium osmotically, leading to an increase in blood volume and, consequently, blood pressure. This mechanism is a key part of the body's overall strategy to maintain homeostasis, particularly in response to conditions such as dehydration or low blood pressure, where increased sodium (and thus water) retention would be beneficial. The other options do not accurately reflect the relationship between sodium and aldosterone; for instance, while ADH (antidiuretic hormone) also influences water balance, it does not directly relate to sodium's role with aldosterone, and promoting sodium excretion is contrary to the action of aldosterone, which seeks to retain sodium instead.