What is the function of Aldosterone?

What is the function of Aldosterone?

• A. Increases excretion of sodium
• B. Increases absorption of sodium, prompting reabsorption of water.
• C. Decreases potassium excretion
• D. Directly increases filtration rate

Answer: (B)

Aldosterone regulates sodium and water balance by acting on the distal parts of the kidney nephron. It increases sodium reabsorption by upregulating epithelial sodium channels and the Na+/K+-ATPase pumps in principal cells, pulling more Na+ from the tubular lumen back into the blood. Since water follows sodium osmotically, this also promotes water reabsorption and helps expand extracellular fluid volume. At the same time, the increased Na+ reabsorption drives potassium secretion into the tubule, increasing potassium excretion. It does not directly raise the glomerular filtration rate. So the primary effect is increasing sodium absorption, which promotes water reabsorption.

Aldosterone regulates sodium and water balance by acting on the distal parts of the kidney nephron. It increases sodium reabsorption by upregulating epithelial sodium channels and the Na+/K+-ATPase pumps in principal cells, pulling more Na+ from the tubular lumen back into the blood. Since water follows sodium osmotically, this also promotes water reabsorption and helps expand extracellular fluid volume. At the same time, the increased Na+ reabsorption drives potassium secretion into the tubule, increasing potassium excretion. It does not directly raise the glomerular filtration rate. So the primary effect is increasing sodium absorption, which promotes water reabsorption.