Question

question 22
by which mechanism does adh stimulate water reabsorption in the collecting ducts of the kidney?
decreasing sodium pump activity on the basolateral side of the collecting duct cell.
moving aquaporin channels from the interior to the apical cell membrane of the collecting duct cell.
moving sodium channels from the interior to the membrane of the collecting duct cell.
increasing sodium pump activity on the basolateral side of the collecting duct cell.

Explanation:

Antidiuretic hormone (ADH) acts on the collecting ducts of the kidney. Aquaporins are water - channel proteins. When ADH is present, it causes aquaporin channels to move from intracellular vesicles to the apical (luminal) cell membrane of the collecting duct cells. This allows for increased permeability of the collecting duct cells to water, enabling water reabsorption. Decreasing or increasing sodium pump activity on the basolateral side (which is involved in sodium - potassium exchange) is not the direct mechanism for water reabsorption stimulated by ADH. Moving sodium channels (which are more relevant for sodium transport, not directly for water reabsorption in the context of ADH's main water - reabsorbing action) is also incorrect.

Answer:

Moving aquaporin channels from the interior to the apical cell membrane of the collecting duct cell.