The hormone ADH functions to promote water reabsorption through what?

The hormone ADH (antidiuretic hormone), also known as vasopressin, promotes water reabsorption primarily through its action on the kidneys. It increases the permeability of the renal collecting ducts to water by stimulating the insertion of aquaporin-2 water channels into the cell membranes of the duct cells. This process allows more water to be reabsorbed back into the bloodstream, reducing urine output and helping to maintain body fluid balance.