AP BIOLOGY

Detailed explanation-1: -ADH makes the collecting ducts more permeable to water so that more water is reabsorbed. As a result, a small volume of concentrated urine is produced. ADH acts on aquaporin-2, a membrane protein that forms gated water channels in the wall of the collecting ducts.

Detailed explanation-2: -ADH increases the water permeability of the late distal tubule (or connecting duct) and all parts of the collecting duct. It also increases the urea permeability of the inner medullary collecting duct.

Detailed explanation-3: -ADH increases the permeability to water of the distal convoluted tubule and collecting duct, which are normally impermeable to water. This effect causes increased water reabsorption and retention and decreases the volume of urine produced relative to its ion content.

Detailed explanation-4: -Vasopressin increases the water permeability of the renal collecting duct cells, allowing more water to be reabsorbed from collecting duct urine to blood.