And that's exactly why ADH is also known as vastopressin, because it presses on those vessels and that's why we have vassal constriction. So once again, ADH is released when blood osmolarity increases. That means our solid concentration increases and our volume, amount of water decreases in the blood. So ADH affects the permeability of the collecting dusts in our kidneys to water. It increases the amount of water that is absorbed back into the blood vessels. And that means it decreases the amount of water that is released in the urine.