Final answer:
ADH increases peripheral vascular resistance by constricting arterioles, which raises blood pressure and reduces blood flow to extremities. It also promotes water reabsorption in the kidneys by activating aquaporin channels, which further increases blood volume and pressure.
Step-by-step explanation:
Antidiuretic hormone (ADH) plays a crucial role in regulating peripheral vascular resistance to maintain blood pressure. One of the ways ADH increases peripheral vascular resistance is by causing the constriction of arterioles in the peripheral circulation, which decreases blood flow to extremities and increases blood supply to vital organs. This vasoconstriction, which is a result of ADH acting as a vasoconstrictor, leads to an increase in blood pressure.
Additionally, ADH activates the movement of aquaporin water channel proteins to the apical surface of renal collecting tubule epithelial cells, increasing the permeability of these cells to water. This means more water is reabsorbed from the urine back into the bloodstream, which contributes to an increase in blood volume and, consequently, blood pressure.
Furthermore, ADH release is triggered by blood volume decreases of 5-10 percent, which induce immediate vasoconstriction to elevate blood pressure. In parallel, ADH and aldosterone work together to increase blood volume and pressure by facilitating water reabsorption in the kidneys, with aldosterone specifically increasing sodium reabsorption, which pulls water back into the blood due to osmotic forces.