Final answer:
Increased angiotensin II during hypovolemic shock leads to aldosterone release, which causes sodium and water retention, thus increasing blood volume and pressure.
Step-by-step explanation:
When the body is compensating for hypovolemic shock and there is increased angiotensin II, the physiological change that occurs is the release of aldosterone, resulting in sodium and water reabsorption and an increase in blood volume and pressure. Angiotensin II is a potent vasoconstrictor, and it also stimulates the release of antidiuretic hormone (ADH), which promotes water retention by inserting aquaporin water channels into cell membranes. These mechanisms collectively help in raising blood pressure during hypovolemic states.