Final answer:
Angiotensin II directly stimulates an increase in thirst in the hypothalamus, leading to higher fluid intake, which in turn raises blood volume and blood pressure.
Step-by-step explanation:
Angiotensin II is a potent vasoconstrictor that increases blood pressure and plays a crucial role in fluid balance. Among its many actions, angiotensin II acts directly in the hypothalamus to stimulate an increase in thirst, which leads an individual to consume more fluids, contributing to an increased blood volume and blood pressure. It also stimulates the release of other hormones that affect fluid balance, such as ADH (antidiuretic hormone) and aldosterone, which increase water reabsorption in the kidneys and sodium retention, respectively.