What is the effect of angiotensin II in the body?

Angiotensin II plays a significant role in the regulation of blood pressure and fluid balance within the body. Its primary effect is vasoconstriction, meaning it causes blood vessels to narrow. This process increases the resistance the heart must work against, which consequently raises blood pressure. By constricting blood vessels, angiotensin II enhances the overall perfusion to vital organs, while also stimulating the release of aldosterone and antidiuretic hormone (ADH), both of which contribute to increased blood volume and further elevation of blood pressure.

This mechanism is particularly important in response to blood loss or dehydration, as it helps restore blood pressure to a normal level. While angiotensin II does have other functions, such as influencing thirst and sodium retention through aldosterone, the direct action on blood vessels is predominantly vasoconstriction.