What are the two primary functions of angiotensin II?

Angiotensin II plays crucial roles in the body, primarily related to the regulation of blood pressure and fluid balance. Its two main functions are as a potent vasoconstrictor and a stimulator of aldosterone secretion from the adrenal glands.

As a vasoconstrictor, angiotensin II narrows blood vessels, which increases vascular resistance and raises blood pressure. This is essential in situations where blood pressure needs to be elevated, such as in response to blood loss or dehydration.

In addition to its vasoconstrictive effects, angiotensin II stimulates the secretion of aldosterone, a hormone that promotes sodium and water reabsorption in the kidneys. By enhancing sodium retention, aldosterone increases blood volume, which also contributes to elevating blood pressure.

This dual action of raising blood pressure through both direct vasoconstriction and increasing blood volume is critical for maintaining cardiovascular stability and ensuring adequate perfusion of organs, particularly during stress or hypotensive states.