What is the function of renin in the body?

Renin is a crucial enzyme in the renin-angiotensin-aldosterone system (RAAS), which plays a significant role in regulating blood pressure and fluid balance. The primary function of renin is to convert angiotensinogen, a protein produced by the liver, into angiotensin I. This reaction is the initial step in a cascade that ultimately leads to the production of angiotensin II, a potent vasoconstrictor.

Angiotensin II has several key effects, including stimulating the release of aldosterone from the adrenal cortex, which promotes sodium and water reabsorption in the kidneys, leading to increased blood volume and blood pressure. Therefore, while renin itself does not directly stimulate aldosterone release or increase sodium reabsorption, it is essential in producing angiotensin I, which sets off this physiological process.

Understanding the role of renin helps clarify its importance in maintaining homeostasis and managing conditions related to hypertension and fluid imbalance.