Renin is a key hormone involved in the renin-angiotensin-aldosterone system (RAAS), which is responsible for regulating blood pressure in response to changes in blood volume. Renin is secreted primarily by the kidneys to promote the production of the peptide hormone angiotensin in the blood vessels. Subsequently, angiotensin stimulates the release of aldosterone from the adrenal cortex, stimulating sodium retention by the kidneys. Renin acts on its substrate angiotensinogen to yield angiotensin I, which is then converted to angiotensin II by the angiotensin-converting enzyme (ACE). Finally, angiotensin 2 promotes the release of aldosterone by the adrenal cortex, which acts on renal tubules, leading to the reabsorption of sodium and water and the excretion of potassium.
