RAAS Pathway

The Renin-Angiotensin-Aldosterone System (RAAS) also known as the Renin-Angiotensin System (RAS) is a multi-hormonal system that coordinates a variety of physiological processes for proper regulation of blood volume and pressure.

RAAS regulates sodium and water absorption in the kidney, thus directly having an impact on systemic blood pressure.

Typically, RAAS is activated when there is a drop in blood pressure (reduced blood volume) to increase water and electrolyte reabsorption in the kidney; which compensates for the drop in blood volume, thus increasing blood pressure.

When renin is released into the blood, it acts upon a circulating substrate, angiotensinogen, that undergoes proteolytic cleavage to form the decapeptide angiotensin I. Vascular endothelium, particularly in the lungs, has an enzyme, angiotensin converting enzyme (ACE), that cleaves off two amino acids to form the octapeptide, angiotensin II (AII), although many other tissues in the body (heart, brain, vascular) also can form AII.