Renin-angiotensin-aldosterone system

The renin-angiotensin-aldosterone system (RAAS) is a hormone system that regulates blood pressure and fluid balance [1]. When blood pressure or blood volume drops, juxtaglomerular cells in the kidneys secrete renin into the bloodstream [2]. Renin cleaves angiotensinogen produced by the liver into angiotensin I [1][3]. Angiotensin converting enzyme (ACE) then converts angiotensin I into angiotensin II [4]. Angiotensin II has several effects including vasoconstriction, increased thirst, and stimulation of aldosterone release from the adrenal cortex [1][5]. Aldosterone increases sodium and water reabsorption in the kidneys to increase blood volume and pressure [3][6]. This negative feedback loop restores homeostasis after perturbations like dehydration or blood loss [2][4]. Dysregulation of the RAAS can contribute to hypertension and other cardiovascular diseases [5][6].