renin - angiotensin system
Renin is a proteolytic enzyme produced by the juxtaglomerular apparatus that converts angiotensinogen in the blood to angiotensin I. Renin release is under the control of a number of factors including blood pressure and volume, and urinary composition. For example, its release is suppressed by sodium and water overload as can occur in primary hyperaldosteronism.
Angiotensin I is converted by angiotensin converting enzyme in the lung to angiotensin II. Angiotensin II then stimulates the adrenal cortex to produce aldosterone. It is also a potent peripheral vasoconstrictor. Aldosterone causes reabsorption of sodium and water from the urine in exchange for potassium and hydrogen ions by activating a pump in distal renal tubule.
Last reviewed 07/2021