(rē'nin-an'jē-ō-ten'sin al-dos'tĕr-ōn sis'tĕm)
Hormones, renin, angiotensin, and aldosterone work together to regulate blood pressure. A sustained fall in blood pressure causes the kidney to release renin. This is converted to angiotensin in the circulation. Angiotensin then raises blood pressure directly by arteriolar constriction and stimulates the suprarenal glands to produce aldosterone that promotes sodium and water retention by kidney, such that blood volume and blood pressure increase.