The response begins by secretion of the hormone renin. Renin splits angiotensinogen producing angiotensin I. A converting enzyme in the liver and lungs changes angiotensin I into angiotensin II. Angiotensin II also stimulates the secretion of aldosterone by the adrenal cortex. This in turn, increases sodium and subsequent water reabsorption in the distal tubules of the kidney to maintain intravascular volume and decreased urine excretion.