The hormone aldosterone regulates sodium levels in the blood. When the amount of sodium in the blood decreases, the amount of water entering the body decreases. Blood volume and blood pressure decrease. As a result, the juxtaglomerular sensory cells are stimulated and the renin enzyme is produced. Renin converts the blood plasma protein into the hormone angiotensin. The hormone angiotensin stimulates the secretion of the hormone aldosterone from the adrenal cortex. The hormone aldosterone stimulates the sodium-potassium pump of the renal tubular cells. In this, sodium enters the blood from the distal convoluted tubule and potassium enters the distal convoluted tubule from the blood. Increased sodium in the blood increases water absorption. As a result, blood volume and blood pressure increase.