Circulatory volume regulation

Circulatory volume regulation

Control of the circulatory volume is regulated to a large extent by the renin-angiotensin system. The kidney releases renin upon decreasing plasma sodium levels and decreasing circulatory volume. Renin converts angiotensinogen from the liver to angiotensin I. Angioconverting enzyme from the lungs converts angiotensin I into angiotensin II.


The latter stimulates the cells in the zona glomerulosa to synthesise and secrete aldosterone. This hormone forces the tubular cells in the kidney to reabsorb sodium ions, and as a result, water.

Check the circulation section for more information on the RAAS system and regulation by aldosterone.


I. The adrenal medulla produces noradrenaline and cortisol.

II. Angiotensin II stimulates aldosterone secretion.