Renin is a hormone produced by the kidneys that regulates blood pressure in response to changes in blood volume

  • When an individual is dehydrated, water levels in the blood plasma decrease – leading to lower blood pressure
  • Renin is released from the kidney in response to low blood pressure and increases water reabsorption to raise blood volume

Renin is released from the juxtaglomerular apparatus (JGA) when the kidneys detect a drop in blood pressure

  • Renin converts angiotensinogen (released from the liver) into angiotensin I
  • In the lungs, angiotensin converting enzyme (ACE) converts angiotensin I into angiotensin II
  • Angiotensin II causes vasoconstriction, which functions to increase blood pressure by reducing the diameter of blood vessels
  • Angiotensin II also triggers the adrenal glands to release the hormone aldosterone
  • Aldosterone stimulates sodium uptake in the distal convoluted tubules
  • With more sodium reabsorbed into the bloodstream, more water is reabsorbed from the collecting ducts via osmosis
  • This functions to raise blood volume and hence increases blood pressure

Renin-Angiotensin System