The Renin Angiotensin System (RAS) is a hormone system that plays a crucial role in regulating the body’s blood pressure, fluid balance, and electrolyte balance. The RAS is activated when there is a decrease in blood flow to the kidneys, leading to the release of an enzyme called renin from the kidneys. Renin then acts on a protein called angiotensinogen, which is produced in the liver, to form angiotensin I. Angiotensin I is then converted into angiotensin II by the action of the angiotensin-converting enzyme (ACE) which is present in the lungs. Angiotensin II is a potent vasoconstrictor, which means it narrows blood vessels, leading to an increase in blood pressure. It also stimulates the release of aldosterone, a hormone that regulates salt and water balance in the body. Overall, the RAS is an important system for maintaining blood pressure, fluid balance, and electrolyte balance in the body.