reninaangiotenzynaaldosteron

The renin-angiotensin-aldosterone system, often abbreviated as RAAS, is a crucial hormonal cascade that plays a significant role in regulating blood pressure and fluid balance in the body. This intricate system is primarily activated when blood pressure drops or when there is a decrease in sodium levels reaching the kidneys.

The process begins in the kidneys, which release an enzyme called renin. Renin then acts on a protein produced by the liver called angiotensinogen, converting it into angiotensin I. This intermediate substance is further processed by an enzyme, predominantly found in the lungs, called angiotensin-converting enzyme (ACE). ACE transforms angiotensin I into angiotensin II.

Angiotensin II is a potent vasoconstrictor, meaning it narrows blood vessels, which directly increases blood pressure. Beyond its immediate effect on blood vessels, angiotensin II also stimulates the adrenal glands to release aldosterone. Aldosterone is a hormone that acts on the kidneys, promoting the reabsorption of sodium and water. This retention of salt and water increases blood volume, which in turn raises blood pressure.

The RAAS is a complex feedback loop. Elevated blood pressure and increased blood volume eventually signal the kidneys to reduce renin release, thus downregulating the system. Dysfunction of the RAAS is implicated in various cardiovascular conditions, including hypertension, heart failure, and kidney disease. Medications targeting different components of this system, such as ACE inhibitors and angiotensin receptor blockers (ARBs), are widely used to manage these conditions.