reniinangiotensiinijärjestelmään

The renin-angiotensin system, often abbreviated as RAS and known in Finnish as the rainiini-angiotensiinijärjestelmä, is a crucial hormonal system that regulates blood pressure and fluid balance in the body. It is a complex cascade of enzymatic reactions and hormonal signals that plays a significant role in cardiovascular homeostasis.

The system is initiated when the kidneys, in response to decreased blood pressure or low sodium levels, release an enzyme called renin. Renin then acts on angiotensinogen, a protein produced by the liver, to convert it into angiotensin I. Angiotensin I is a relatively inactive peptide.

Subsequently, angiotensin I is converted to angiotensin II by the enzyme angiotensin-converting enzyme (ACE), which is found primarily in the lungs and blood vessels. Angiotensin II is the main biologically active component of the RAS. It exerts its effects through various mechanisms.

Firstly, angiotensin II is a potent vasoconstrictor, meaning it narrows blood vessels, which directly increases blood pressure. Secondly, it stimulates the adrenal glands to release aldosterone, a hormone that promotes sodium and water retention in the kidneys, further increasing blood volume and pressure. Angiotensin II also influences thirst and the release of antidiuretic hormone (ADH), contributing to fluid balance.

Dysregulation of the renin-angiotensin system is implicated in various diseases, including hypertension (high blood pressure), heart failure, and kidney disease. Consequently, many medications used to treat these conditions, such as ACE inhibitors and angiotensin II receptor blockers (ARBs), target specific components of this vital system to lower blood pressure and improve cardiovascular health.