Angiotensinogen is a protein produced by the liver that plays a crucial role in regulating blood pressure. It is the precursor to angiotensin I, which is converted into angiotensin II by the enzyme renin. This conversion is part of the renin-angiotensin system, a key mechanism in maintaining cardiovascular health. Angiotensin II has several important functions, including constricting blood vessels and stimulating the release of aldosterone, a hormone that helps control sodium and water balance. By influencing these processes, angiotensinogen indirectly affects blood volume and pressure, making it vital for overall circulatory function.