Where does angiotensin I get converted to angiotensin II, and by what enzyme?

Angiotensin I is converted to angiotensin II primarily in the lungs by the enzyme angiotensin-converting enzyme (ACE). This conversion process is a crucial step in the renin-angiotensin-aldosterone system (RAAS), which plays a key role in regulating blood pressure and fluid balance in the body.

Angiotensin I, which is an inactive precursor, is produced in the liver and released into the bloodstream. When it reaches the lungs, ACE acts on angiotensin I, cleaving it to form the active peptide angiotensin II. Angiotensin II has various physiological effects, including vasoconstriction and stimulating aldosterone secretion from the adrenal glands, ultimately leading to increased blood pressure.

The choice highlighting the liver and renin does not accurately describe the site of conversion for angiotensin I; instead, renin is responsible for the initial conversion of angiotensinogen (which is made in the liver) into angiotensin I. The kidneys are involved in the production of renin but do not convert angiotensin I into angiotensin II. The heart does not play a direct role in the conversion process of angiotensin I as well. Thus, the lungs, with the action of