Which organ is primarily involved in converting angiotensin I to angiotensin II?

The organ primarily responsible for converting angiotensin I to angiotensin II is the lungs. This process occurs mainly in the pulmonary circulation, where angiotensin-converting enzyme (ACE) is abundant. ACE catalyzes the conversion of angiotensin I, an inactive precursor, into angiotensin II, which is a potent vasoconstrictor that plays a critical role in regulating blood pressure and fluid balance in the body.

Angiotensin II has significant physiological effects, including the stimulation of aldosterone secretion from the adrenal glands, which promotes sodium and water reabsorption in the kidneys, ultimately increasing blood volume and blood pressure. This conversion is essential in the renin-angiotensin-aldosterone system (RAAS), which helps maintain homeostasis in response to blood pressure changes.

The liver, while it does produce angiotensinogen (the precursor to angiotensin I), is not involved in the conversion process itself. The kidneys play a role in the production of renin, which initiates the formation of angiotensin I from angiotensinogen, but they do not convert it to angiotensin II. The heart is involved in the overall regulation of blood pressure and fluid balance but does not have a direct