Which organ secretes angiotensinogen?

The liver is responsible for the production and secretion of angiotensinogen, which is a precursor to angiotensin. Angiotensinogen is a plasma protein that is synthesized and released by the liver into the bloodstream. When blood pressure drops or when there is a decrease in blood flow to the kidneys, the kidneys release an enzyme called renin. Renin cleaves angiotensinogen to form angiotensin I, which is then converted to angiotensin II primarily by the action of angiotensin-converting enzyme (ACE) in the lungs.

Angiotensin II plays a crucial role in the regulation of blood pressure and fluid balance, making it a significant component of the renin-angiotensin-aldosterone system (RAAS). By understanding this process, it's clear why the liver is identified as the organ that secretes angiotensinogen, illustrating its central role in this vital physiological regulation.