Question

Where is angiotensinogen secreted from in the human body?

• A. Kidney
• B. Pancreas
• C. Liver
• D. Spleen

Hint:

Angiotensinogen is produced in the liver, while renin is released from the kidneys. Together they initiate the renin–angiotensin system that regulates blood pressure.

Answer 1

The Correct Option is C

Concept: Angiotensinogen is a plasma protein that plays a crucial role in the regulation of blood pressure through the renin–angiotensin system. It acts as the precursor molecule that ultimately leads to the formation of angiotensin II, a powerful vasoconstrictor that increases blood pressure and stimulates the release of aldosterone.

Step 1: Production of angiotensinogen.
Angiotensinogen is synthesized and secreted primarily by hepatocytes, which are the functional cells of the liver. Once produced, it is released into the bloodstream.

Step 2: Role in the renin–angiotensin pathway.
When blood pressure falls, the kidneys release the enzyme renin. Renin converts circulating angiotensinogen into angiotensin I. \[ \text{Angiotensinogen} \xrightarrow{\text{Renin}} \text{Angiotensin I} \] Angiotensin I is then converted into angiotensin II by angiotensin-converting enzyme (ACE).

Step 3: Physiological effect.
Angiotensin II causes vasoconstriction and stimulates aldosterone secretion, which helps increase blood pressure and maintain fluid balance.