Question:easy
Insulin-like growth factor (IGF-1, somatomedin C) is secreted mainly by which organ?
Insulin-like growth factor (IGF-1, somatomedin C) is secreted mainly by which organ?
Show Hint
Growth hormone acts on this organ to make somatomedins (IGF-1).
Updated On: Jun 23, 2026
- Liver
- Pituitary gland
- Pancreas
- Adrenal glands
Show Solution
The Correct Option is A
Solution and Explanation
Step 1: Trace the growth-hormone signaling chain. The anterior pituitary releases GH, but GH largely works by inducing a second messenger hormone in a target organ.
Step 2: That target is the hepatocyte. GH binding to the liver drives synthesis and release of the somatomedin family of peptides, whose insulin-mimicking activity earns them the name insulin-like growth factors.
Step 3: Somatomedin C, or IGF-1, is the dominant member and is poured into the blood mainly from the liver. Bound to a plasma carrier protein, it persists for roughly $20$ hours versus about $20$ minutes for GH, and its concentration tracks GH output, so most of GH's bone-growth effect is actually delivered through hepatic IGF-1.
Step 4: Knock out the wrong organs: the pituitary makes GH, the pancreas makes insulin and glucagon, and the adrenals make steroids and catecholamines. The liver is the answer. \[\boxed{\text{Liver}}\]
Step 2: That target is the hepatocyte. GH binding to the liver drives synthesis and release of the somatomedin family of peptides, whose insulin-mimicking activity earns them the name insulin-like growth factors.
Step 3: Somatomedin C, or IGF-1, is the dominant member and is poured into the blood mainly from the liver. Bound to a plasma carrier protein, it persists for roughly $20$ hours versus about $20$ minutes for GH, and its concentration tracks GH output, so most of GH's bone-growth effect is actually delivered through hepatic IGF-1.
Step 4: Knock out the wrong organs: the pituitary makes GH, the pancreas makes insulin and glucagon, and the adrenals make steroids and catecholamines. The liver is the answer. \[\boxed{\text{Liver}}\]
Was this answer helpful?
0
