NEET PG Medical – 2018 – Question – 20
Insulin like growth factor is secreted by:
a) Liver
b) Pituitary gland
c) Pancreas
d) Adrenal glands
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Correct Answer – A
Answer: A. Liver
- Growth hormone acts on the liver to form small proteins called “Somatomedins”
- Somatomedins increases bone growth in all aspect
- Effects are similar to insulin, hence referred to as “Insulin-like Growth Factor” (IGF).
Four types available – - Most important is Somatomedin C – Specifically referred to as “Insulin – Growth Factor -1 / IGF – 1”
- Binds to a carrier protein in blood
- Hence, a longer duration of action than growth hormone.
- Half-life – about 20 Hrs (compared to growth hormone – 20 mins)
- Blood concentration of IGF-1 follows the levels of growth hormone.
- Growth effects of GH are mostly attributed to somatomedin (rather than its direct effect on bones & peripheral tissues)
