Which hormone causes increased food intake-
**Core Concept**
The question is testing the student's knowledge of the hormonal regulation of appetite. The hormone in question is a peptide hormone produced by the hypothalamus that stimulates appetite and increases food intake.
**Why the Correct Answer is Right**
The correct hormone, **Ghrelin**, is produced by the epithelial cells of the stomach and functions as a neuropeptide in the hypothalamus. Ghrelin binds to its receptor, GHSR, in the arcuate nucleus of the hypothalamus, stimulating the expression of neuropeptide Y (NPY) and agouti-related peptide (AgRP), which are orexigenic neuropeptides that promote food intake. Ghrelin's action is opposite to that of leptin, which inhibits appetite.
**Why Each Wrong Option is Incorrect**
**Option A:** Insulin - Insulin is a hormone produced by the pancreas that regulates blood glucose levels by facilitating glucose uptake in cells. While insulin can stimulate food intake indirectly by lowering blood glucose levels, it is not the primary hormone responsible for increased food intake.
**Option B:** Glucagon - Glucagon is a hormone produced by the pancreas that raises blood glucose levels by stimulating glycogenolysis and gluconeogenesis. Glucagon does not stimulate food intake.
**Option C:** Leptin - Leptin is a hormone produced by adipose tissue that inhibits appetite and increases energy expenditure. Leptin's action is opposite to that of ghrelin.
**Clinical Pearl / High-Yield Fact**
Ghrelin levels typically peak before meals and decrease after eating, providing a physiological basis for the concept of "hunger pangs."
**Correct Answer:**. Ghrelin