Ghrelin, an orexigenic peptide, is secreted primarily by which cells, and how do its plasma levels behave across a meal?

• A Gastric fundus oxyntic cells; levels rise before a meal and fall after it ✓
• B Duodenal K cells; levels rise before a meal and fall after it
• C Gastric fundus oxyntic cells; levels fall before a meal and rise after it
• D Colonic L cells; levels remain constant throughout the meal

Explanation

Ghrelin is produced mainly by X/C-like endocrine cells of the gastric fundus. Plasma ghrelin rises before scheduled meals, signalling hunger to hypothalamic NPY/AgRP neurons, and falls within about an hour of food intake. It is the only known gut hormone that stimulates appetite. GLP-1 comes from colonic L cells and GIP from duodenal K cells, both incretins that suppress appetite and stimulate insulin, making them structurally tempting distractors here.

Reference: Ganong's Review of Medical Physiology, 26th ed.

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