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Physiology · Gastrointestinal: ileal brake
Sample itemWhen unabsorbed fat reaches the distal ileum, gastric emptying and small bowel transit slow down. Which gut peptides mediate this feedback?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
A. Peptide YY and GLP-1
Nutrients in the distal ileum release peptide YY and GLP-1 from L cells. These peptides slow gastric emptying and intestinal transit, and give a sense of satiety, a response called the ileal brake. It allows more time for digestion and absorption of an unabsorbed load.
Option by option
A. Peptide YY and GLP-1 (correct)
Correct. L-cell peptides PYY and GLP-1 mediate the ileal brake.
B. Secretin and VIP
Secretin and VIP stimulate pancreatic bicarbonate and intestinal secretion and do not mediate the ileal brake.
C. Motilin and ghrelin
Motilin and ghrelin stimulate motility and are released in the fasting state.
D. Gastrin and histamine
Gastrin and histamine stimulate gastric acid secretion.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
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