Question:
Antegrade peristalsis (descending relaxation ahead of the bolus) is due to which one of the following neurotransmitters?
Antegrade peristalsis (descending relaxation ahead of the bolus) is due to which one of the following neurotransmitters?
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Antegrade movement needs descending relaxation ahead of the bolus - recall its inhibitory transmitter.
Updated On: Jun 23, 2026
- Acetylcholine
- Serotonin
- Substance P
- VIP
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The Correct Option is D
Solution and Explanation
Step 1: Peristalsis is the coordinated motor pattern that moves gut contents in the antegrade (aboral, toward the anus) or retrograde (oral) direction. It has two synchronised limbs around the bolus.
Step 2: Behind the bolus, impulses traveling orad drive ascending contraction; the transmitters here are acetylcholine, substance P and neurokinin A.
Step 3: Ahead of the bolus, impulses traveling caudad drive descending relaxation so the segment can receive the contents; the transmitters here are vasoactive intestinal peptide (VIP), nitric oxide (NO) and PACAP.
Step 4: Forward (antegrade) movement depends on this descending inhibitory relaxation, which is mediated by VIP. Acetylcholine and substance P drive the contractile limb, and serotonin acts as a trigger rather than the relaxing transmitter. Hence the answer is VIP.
Step 2: Behind the bolus, impulses traveling orad drive ascending contraction; the transmitters here are acetylcholine, substance P and neurokinin A.
Step 3: Ahead of the bolus, impulses traveling caudad drive descending relaxation so the segment can receive the contents; the transmitters here are vasoactive intestinal peptide (VIP), nitric oxide (NO) and PACAP.
Step 4: Forward (antegrade) movement depends on this descending inhibitory relaxation, which is mediated by VIP. Acetylcholine and substance P drive the contractile limb, and serotonin acts as a trigger rather than the relaxing transmitter. Hence the answer is VIP.
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