The second peristaltic wave is initiated by what?

• A. Continued dilation and pressure from bolus movement
• B. Immediate contraction of all esophageal muscles
• C. Swallowing of saliva only
• D. Random neural noise

Answer: (A)

Secondary peristalsis is a reflex that kicks in when the esophagus remains distended by a bolus. The stretching of the esophageal wall activates stretch receptors, which trigger a new, coordinated wave of contraction to push any remaining material down toward the stomach. That’s why continued dilation and pressure from the bolus itself initiates the second peristaltic wave.

This isn’t a simultaneous, all-at-once contraction of the entire esophagus, so that option doesn’t fit. Swallowing saliva alone mainly triggers the initial primary peristaltic wave, not the secondary one. And random neural noise wouldn’t produce a purposeful, coordinated motor event like secondary peristalsis.