Which statement about peristalsis and segmentation is true?

• A. They occur only in the stomach
• B. They are the same process
• C. Peristalsis moves contents along while segmentation churns and mixes contents with secretions
• D. Segmentation moves more quickly than peristalsis

Answer: (C)

The main idea here is that the digestive tract uses two distinct motor patterns to handle contents: one that propels material forward and another that thoroughly mixes it. Peristalsis is a sequence of coordinated, wave-like contractions of the circular and longitudinal smooth muscles that push the contents along the tract. This mechanism moves food from one end of a segment to the other, helping to transport it toward the stomach or onward through the intestines.

Segmentation, on the other hand, involves rhythmic, non-propulsive contractions that churn and divide the luminal contents into smaller portions. This action maximizes contact with digestive secretions and the absorptive surfaces by mixing chyme with bile, pancreatic enzymes, and other secretions, especially in the small intestine.

That combination—peristalsis moving contents along and segmentation mixing them with secretions—matches the true statement. It’s not correct to say these processes occur only in the stomach, since peristaltic waves occur along the GI tract and segmentation is a hallmark of small intestinal function. They are not the same process; they serve different purposes. And segmentation is generally slower and focused on mixing rather than net forward movement, unlike peristalsis.