What is the role of peristalsis in digestion?

• A. It emulsifies fats
• B. It propels content through the digestive tract
• C. It secretes digestive enzymes
• D. It absorbs nutrients

Answer: (B)

Peristalsis is the coordinated, wave-like contraction of the smooth muscle in the walls of the digestive tract that moves contents forward. As a bolus enters a segment, the circular muscles behind it contract to push it ahead, while the longitudinal muscles ahead shorten the tract, producing a forward propulsion that carries material from the esophagus through the stomach and into the intestines. This propulsion is essential for digestion and transit, helping ensure the food reaches areas where enzymes can act and where nutrients can be absorbed.

This differs from other motility patterns that mix contents rather than move them along, such as segmentation. Emulsifying fats, secreting digestive enzymes, and absorbing nutrients involve other processes and parts of the GI system (bile for emulsification; glands and pancreas for enzymes; enterocytes in the small intestine for absorption).