Which process in the small intestine is responsible for rhythmic mixing of chyme with enzymes?

Which process in the small intestine is responsible for rhythmic mixing of chyme with enzymes?

• A. Propulsion
• B. Segmentation
• C. Peristalsis
• D. Absorption

Answer: (B)

Segmentation is the rhythmic, local contraction of the circular smooth muscle in the small intestine that chops and mixes the chyme. These alternating contractions create pockets of chyme that are repeatedly turned over, which increases contact with digestive enzymes, bile, and the mucosal surface. This mixing is essential for enzymes to act on nutrients and for the resulting digestion products to be efficiently absorbed. In contrast, propulsion moves contents along the gut via wave-like contractions (peristalsis), which is about moving chyme forward rather than thoroughly mixing it. Absorption is the uptake of nutrients after digestion, not the mixing action itself.

Segmentation is the rhythmic, local contraction of the circular smooth muscle in the small intestine that chops and mixes the chyme. These alternating contractions create pockets of chyme that are repeatedly turned over, which increases contact with digestive enzymes, bile, and the mucosal surface. This mixing is essential for enzymes to act on nutrients and for the resulting digestion products to be efficiently absorbed.

In contrast, propulsion moves contents along the gut via wave-like contractions (peristalsis), which is about moving chyme forward rather than thoroughly mixing it. Absorption is the uptake of nutrients after digestion, not the mixing action itself.