Mixing movements of the small intestine are also known as what?

• A. Peristaltic waves
• B. Migrating motor complex
• C. Gastrointestinal reflexes
• D. The segmental contractions

Answer: (D)

Mixing movements in the small intestine are produced by segmental contractions of the circular muscle layer, known as segmentation. These localized contractions divide the chyme into smaller segments and alternate with relaxation, increasing contact with the absorptive surface and enabling enzymes to act on nutrients. This contrasts with peristaltic waves, which propel contents forward through coordinated contractions of circular and longitudinal muscles. The migrating motor complex is a fasting pattern that sweeps residual contents out, not a mixing action, and general gastrointestinal reflexes describe regulatory pathways rather than a specific mixing movement. So the smooth, rhythmic segmental contractions are the mixing mechanism.