Gastrointestinal motility: some basic concepts.

The spatial and temporal patterns of phasic contractions in the gastrointestinal tract are regulated by a complex interplay between the myogenic, neural and chemical control mechanisms. These contractions are largely responsible for the mixing and propulsive movements of the gut after a meal. In the fasted state, organized groups of contractions called cyclic motor activity and migrating motor complex keep the upper digestive tract clean of residual food and debris. In addition, the small intestine and the colon generate giant migrating contractions which are several-fold stronger than the postprandial phasic contractions and migrate uninterrupted over long distances. The giant migrating contractions are effective in rapid propulsion. The upper small intestine and the antrum generate retrograde giant contractions that generally precede vomiting.