Gut motility and its control

To aid the digestion and absorption of nutrients, the gastrointestinal (GI) tract uses a carefully coordinated series of muscular contractions. These contractions serve to propel luminal contents through the tract, as well as churning and mixing them with enzymatic secretions to aid digestion. Smooth muscle of the GI tract exhibits fluctuations in its membrane potential that can lead to action potentials and muscle contraction. These fluctuations, known as the basal electrical rhythm, can range from around three to five per minute in the stomach to 20 per minute in the small intestine. They can be influenced by neural and hormonal input and form the basis of most muscular contractions in the GI tract. The pattern of contractions varies in different parts of the tract to serve the distinct functions of each region, for example, the stomach exhibits a reflex relaxation of muscle to accommodate a meal, while in the small intestine, segmental, mixing contractions predominate.