Explain the Mixing Movement of the Gastrointestinal Tract

This movement helps the intestinal contents to be thoroughly mixed at all times. It is usually caused by the local contractions of small segments of the gut wall. Movements ate modified in different parts of the gastrointestinal tract for performance of respective work. Let us understand the mixing movement Gastric secretion comes into contact with the stored food in the stomach. When the stomach is filled, mixing waves move along the stomach wall approximately once in 20 seconds. Mixing movement by these waves tend to move the gastric secretions and the food gradually towards the antral part of the stomach. On entering the antrum, the waves become stronger.

The food and gastric secretions become progressively mixed with a greater degree of fluidity. In the small intestine, rhythmic contractions proceed at a rate of 11 to 12 per minute when the chyme enters the duodenum. In this way, there is a progressive mixing of solid food particles with the secretions fiom the small intestine. Mixing movements also occur in the large intestine. Contractions are called haustral contractions. By this movement, the faecal material is gradually exposed to the surface of the large intestine and the fluid is progressively absorbed. These contractions also help to move the faecal contents of the cecum and-ascending colon into the transverse colon.