Food enters the digestive system through the mouth. This process is called ingestion. Once in the mouth, the food is chewed to form a ball of food called a bolus. This passes down the oesophagus and into the stomach.


Food is moved through the digestive system by a process called peristalsis. Two sets of muscles in the gut wall are involved:

  • circular muscles - which reduce the diameter of the gut when they contract
  • longitudinal muscles - which reduce the length of the gut when they contract

The muscles work together to produce wave-like contractions. These have a ‘squeezing action’ that pushes the bolus through the gut.

Three images of the oesophagus showing food traveling through by peristalsis.  Circular muscles above the food contract causing a peristaltic wave. Circular muscles surrounding the food are relaxed.Peristalsis continues to move food through the small intestine and the large intestine