Peristalsis (Edexcel IGCSE Biology: Double Science)

• Peristalsis is a mechanism that helps moves food along the alimentary canal
• Firstly, muscles in the walls of the oesophagus create waves of contractions which force the bolus along
• Once the bolus has reached the stomach, it is churned into a less solid form, called chyme, which continues on to the small intestine
• Peristalsis is controlled by circular and longitudinal muscles
  • Circular muscles contract to reduce the diameter of the lumen of the oesophagus or small intestine
  • Longitudinal muscles contract to reduce the length of that section the oesophagus or the small intestine

• Mucus is produced to continually lubricate the food mass and reduce friction
• Dietary fibre provides the roughage required for the muscles to push against during peristalsis

Muscles in the alimentary canal contract rhythmically to move the partially digested food along in a wave-like action