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

Circular and longitudinal muscles in the alimentary canal contract rhythmically to move the partially digested food mass along in a wave-like action