2.28 understand how food is moved through the gut by peristalsis

What is peristalsis?
- The contractions of two sets of muscles in the walls of the oesophagus. One set runs along the oesophagus, while the other set circles it. Their wave-like contractions create a squeezing action, moving down the oesophagus.
- These wavelike contractions push the food down the oesophagus.

The two muscles are called circular muscles and longitudinal muscles. Circular muscles contract to change the radius of the oesophagus, and longitudinal muscles contract to change the length of the oesophagus.



Purpose: 
1. push food down without force of gravity
2. so large food boluses don't get stuck