So nothing can go backwards and get stuck.
...
It also maintains the diffusion gradient if food is moving in one direction so the products of digestion are absorbed faster.
The digestive system has smooth muscle through out it, and they help move the food.
Digestive
Muscle motion in your digestive system called Peristalsis helps the food to travel through your digestive system.
muscles
"peristalsis"
Yes, by peristaltic movement.
Aerial A Harris
SMOOTH muscle
peristalsis
Yes, the muscles squeeze the food through the digestive system :)
peristalsis
peristalsis is a muscle that helps food to get through the oesphagus