Circular muscles behind the food contract, pushing the food onward. This is called peristalsis . Because some of the food is now soluble, it can pass through the wall of the small intestine and into the bloodstream. This is called absorption . This soluble food can be used by body cells, for energy and growth.
Undigested food moves on inside the gut.
A normal diet contains a lot of water - 5 to 7 litres per day. This is mainly absorbed through the large intestine into the bloodstream. The remaining undigested food has to be got rid of. We have to learn to control this defacation. Digestion means breaking down insoluble food into small soluble molecules which can be absorbed into the bloodstream.