Enzymes in the saliva begin the process of digestion. Most of the chemical breakdown of food happens in the stomach and small intestine. Enzymes are secreted and mixed with the food. The enzymes break down large molecules into smaller ones so the food becomes soluble. Acid in the stomach helps with this breakdown.
Food passes out of the stomach into the gut.
The gut is a tube about 10 metres long. Food is pushed along it by the gut muscles. 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.