Think of the digestive system as one larger tube that goes from your mouth to your anus. Food enters the mouth, and immediately chemicals in the saliva start to break down the food, as well as any chewing, or mastication that you do. Then you swallow it sending it down the esophagus into the stomach. The food is then subjected to pressures and digestive chemicals to break it down further. Then it moves into the small intestine where the small molecules of nutrients absorb through the intestinal walls into the blood stream so that cells can use it for energy. Most foods are turned into glucose, or blood sugar for this purpose. Any waste, such as roughage or plant fibers, excess liquids and other material mixes with wastes sent to the large intestine to become feces and is sent to the colon.