Digestion is the process by which food is broken down into smaller pieces so that the body can use them to build and nourish cells and to provide energy. Digestion involves the mixing of food, its movement through the digestive tract (also known as the alimentary canal), and the chemical breakdown of larger molecules into smaller molecules. Every piece of food we eat has to be broken down into smaller nutrients that the body can absorb, which is why it takes hours to fully digest food.
The digestive system is made up of the digestive tract. This consists of a long tube of organs that runs from the mouth to the anus and includes the esophagus, stomach, small intestine, and large intestine, together with the liver, gall bladder, and pancreas, which produce important secretions for digestion that drain into the small intestine. The digestive tract in an adult is about 30 feet long.
