The digestive system (overview)

The food we eat comes in the form of raw and cooked vegetables, fruits, grains, bread, eggs, meat and milk products, or, in the worse cases, starches, sugars, food colorings and artificial flavors. None of these things can be directly absorbed by the body and turned into energy. In order for the body to be able to use the food as nourishment, it needs to be processed and broken down into small molecules, so the blood can carry the nutrients, vitamins and minerals to the cells throughout the body. Digestion is the complex mechanical and chemical modification process that turns a meal into useful energy and nourishment. The digestive system (or gastrointestinal tract) is a long chain of hollow organs, muscles and glands, approximately 9 meters in total length; it starts at the mouth, where the food and drink enter the body, and ends at the anus, where the waste leaves the body. The main stops along the digestive tract are: the mouth, the pharynx, the esophagus, the stomach, the small intestine, the large intestine, and the anus. There are also other organs that are not part of the digestive system but are necessary for digestion: the liver, gallbladder and the pancreas.