The small intestine main function is food digestion aiding while it transports it from the stomach to the colon. The small intestine is divided in three parts, the duodenum, jejunum and ileum.The duodenum is responsible for the food breaking down process, while the jejenum and ileum help in further digestion. The small intestine epithelium consists in four layers: mucosa, submucosa, muscle layer, and adventitia. Mucosa has multiple projections that increase surface volume ratio. This projections increase contact with food, which helps to ingest more nutrientes while digestion and food transport is occurring.