Digestion is the mechanical and chemical breakdown of foods into smaller components that can be absorbed. Mechanical digestion breaks down food into smaller particles. Chemical digestion consists of hydrolysis reactions that break down dietary macromolecules into their monomers, which allows for the absorption of nutrients. The organs of the digestive system carry out these processes. The digestive system consists of the digestive tract (alimentary canal), which extends from the mouth to the anus, and several accessory organs, which release secretions into the canal. The alimentary canal includes the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anal canal; the accessory organs include the teeth, tongue, salivary glands, liver, gallbladder, and pancreas.