Final answer:
Digestion is the mechanical and chemical breakdown of food in the gastrointestinal tract. The GI tract includes several organs where different stages of digestion and nutrient absorption occur, starting with the mouth and ending with the large intestine.
Step-by-step explanation:
1. Digestion is the mechanical and chemical processes taking place in the gastrointestinal tract by which food is broken down into absorbable forms. It is related to, but not the same as metabolism.
2. The gastrointestinal (GI) tract or digestive canal is the system of organs that takes food, digests it to extract energy and nutrients, and expels the remaining waste.
3. The mouth or buccal cavity or oral cavity is the orifice through which we take in food or water.
Digestion includes both mechanical digestion, which begins in the mouth with the process of chewing, and chemical digestion, where enzymes break down food into small molecules. Absorption of these nutrients occurs in the bloodstream, primarily in the small intestine. The large intestine is responsible for water absorption and the formation of feces.