#digestive system
- Anus — The external terminal opening of the human and animal digestive tract, located at the lower extremity of the rectum, through which solid waste products of digestion (feces) are evacuated from the body; it is a complex muscular structure controlled by internal and external sphincters.
- Digestive system — A complex assembly of structurally and functionally correlated organs (oral cavity, pharynx, esophagus, stomach, intestines, liver, and pancreas) responsible for the ingestion, fragmentation, digestion of food, absorption of essential nutrients, and elimination of unassimilable residues. This macroscopic system guarantees the energy supply of the entire organism through the chemical and mechanical transformation of nutrients.