Host gastrointestinal system (GI system)

The **host gastrointestinal system**—commonly referred to as the **GI system** or digestive system—is a continuous tract extending from the mouth to the anus, comprising major organs such as the oral cavity, pharynx, esophagus, stomach, small intestine (duodenum, jejunum, ileum), large intestine (colon, rectum, anus), and accessory organs (pancreas, liver, gallbladder)[4][5][8]. Its primary roles are to ingest and digest food, absorb nutrients, and expel waste[1][3][5]. It employs coordinated peristaltic muscle contractions and complex secretions from glands and accessory organs to achieve these functions[5][8]. The system contains a large number of immune cells and harbors the gut microbiota, which profoundly impact metabolism and immunity[2][4][8]. Disorders affecting the gastrointestinal system include cancers, inflammatory conditions, states of malabsorption, infectious diseases, and functional syndromes[4][5]. Drugs and interventions generally target specific receptors, transporters, enzymes, or cellular functions within this system, not the system as a whole.

Other names

Gastrointestinal systemDigestive systemGI tractAlimentary canal