Means of - or pertaining to - the stomach. Gastrointestinal means "of or pertaining to the stomach and intestines”. The Gastrointestinal (GI) tract is a region that includes the mouth, esophagus, stomach, intestines, rectum and anus. This is also called the alimentary tract. Gastroenterology is the science and study of the GI tract. A gastroenterologist is a doctor that studies and treats diseases and symptoms of the GI tract. Additional Info: You will sometimes See: References to the "upper GI tract" or "lower GI symptoms". The upper gastrointestinal tract refers to the region from the mouth to the stomach. The lower gastroinestinal tract includes everything from the large intestine to the rectum. The GI tract is part of the digestive tract, which is responsible for the digestion of food. The digestive tract includes additional components such as the liver, salivary glands, pancreas etc. Your gastric juices (stomach acid) are very acidic, with a pH of 1 to 2! MSDS Relevance: On an MSDS, the term gastric might be found in reference to symptoms of ingestion of a toxic material (example, "symptoms include gastric distress, nausea and vomiting"). The term might also appear in reference to a treatment for ingested poison called gastric lavage which involves washing the stomach with large quantities of saline, followed by suctioning. This process is more commonly known as "pumping one's stomach". The term "gastrointestinal" may appear on an MSDS in reference to upper or lower GI symptoms. Upper GI symptoms might include nausea, stomach ache and reflux, while lower GI symptoms include diarrhea, constipation and rectal bleeding. See also: Catharsis, Emesis, Gastroenteritis, Nausea, Poison