The human gastrointestinal tract is the stomach and intestine, sometimes including all the structures from the mouth to the anus. (The "digestive system" is a broader term that includes other structures, including the accessory organs of digestion).
In an adult male human, the gastrointestinal (GI) tract is 5 metres (20 ft) long in a live subject, or up to 9 metres (30 ft) without the effect of muscle tone, and consists of the upper and lower GI tracts. The tract may also be divided into foregut, midgut, and hindgut, reflecting the embryological origin of each segment of the tract.
The GI tract always releases hormones to help regulate the digestion process. These hormones, including gastrin, secretin, cholecystokinin, and grehlin, are mediated through either intracrine or autocrine mechanisms, indicating that the cells releasing these hormones are conserved structures throughout evolution.
Read more about Human Gastrointestinal Tract: Upper Gastrointestinal Tract, Lower Gastrointestinal Tract, Embryology, Transit Time, Pathology, Immune Function, Histology
Famous quotes containing the words human and/or tract:
“She had no longer any relish for her once favorite amusement of reading. And mostly she disliked those authors who have penetrated deeply into the intricate paths of vanity in the human mind, for in them her own folly was continually brought to her remembrance and presented to her view.”
—Sarah Fielding (1710–1768)
“If a theme or idea is too near the surface, the novel becomes simply a tract illustrating an idea.”
—Elizabeth Bowen (1899–1973)