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The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller components, until they can be absorbed and assimilated into the body.
The ileum (/ ˈ ɪ l i əm /) is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish , the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum. [ 2 ]
Its length is about 1.5 m, and the area of the mucosa in an adult human is about 2 m 2 (22 sq ft). [19] The longest part of the large intestine is the colon whose main function is to absorb water and salts. [21] The large intestine begins at the cecum, where the appendix is located.
The ileum joins to the cecum of the large intestine at the ileocecal junction. [citation needed] The jejunum and ileum are suspended in the abdominal cavity by mesentery. The mesentery is part of the peritoneum. Arteries, veins, lymph vessels and nerves travel within the mesentery. [13]
The histology of the ileocecal valve shows an abrupt change from a villous mucosa pattern of the ileum to a more colonic mucosa. A thickening of the muscularis mucosa, [citation needed] which is the smooth muscle tissue found beneath the mucosal layer of the digestive tract.
The descending colon is the part of the colon from the splenic flexure to the beginning of the sigmoid colon. One function of the descending colon in the digestive system is to store feces that will be emptied into the rectum. It is retroperitoneal in two-thirds of humans. In the other third, it has a (usually short) mesentery. [20]
The cecum is an end point for the colon with a dead-end portion terminating with the appendix. [8] The connection between the end of the small intestine (ileum) and the start (as viewed from the perspective of food being processed) of the colon (cecum) is now clearly understood, and is called the ileocecal orifice.
Crohn's most commonly affects the end of the small bowel (the ileum) and the beginning of the colon, but it may affect any part of the GI tract. Crohn's disease affects both the large and small intestine. Infection of the appendix is appendicitis. When there is a buildup of bacteria, the appendix can get inflamed and swollen, and this leads to ...