In anatomy, the intestine is the segment of the alimentary canal extending from the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine. In humans, the small intestine is further subdivided into the duodenum, jejunum and ileum while the large intestine is subdivided into the cecum and colon. Image File history File links Stomach_colon_rectum_diagram. ... Human heart and lungs, from an older edition of Grays Anatomy. ... Gut redirects here. ... In anatomy, the stomach is a bean-shaped hollow muscular organ of the gastrointestinal tract involved in the second phase of digestion, following mastication. ... This article is about the bodily orifice. ... In biology the small intestine is the part of the gastrointestinal tract (gut) between the stomach and the large intestine and includes the duodenum, jejunum, and ileum. ... The large intestine, an organ which is now more commonly referred to by its Greek name, the colon, is the last part of the digestive system: the final stage of the alimentary canal in vertebrate animals. ... In anatomy of the digestive system, the duodenum is a hollow jointed tube about 25-30 cm long connecting the stomach to the jejunum. ... Diagram of the Human Intestine In anatomy of the digestive system, the jejunum is the central of the three divisions of the small intestine and lies between the duodenum and the ileum. ... Grays Fig. ... The large intestine, an organ which is now more commonly referred to by its Greek name, the colon, is the last part of the digestive system: the final stage of the alimentary canal in vertebrate animals. ...

Structure and Function

The intestinal tract can be broadly divided into two different parts, the small and large intestine. Grayish-purple in color and about 35 mm (1.5 inches) in diameter, the small intestine is the first and longest, measuring 6 meters (20 feet) long average in an adult man. Shorter and relatively stockier, the large intestine is a dark reddish color, measuring roughly 1.5 meters (5 feet) long on average. Both intestines share a general structure with the whole gut, and are composed of several layers. The lumen is the cavity where digested material passes through and from where nutrients are absorbed. Along the whole length of the gut in the glandular epithelium are goblet cells. These secrete mucus which lubricates the passage of food along and protects it from digestive enzymes. Villi are vaginations of the mucosa and increase the overall surface area of the intestine while also containing a lacteal, which is connected to the lymph system and aids in the removal of lipids and tissue fluid from the blood supply. Micro villi are present on the epithelium of a villus and further increase the surface area over which absorption can take place. artery anatomy, showing lumen The lumen (pl. ... Goblet cells are glandular simple columnar epithelial cells whose sole function is to secrete mucus. ... Mucus is a slippery secretion of the lining of the mucous membranes in the body. ... Intestinal villi (singular: villus) are tiny, finger-like structures that protrude from the wall of the intestine and have additional extensions called microvilli (singular: microvillus) which protrude from epithelial cells lining villi. ... The mucous membranes (or mucosae; singular: mucosa) are linings of mostly endodermal origin, covered in epithelium, and are involved in absorption and secretion. ... A lacteal is a lymphatic capillary that absorbs dietary fats in the villi of the small intestine. ... The human lymphatic system The lymphatic system is a complex network of lymphoid organs, lymph nodes, lymph ducts, lymphatic tissues, lymph capillaries and lymph vessels that produce and transport lymph fluid from tissues to the circulatory system. ... Some common lipids. ...

The next layer is the muscularis mucosa which is a layer of smooth muscle that aids in the action of continued peristalsis along the gut. The submucosa contains nerves, blood vessels and elastic fibre with collagen that stretches with increased capacity but maintains the shape of the intestine. Surrounding this is the muscularis externa which comprises longitudinal and smooth muscle that again helps with continued peristalsis and the movement of digested material out of and along the gut. Gut redirects here. ... Gut redirects here. ...

Lastly there is the serosa which is made up of loose connective tissue and coated in mucus so as to prevent friction damage from the intestine rubbing against other tissue. Holding all this in place are the mesenteries which suspend the intestine in the abdominal cavity and stop it being disturbed when a person is physically active. A serous membrane is a very thin layer of cells (usually one row) covering internal body cavity. ... In anatomy, a mesentery is a part of the peritoneum that connects an internal organ, such as the small intestine, to the abdominal wall. ...

The large intestine hosts several kinds of bacteria that deal with molecules the human body is not able to breakdown itself. This is an example of symbiosis. These bacteria also account for the production of gases inside our intestine (this gas is released as flatulence when removed through the anus). However the large intestine is mainly concerned with the absorption of water from digested material (which is regulated by the hypothalamus), the reabsorption of sodium, as well as any nutrients that may have escaped primary digestion in the ileum. Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... For other uses, see Symbiosis (disambiguation). ... Flatulence is the presence of a mixture of gases known as flatus in the digestive tract of mammals expelled from the rectum. ... The hypothalamus links the nervous system to the endocrine system via the pituitary gland (hypophysis). ... For sodium in the diet, see Edible salt. ...

Diseases

• Gastroenteritis is inflammation of the intestines and is the most common disease of the intestines. It can arise as the result of food poisoning.
• Ileus is a blockage of the intestines.
• Ileitis is an inflammation of the ileum.
• Colitis is an inflammation of the large intestine.
• Appendicitis is inflammation of the vermiform appendix located at the cecum. This is a potentially fatal disease if left untreated; most cases of appendicitis require surgical intervention.
• Coeliac disease is a common form of malabsorption, affecting up to 1% of people of northern European descent. Allergy to gluten proteins, found in wheat, barley and rye, causes villous atrophy in the small intestine. Life-long dietary avoidance of these foodstuffs in a gluten-free diet is the only treatment.
• Crohn's disease and ulcerative colitis are examples of inflammatory bowel disease. While Crohn's can affect the entire gastrointestinal tract, ulcerative colitis is limited to the large intestine. Crohn's disease is widely regarded as an autoimmune disease. Although ulcerative colitis is often treated as though it were an autoimmune disease, there is no consensus that it actually is such. (See List of autoimmune diseases).
• Enteroviruses are named by their transmission-route through the intestine (enteric = related to intestine), but their symptoms aren't mainly associated with the intestine.

See also Bacterial gastroenteritis and Diarrhea Gastroenteritis is a general term referring to inflammation or infection of the gastrointestinal tract, primarily the stomach and intestines. ... A foodborne illness (also foodborne disease) is any illness resulting from the consumption of food. ... Ileus, formerly called iliac passion, refers to limited or absent intestinal passage. ... Crohns disease is a chronic inflammatory disease of the alimentary tract and it can involve any part of it - from the mouth to the anus. ... Grays Fig. ... Colitis is a digestive disease characterized by inflammation of the colon. ... The large intestine, an organ which is now more commonly referred to by its Greek name, the colon, is the last part of the digestive system: the final stage of the alimentary canal in vertebrate animals. ... Appendicitis (or epityphlitis) is a condition characterized by inflammation of the appendix[1]. While mild cases may resolve without treatment, most require removal of the inflamed appendix, either by laparotomy or laparoscopy. ... In human anatomy, the vermiform appendix (or appendix, pl. ... Coeliac disease or celiac disease is an autoimmune disorder of the small bowel that occurs in genetically predisposed individuals in all age groups after early infancy. ... Crohns disease (also known as regional enteritis) is a chronic, episodic, inflammatory condition of the gastrointestinal tract characterized by transmural inflammation (affecting the entire wall of the involved bowel) and skip lesions (areas of inflammation with areas of normal lining between). ... In medicine, inflammatory bowel disease (IBD) is a group of inflammatory conditions of the large intestine and, in some cases, the small intestine. ... Autoimmunity is the failure of an organism to recognize its own constituent parts (down to the sub-molecular levels) as self, which results in an immune response against its own cells and tissues. ... Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. ... Species Bovine enterovirus Human enterovirus A Human enterovirus B Human enterovirus C Human enterovirus D Human enterovirus E Poliovirus Porcine enterovirus A Porcine enterovirus B The enteroviruses are a genus of (+)ssRNA viruses associated with several human and mammalian diseases. ...

Disorders

• Irritable bowel syndrome is the most common functional disorder of the intestine. Functional constipation and chronic functional abdominal pain are other disorders of the intestine that have physiological causes, but do not have identifiable structural, chemical, or infectious pathologies. They are aberrations of normal bowel function but not diseases.

[Diverticular disease] is a condition that is very common in older people in industrialized countries. It usually affects the large intestine but has been known to affect the small intestine as well. Diverticular disease occurs when pouches form on the intestinal wall. Once the pouches become inflamed it is known as Diverticulitis, (or Diverticular disease.) Chronic functional abdominal pain (CFAP) is the ongoing presence of abdominal pain for which there is no physical explanation. ... Diverticulitis is a common digestive disorder particularly found in the large intestine. ...

• Endometriosis can affect the intestines, with similar symptoms tgulation) is a comparatively rare event (usually developing sometime after major bowel surgery). It is, however, hard to diagnose correctly, and if left uncorrected can lead to bowel infarction and death. (The singer Maurice Gibb is understood to have died from this.)

This article does not adequately cite its references or sources. ... Maurice Ernest Gibb CBE (December 22, 1949 – January 12, 2003), was a musician and singer-songwriter. ...

References

This article or section is missing citations or needs footnotes. Using inline citations helps guard against copyright violations and factual inaccuracies.

• Encyclopædia Britannica article on intestine retrieved on 2007-03-27
• KMLE Medical Dictionary definition of intestine retrieved from KMLE Medical Dictionary on 2007-03-27

Image File history File links Emblem-important. ...

See also

Look up Intestine in
Wiktionary, the free dictionary.

• Inflammatory bowel disease (or "IBD")
• Diarrhea
• Constipation