The section of the large intestine extending from the cecum to the rectum.
[Middle English, from Latin, from Greek kolon, large intestine.]
colonic co·lon'ic (kə-lŏn'ĭk) adj.
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The section of the large intestine extending from the cecum to the rectum.
[Middle English, from Latin, from Greek kolon, large intestine.]
colonic co·lon'ic (kə-lŏn'ĭk) adj.The portion of the intestine that runs from the cecum to the rectum; in some mammals, it may be separated from the small intestine by an ileocecal valve. It is also known as the large intestine. The colon is usually divided into ascending, transverse, and descending portions. In the human a fourth section, the sigmoid, is found. The colon is longer in herbivores and shorter in carnivores, and is about 4 to 6 ft (1.2 to 1.8 m) long in humans. No digestive enzymes are secreted in the colon. Much digestion (for example, all breakdown of cellulose) occurs by bacteria, of which Escherichia coli is the most common. Most of the fluid added to the food during digestion is reabsorbed into the body in the colon. All digestive action, water absorption, and so on, is completed before the food materials pass out of the colon into the rectum. See also Digestive system.
Also known as the large intestine, or sometimes the large bowel, because it is wider, although much shorter, than the small intestine, which leads into it via the caecum. There are three components: ascending, from the lower right side of the abdominal cavity; transverse, crossing to the left; and descending, to the lower left where it leads into the rectum. Its main function is the absorption of water, changing the liquid contents received from the ileum into the normally semi-solid faeces.
— Stuart Judge
See alimentary system.
Also known as the large intestine or bowel, consisting of three anatomical regions: the ascending, the transverse, and the descending colon. The colon normally has a considerable population of bacteria, while it is rare to find a significant bacterial population in the small intestine. The colon terminates at the rectum, where faeces are compacted and stored before voiding. See also gastro-intestinal tract.
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The main part of the large intestine. Its main function is to absorb large amounts of water and electrolytes from undigested food passing through the colon from the small intestine to the rectum.
The middle and longest part of the large intestine. (See digestive system.)
Pertaining to or arising from the colon.
| It has been suggested that this article or section be merged with Large intestine. (Discuss) |
| Colon (anatomy) | |
|---|---|
| Front of abdomen, showing surface markings for liver, stomach, and large intestine. | |
| Gray's | subject #249 1177 |
| Dorlands/Elsevier | c_47/12249855 |
In the anatomy of the digestive system, the colon is another name for the large intestine. The main function of the colon appears to be extraction of water from feces. In mammals, it consists of the ascending colon, transverse colon, the descending colon, and the sigmoid colon. The colon from cecum to the mid-transverse colon is also known as the right colon. The remainder is known as the left colon.
The location of the parts of the colon are either in the abdominal cavity or behind it in the retroperitoneum. The colon in those areas is fixed in location.
Arterial supply to the colon comes from branches of the superior and inferior mesenteric arteries. Flow between these two systems communicates via a "marginal artery" that runs parallel to the colon for its entire length. The arc of Riolan, or the meanering mesenteric artery, is a variable vessel conecting the proximal SMA to the proximal IMA that can be extremely important if either vessel is occluded.
Venous drainage usually mirrors colonic arterial supply, with the inferior mesenteric vein draining into the splenic vein, and the superior mesenteric vein joining the splenic vein to form the portal vein that then enters the liver.
Lymphatic drainage from the entire colon and proximal two-thirds of the rectum is to the paraortic nodes that then drain into the cisterna chyli. The lymph from the remaining rectum and anus can either follow the same route, or drain to the internal illiac and superficial inguinal nodes. The dentate line only roughly marks this transition.
The ascending colon, on the right side of the abdomen, is about 12.5 cm long. It is the part of the colon from the cecum to the hepatic flexure (the turn of the colon by the liver). It is retroperitoneal in most humans. In grazing animals the cecum empties into the spiral colon. Anteriorly it is related to the coils of small intestine, the right edge of the greater omentum, and the anterior abdominal wall. Posteriorly, it is related to the iliacus, the iliolumbar ligament, the quadratus lumborum, the transverse abdominis, the diaphragm at the tip of the last rib; the lateral cutaneous, ilioinguinal, and iliohypogastric nerves; the iliac branches of the iliolumbar vessels, the fourth lumbar artery, and the right kidney.
The ascending colon is supplied by parasympathetic fibers of the vagus nerve (CN X).
Arterial supply of the ascending colon comes from the ileocolic artery and right colic artery, both branches of the SMA. While the ileocolic artery is almost always present, the right colic can be absent in 5-15% of individuals.
The transverse colon is the part of the colon from the hepatic flexure (the turn of
the colon by the liver) to the splenic flexure (the turn
of the colon by the spleen). The transverse colon hangs off the stomach, attached to it by a wide band of
The transverse colon is encased in peritoneum, and is therefore mobile (unlike the parts of the colon immediately before and after it). More cancers form as the large intestine goes along and the contents become more solid (water is removed) in order to form feces.
The proximal two-thirds of the transverse colon is perfused by the middle colic artery, a branch of superior mesenteric artery, while the latter third is supplied by branches of the inferior mesenteric artery. The "watershed" area between these two blood supplies, which represents the embryologic division between the midgut and hindgut, is an area sensitive to ischemia.
The descending colon is the part of the colon from the splenic flexure to the beginning of the sigmoid colon. It is retroperitoneal in two-thirds of humans. In the other third, it has a (usually short) mesentery. Arterial supply comes via the left colic artery.
The sigmoid colon is the part of the large intestine after the descending colon and before the rectum. The name sigmoid means S-shaped (see sigmoid). The walls of the sigmoid colon are muscular, and contract to increase the pressure inside the colon, causing the stool to move into the rectum.
The sigmoid colon is supplied with blood from several branches (usually between 2 and 6) of the sigmoid arteries, a branch of the IMA. The IMA terminates as the superior rectal artery.
Sigmoidoscopy is a common diagnostic technique used to examine the sigmoid colon.
One variation on the normal anatomy of the colon occurs when extra loops form, resulting in a longer than normal organ. This condition, referred to as redundant colon, typically has no direct major health consequences, though rarely volvulus occurs resulting in obstruction and requiring immediate medical attention.[1] A significant indirect health consequence is that use of a standard adult colonoscope is difficult and in some cases impossible when a redundant colon is present, though specialized variants on the instrument (including the pediatric variant) are useful in overcoming this problem.[2]
The large intestine comes after the small intestine in the digestive tract and measures approximately 1.5 meters in length. Although there are differences in the large intestine between different organisms, the large intestine is mainly responsible for storing waste, reclaiming water, maintaining the water balance, and absorbing some vitamins, such as vitamin K.
By the time the chyme has reached this tube, almost all nutrients and 90% of the water have been absorbed by the body. At this point some electrolytes like sodium, magnesium, and
chloride are left as well as indigestible carbohydrates
known as dietary fiber. As the chyme moves through the large intestine, most of the remaining water
is removed, while the chyme is mixed with mucus and bacteria
known as gut flora, and becomes feces. The bacteria break down some of the fiber for their own nourishment and create acetate, propionate, and butyrate as waste products, which in turn are used by the
cell lining of the colon for nourishment. This is an example of a symbiotic relationship and
provides about one hundred Calories a day to the body. The large intestine produces no digestive
enzymes — chemical digestion is completed in the
small intestine before the chyme reaches the large intestine. The pH in the colon varies between 5.5 and 7 (slightly
There are a number of diseases or disorders of the colon:
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Dansk (Danish)
1.
n. - tyktarm, colon
2.
n. - kolon
3.
n. - nybygger
Nederlands (Dutch)
karteldarm, dubbele punt
Français (French)
1.
n. - (Anat) côlon
2.
n. - (Ling) deux points
3.
n. - colon (d'une ferme ou d'une plantation)
Deutsch (German)
1.
n. - Doppelpunkt
2.
n. - Grimmdarm
3.
n. - Colon (Währungseinheit in Costa Rica u. El Salvador)
Ελληνική (Greek)
n. - (ανατ.) κόλον, (τυπογρ.) άνω και κάτω τελεία (:)
Italiano (Italian)
colon, due punti
Português (Portuguese)
n. - dois (m pl) pontos (Gram.), cólon (m) (Anat.)
Русский (Russian)
ободочная кишка, двоеточие
Español (Spanish)
1.
n. - colon
2.
n. - dos puntos
3.
n. - parte principal de un período
Svenska (Swedish)
n. - grovtarm, kolon
中文(简体) (Chinese (Simplified))
1. 结肠
2. 冒号
3. 科朗
中文(繁體) (Chinese (Traditional))
1.
n. - 冒號
2.
n. - 結腸
3.
n. - 科朗
한국어 (Korean)
1.
n. - 구두점의 하나인 콜론
2.
n. - 결장, 대장 전체
3.
n. - 코스타리카 화폐단위 콜론
العربيه (Arabic)
(الاسم) قولون, الأمعاء الغليظه, نقطتان):( في الكتابه أو الطباعه
עברית (Hebrew)
n. - המעי הגס
n. - נקודתיים
n. - מטבע הנהוגה באמריקה המרכזית, בעל משק או מטעים בייחוד באלג'יריה
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