The terminal portion of the small intestine extending from the jejunum to the cecum.
[Late Latin īleum, groin, flank, variant of Latin īlia.]
ileal il'e·al adj.
Dictionary:
il·e·um (ĭl'ē-əm) ![]() |
[Late Latin īleum, groin, flank, variant of Latin īlia.]
ileal il'e·al adj.| 5min Related Video: ileum |
| Britannica Concise Encyclopedia: ileum |
For more information on ileum, visit Britannica.com.
| World of the Body: ileum |
The section of the small intestine beyond the duodenum and the jejunum, and ending where it joins the caecum. Digestion is mostly completed before this point, but absorption into the blood of the resulting simpler substances continues here. The surface area of the lining is increased (though less than in the jejunum) by its folds and protrusions (villi). The last part of the ileum has a unique and essential function in the absorption of vitamin B12, necessary for normal blood formation.
— Stuart Judge
See alimentary system.
| Food and Nutrition: ileum |
Last portion of the small intestine, between the jejunum and the colon (large intestine); see gastro-intestinal tract.
| Sports Science and Medicine: ileum |
Part of the alimentary canal between the duodenum and colon, in which food is absorbed and digestion completed.
| Veterinary Dictionary: ileum |
The distal portion of the small intestine, extending from the jejunum to the cecum. See also ileal.
| Wikipedia: Ileum |
| This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations. Please improve this article by introducing more precise citations where appropriate. (April 2009) |
| Ileum | |
|---|---|
| Small intestine | |
| The cecal fossa. The ileum and cecum are drawn backward and upward. | |
| Gray's | subject #248 1171 |
| Artery | ileal arteries |
| Vein | ileal veins |
| Nerve | celiac ganglia, vagus [1] |
| Precursor | midgut |
| Dorlands/Elsevier | Ileum |
The ileum 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]
The ileum follows the duodenum and jejunum, and is separated from the cecum by the ileocecal valve (ICV). In humans, the ileum is about 2-4 m long, and the pH is usually between 7 and 8 (neutral or slightly alkaline).
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The function of the ileum is mainly to absorb vitamin B12 and bile salts and whatever products of digestion were not absorbed by the jejunum. The wall itself is made up of folds, each of which has many tiny finger-like projections known as villi on its surface. In turn, the epithelial cells which line these villi possess even larger numbers of microvilli. Therefore the ileum has an extremely large surface area both for the adsorption (attachment) of enzyme molecules and for the absorption of products of digestion. The DNES (diffuse neuroendocrine system) cells of the ileum secrete various hormones (gastrin, secretin, cholecystokinin) into the blood. Cells in the lining of the ileum secrete the protease and carbohydrase enzymes responsible for the final stages of protein and carbohydrate digestion into the lumen of the intestine. These enzymes are present in the cytoplasm of the epithelial cells.
The villi contain large numbers of capillaries which take the amino acids and glucose produced by digestion to the hepatic portal vein and the liver. Lacteals are small lymph vessels, and are present in villi. They absorb fatty acid and glycerol, the products of fat digestion. Layers of circular and longitudinal smooth muscle enable the digested food to be pushed along the ileum by waves of muscle contractions called peristalsis.
There is no line of demarcation between the jejunum and the ileum. There are, however, subtle differences between the two.
In the fetus the ileum is connected to the navel by the vitelline duct. In roughly 3% of humans, this duct fails to close during the first seven weeks after birth, causing a condition called Meckel's diverticulum.
In veterinary anatomy, the ileum is distinguished from the jejunum by being that portion of the jejunoileum that is connected to the caecum by the ileocecal fold.
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Goblet cell in ileum |
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| Translations: Ileum |
Nederlands (Dutch)
kronkeldarm
Français (French)
n. - (Anat) iléon
Deutsch (German)
n. - Ileum, Krummdarm
Ελληνική (Greek)
n. - (ανατ.) ειλεός
Português (Portuguese)
n. - íleo (m) (Anat.) (Patol.)
Русский (Russian)
подвздошная кишка
Svenska (Swedish)
n. - ileum (nedersta delen av tunntarm)
中文(简体)(Chinese (Simplified))
回肠
中文(繁體)(Chinese (Traditional))
n. - 迴腸
العربيه (Arabic)
(الاسم) اللفائفي
עברית (Hebrew)
n. - המעי העקום
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![]() | Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved. Read more | |
![]() | Britannica Concise Encyclopedia. Britannica Concise Encyclopedia. © 2006 Encyclopædia Britannica, Inc. All rights reserved. Read more | |
![]() | World of the Body. The Oxford Companion to the Body. Copyright © 2001, 2003 by Oxford University Press. All rights reserved. Read more | |
![]() | Food and Nutrition. A Dictionary of Food and Nutrition. Copyright © 1995, 2003, 2005 by A. E. Bender and D. A. Bender. All rights reserved. Read more | |
![]() | Sports Science and Medicine. The Oxford Dictionary of Sports Science & Medicine. Copyright © Michael Kent 1998, 2006, 2007. All rights reserved. Read more | |
![]() | Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved. Read more | |
![]() | Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Ileum". Read more | |
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