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.
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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.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.
Last portion of the small intestine, between the jejunum and the colon (large intestine); see gastro-intestinal tract.
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Part of the alimentary canal between the duodenum and colon, in which food is absorbed and digestion completed.
The distal portion of the small intestine, extending from the jejunum to the cecum. See also ileal.
| Ileum | |
|---|---|
| Small intestine | |
| The cecal fossa. The ileum and cecum are drawn backward and upward. | |
| Gray's | subject #248 1171 |
| Artery | intestinal arteries |
| Nerve | celiac ganglia, vagus [1] |
| Precursor | midgut |
In anatomy of the digestive system, the ileum is the final section of the small intestine. It is about 2-4 m long in humans, follows the duodenum and jejunum, and is separated from the cecum by the ileocecal valve (ICV). The pH in the ileum is usually between 7 and 8 (neutral or slightly alkaline).
Its function is mainly to absorb vitamin B12 and bile salts and whatever products of digestion that 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 that line the ileum contain the protease and carbohydrase enzymes (gastrin, secretin, cholecystokinin) responsible for the final stages of protein and carbohydrate digestion. 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.
These unencapsulated lymphoid nodules contain large amounts of lymphocytes and other cells of the immune system.
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 ileocaecal fold.
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Goblet cell in ileum |
| Anatomy of torso, digestive system: Gastrointestinal tract | |
|---|---|
| Upper GI: to stomach | Mouth • Pharynx (nasopharynx, oropharynx, hypopharynx) • Esophagus • Crop |
| Upper GI: stomach | rugae - gastric pits - cardia/gland - fundus/gland - pylorus/gland - pyloric antrum - greater curvature - lesser curvature |
| Lower GI: intestines | Small intestine (duodenum, jejunum, ileum) • Vermiform appendix • Ileocecal valve - Large intestine: Cecum • Colon (ascending colon, hepatic flexure, transverse colon, splenic flexure, descending colon, sigmoid colon) |
| Lower GI: after intestines | Rectum (Houston valve, rectal ampulla, pectinate line) • Anal canal (anal valves, anal sinuses, anal columns) - Anus: Sphincter ani internus muscle • Sphincter ani externus muscle |
| Lower GI: continuous | GALT: Peyer's patches • M cells - intestinal villus • crypts of Lieberkühn • circular folds • taenia coli • haustra • epiploic appendix |
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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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