ileum

ileal, adj.
/il"ee euhm/, n., pl. ilea /il"ee euh/.
1. Anat. the third and lowest division of the small intestine, extending from the jejunum to the cecum. See diag. under intestine.
2. Zool. the anterior portion of the hindgut of an insect or other arthropod.
[1675-85; < NL, ML ileum, var. of L ilia (neut. pl.) side of the body between hips and groin, guts, appar. by confusion with L ileus ILEUS]

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Final and longest segment of the small intestine.

It is the site of absorption of vitamin B12 (see vitamin B complex) and reabsorption of about 90% of conjugated bile salts. It extends about 13 ft (4 m), from the jejunum (middle section of the small intestine) to the ileocecal valve, where it joins the large intestine. Disorders produce vitamin B12 deficiency and extensive diarrhea (since bile salts in the large intestine interfere with water absorption).

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 the final and longest segment of the small intestine. It is specifically responsible for the absorption of vitamin B12 and the reabsorption of conjugated bile salts. The ileum is about 4 metres (13 feet) long and extends from the jejunum (the middle section of the small intestine) to the ileocecal valve, which empties into the colon ( large intestine). The ileum is suspended from the abdominal wall by the mesentery, a fold of serous (moisture-secreting) membrane.

      The smooth muscle of the ileum's walls is thinner than the walls of other parts of the intestines, and its peristaltic contractions are slower. The ileum's lining is also less permeable than that of the upper small intestine. Small collections of lymphatic tissue (Peyer patches (Peyer patch)) are embedded in the ileal wall, and specific receptors for bile salts and vitamin B (vitamin B12)12 are contained exclusively in its lining; about 90 percent of the conjugated bile salts in the intestinal contents is absorbed by the ileum.

      Two percent of all humans are born with a congenital ileum malformation, called Meckel diverticulum, that consists of a side channel up to 5 cm (2 inches) long extending from the intestinal wall. The malformation occurs when the duct leading from the navel to the small intestine in the fetus fails to atrophy and close. A small number of cases require surgical removal because of intestinal bleeding and inflammation.

      Injury or disease affecting the terminal ileum produces vitamin B12 deficiency and extensive diarrhea, the latter resulting from the interference of bile salts on water absorption in the large intestine.

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Universalium. 2010.

Look at other dictionaries:

  • Ileum — Il e*um, n. [L. ile, ileum, ilium, pl. ilia, groin, flank.] 1. (Anat.) The last, and usually the longest, division of the small intestine; the part between the jejunum and large intestine. [Written also {ileon}, and {ilium}.] [1913 Webster] 2.… …   The Collaborative International Dictionary of English

  • ileum — (n.) lowest part of the small intestine, 1680s, medical Latin, from ileum, singular created from classical Latin plural ilia groin, flank, in classical Latin, belly, the abdomen below the ribs, poetically, entrails, guts. Sense restriction and… …   Etymology dictionary

  • ileum — ilèum (ȉleum) m DEFINICIJA anat. zadnji dio tankog crijeva, »vito crijevo« ETIMOLOGIJA srlat. ← grč. eílein: savijati …   Hrvatski jezični portal

  • Ilĕum — Ilĕum, gewundener Darm, s. Darmkanal. I. os (Ilei os), Darmbein, s.u. Beckenknochen. Ileus, Darmgicht …   Pierer's Universal-Lexikon

  • Ilĕum — (lat.), der Krummdarm, s. Darm, S. 520 …   Meyers Großes Konversations-Lexikon

  • Ileum — Ilĕum (grch.), die untere Hälfte des Dünndarms …   Kleines Konversations-Lexikon

  • Ileum — Ileum, lat., die 2. Hälfte der dünnen Gedärme; s. Darm; Ileitis, Entzündung des I.; Ileus, Schnürung des I., Krankheit (Volvulus, Miserere, Kothbrechen); Iliacum, was zum I. gehört; os iliacum Hüftbein; ilio costalis, Muskel vom Hüftbein zu den… …   Herders Conversations-Lexikon

  • ileum — ILÉUM s.n. v. ileon. Trimis de LauraGellner, 13.09.2007. Sursa: DN …   Dicționar Român

  • ileum — ► NOUN (pl. ilea) Anatomy ▪ the third portion of the small intestine, between the jejunum and the caecum. ORIGIN Latin, variant of ILIUM(Cf. ↑ilium) …   English terms dictionary

  • ileum — [il′ē əm] n. pl. ilea [il′ēə] [ModL < L, flank, groin (var. of ilium, ile): form prob. infl. by ileus (see ILEUS) < ?] the lowest part of the small intestine, opening into the large intestine: see INTESTINE …   English World dictionary

  • Ileum — Infobox Anatomy Name = Ileum Latin = Orckecme GraySubject = 248 GrayPage = 1171 Caption = Small intestine Caption2 = The cecal fossa. The ileum and cecum are drawn backward and upward. Precursor = midgut System = Artery = ileal arteries Vein =… …   Wikipedia

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