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intestine, muscular hoselike portion of the gastrointestinal tract extending from the lower end of the stomach (pylorus) to the anal opening. In humans this fairly narrow (about 1 in./2.5 cm) tubelike structure winds compactly back and forth within the abdominal cavity for about 23 ft (7 m), and is known as the small intestine. It is not only an organ of digestion (for that part of the process not completed by the stomach) but is the chief organ of absorption. By contraction of its muscular walls (peristalsis) the food mass is propelled onward and, as it is carried along, it is subject to the digestive action of the secretions of the intestinal lining as well as to that of bile and pancreatic juice which enter the upper intestine (duodenum) from ducts leading from the liver and pancreas. Innumerable minute projections (villi) in the intestinal mucous lining absorb the altered food for distribution by the blood and lymphatic systems to the rest of the body. Food continues to pass into the middle (jejunum) and end (ileum) of the small intestines.

The small intestine joins the large intestine, or colon, at the cecum in the right lower abdominal cavity. Here, also, is the appendix, a blind pouch projecting from the cecum. The large intestine is wider in diameter. Its direction as it leaves the cecum is upward (ascending colon), across the abdominal cavity (transverse colon) beneath the stomach, and then downward (descending colon) on the left side of the abdominal cavity, making a sharp turn in the left lower portion (sigmoid) to merge with the rectum. In all, the large intestine is about 5 ft (1.5 m) long. Bacteria, the indigestible residue of food, and mucus form the bulk of matter in the large intestine. The water content of the bulk is absorbed through the walls of the large intestine, and the solid matter is excreted through the rectum.

See digestive system.

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The last portion of the small intestine, extending from the jejunum to the large intestine.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


1. the part of the small intestine between the jejunum and the caecum
2. the corresponding part in insects
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Bariatric procedures performed in patients and tested in animals include bypass of the foregut (duodenal-jejunal bypass (DJB)) [10, 11], bypass of the foregut in combination with partial or total removal of the stomach (Roux-en-Y-gastric biliary bypass (RYGB)) [2], and interposition of a segment of the distal ileum into the proximal jejunum (ileal interposition (IIP)) [12, 13].
The extract on application to the isolated guinea-pig ileum preparations, exhibited a concentration-dependent contractile response at the concentration range of 3-10 mg/mL.
In our case, the first mechanism was the most probable explanation because there were an inlet and outlet injuries of the ileum, and no perforation of the renal pelvis during PCNL.
Extraction from Human Ileum. One ileum sample was extracted per patient.
The previously reported types of hamartomas of the ileal part of small intestine were neuromuscular and vascular hamartoma (NMVH), neuromesenchymal hamartoma (NMH), myoepithelial hamartoma (MEH), and Cowden hamartomatous syndrome Table 1 summarises the reported cases of terminal ileum hamartomas.
calcitonin gene-related polypeptide, and even more compounds including toxic compounds such as barium ions ([Ba.sup.2+]) may be involved in a complex, yet unknown manner leading to ileum contraction and disturbances.
In the evaluation and classification of terminal ileum damage, scoring devised by Ay et al.
Compared to CTR, the pH value in ileum was decreased (p< 0.05) in pigs fed diets supplemented with MOA (MOA1 or MOA2).
SBA is more predominant in duodenum, followed by jejunum and ileum with a diminishing frequency as we go distally.
After the experiment was concluded, the abdomens of rats with an adequate anaesthesia level were opened, 2 mL of blood was taken from the abdominal aorta for the MDA and SCUBE-1 analyses, the right kidney and 4 cm of the ileal tissue from the proximal terminal ileum were removed, then the extracted ileal tissue was washed using cold saline solution.