small intestine

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small intestine:

see intestineintestine,
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.
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Intestine, Small


the portion of the gut of vertebrate mammals, including man, that is situated between the stomach and the large intestine. The final digestion of food, the absorption of nutrients, and the movement of chyme occur in the small intestine.

In mammals, including man, the small intestine is divided into three sections: the duodenum, the jejunum, and the ileum. The length of the small intestine differs according to the nature of the digestive process: in man it is 6–7 m long, in cattle 27–49 m, in dogs 1.8–4.8 m, in cats 0.8–1.3 m, and in swine 16–21 m. In man the diameter of the small intestine is 48 mm in the initial section and 27 mm at the place where the ileum empties into the large intestine.

The walls of all sections of the small intestine are composed of mucous, submucous, and serous membranes and a muscular coat. Each section varies in the microscopic and submicroscopic characteristics of the intestinal wall, which reflect differences in function. The surface area of the small intestine’s mucous membrane is greatly increased by folds and protuberances: examples are the spiral valve in the mucous membrane of some fishes, and the villi, folds, and crypts in the small intestine of birds, mammals, and man.

Food is digested both in the intestinal cavity itself and by means of membrane-mediated (parietal) digestion. Cavitary digestion is achieved by the flow of pancreatic juice, bile, and intestinal juice into the lumen of the small intestine. During this process, supramolecular aggregates and the large molecules of proteins, carbohydrates, and fats in the food mass are hydrolyzed by the proteolytic, amylolytic, and lipolytic enzymes in the small intestine. The products of intermediate hydrolysis are adsorbed on the surface of the mucous membrane of the small intestine, where the final stages of hydrolysis and transition to absorption take place.

Parietal digestion is achieved by means of enzymes that are structurally bound to the cell membranes of the intestinal epithelium. The digestion and absorption of food in the small intestine are accompanied by contractions of the intestinal walls that mix and stir the chyme and propel it through the intestine.


small intestine

[′smȯl in′tes·tən]
The anterior portion of the intestine in humans and other mammals; it is divided into three parts, the duodenum, the jejunum, and the ileum.

small intestine

the longest part of the alimentary canal, consisting of the duodenum, jejunum, and ileum, in which digestion is completed
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8, the nucleo-apical distance in all small intestinal segments changed little as the dosages of sodium caprate and water-soluble chitosan were added, although there was a remarkable decrease on the nucleo-apical distance after administrating orally 200 mg/kg Triton X-100 as a positive control.
Use of small intestinal sub mucosa implants for regeneration of large fascial defects; an experimental study in dogs.
Eventually, the small intestinal submucosa scaffold is completely remodeled away, and the new tissue reaches the strength of the original ligament.
Small Intestinal Bacterial Overgrowth: Correlation of SIBO and Rosacea
Gain-of-function PDGFRA mutations, earlier reported in gastrointestinal stromal tumors, are common in small intestinal inflammatory fibroid polyps: astudy of 60 cases.
Interestingly, there was a breed effect on the small intestinal morphology in the ileum, while there were no breed related differences in the duodenum and jejunum.
Metastasis of small intestinal leiomyosarcoma was most common (eight cases).
It inhibited castor-oil-stimulated small intestinal transit 60 min after administration.
Celiac sprue is definitively diagnosed by small intestinal biopsy, but the serologic test for IgA antibody against tissue transglutaminase is extremely accurate.
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This process is referred to as small intestinal bacterial overgrowth (SIBO), which results in gas, bloating, abdominal pain and altered stool habits characterized by IBS.
Association belwwn hypothyroidism and small intestinal bacterial overgrowth.

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