intestine

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 appendixappendix,
small, worm-shaped blind tube, about 3 in. (7.6 cm) long and 1-4 in. to 1 in. (.64–2.54 cm) thick, projecting from the cecum (part of the large intestine) on the right side of the lower abdominal cavity.
..... Click the link for more information. , 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 systemdigestive system,
in the animal kingdom, a group of organs functioning in digestion and assimilation of food and elimination of wastes. Virtually all animals have a digestive system. In the vertebrates (phylum Chordata, subphylum Vertebrata) the digestive system is very complex.
..... Click the link for more information. .

Intestine

The tubular portion of the digestive tract, usually between the stomach and the cloaca or anus. The detailed functions vary with the region, but are primarily digestion and absorption of food.

The structure of the intestine varies greatly in different vertebrates, but there are several common modifications, mainly associated with increasing the internal surface area. One, seen in many fishes, is the development of a spiral valve; this turns the intestine into a structure resembling a spiral staircase. Another, seen in some fish and most tetrapods, is simply elongating and then coiling the intestine. This can reach extremes in large herbivores: Oxen have intestinal lengths of over 150 ft (45 m). In numerous forms there are blind pouches, or ceca, off part of the intestine. In fish these are commonly at the anterior end; in tetrapods they generally lie at the junction between the large and small intestines. In all vertebrates the inner surface of the intestine is irregular, with ridges and projections of various sorts; these reach their maximum development in the extremely fine and numerous finger-shaped villi found in mammals.

In humans the intestine consists of the small and large intestines. The small intestine is further divided into three major parts: the duodenum, the jejunum, and the ileum. The duodenum, 10–12 in. (25–30 cm) long, begins at the pyloric sphincter of the stomach and curves around the head of the pancreas on the right side of the anterior part of the abdomen. It receives the ducts of the biliary system and the pancreas. The jejunum and ileum are about 19 ft (6 m) long and form a much-coiled tube that empties at right angles into the large intestine through the ileocolic valve (see illustration). The large intestine, or colon, consists of five parts: the ascending, transverse, descending, and sigmoid regions, and the terminal rectum which empties into the anal canal.

Junction of ileum with large intestine in humans

The microscopic structure of the intestine comprises an inner glandular mucosa, a muscular coat, and an outer serosa of connective tissues which is covered in most areas by peritoneum.

The intestine is supported by dorsal mesenteries of varying extent, which contain an extensive system of arteries, veins, lymphatics, and nerves to the various regions. See Digestive system

intestine

[in′tes·tən] (anatomy) The tubular portion of the vertebrate digestive tract, usually between the stomach and the cloaca or anus.

intestine

the part of the alimentary canal between the stomach and the anus

intestine

[in-tes´tin] the part of the alimentary canal" >alimentary canal extending from the pyloric opening of the stomach to the anus. It is a membranous tube, comprising the small intestine and large intestine; called also bowel and gut. See also intestinal tract, and see color plates.

in·tes·tine

(in-tes'tin), [TA] The digestive tube passing from the stomach to the anus. It is divided primarily into the small intestine (intestinum tenue) and the large intestine (intestinum crassum). Synonym(s): bowel, gut (1) , intestinum (1) [L. intestinum]

intestine

(ĭn-tĕs′tĭn)n. often intestines The portion of the digestive tract extending from the stomach to the anus and, in humans and other mammals, consisting of two segments, the small intestine and the large intestine.adj. Internal; civil: the intestine affairs of the nation.

in·tes·tine

(in-tes'tin) [TA] 1. The digestive tube passing from the stomach to the anus. It is divided primarily into the intestinum tenue (small intestine) and the intestinum crassum (large intestine). 2. Inward; inner.
Synonym(s): intestinum [TA] , bowel, gut (1) . [L. intestinum ]

intestine

(in-tes'tin) [L. intestinum] The portion of the alimentary canal that extends from the pylorus of the stomach to the anus. It includes the duodenum, jejunum, ileum (small intestine), and colon (large intestine) and is responsible for the completion of digestion and the absorption of nutrients and water. Synonym: bowel; gut (1) See: abdomen

SMALL INTESTINE: (duodenum, jejunum, ileum)

LARGE INTESTINE

large intestine

The large intestine extends from the ileum to the anus and is about 1.5 m (5 ft) in length. It absorbs water, minerals, and vitamins from the intestinal contents and eliminates undigested material during defecation. The mucosa has no villi but contains glands that secrete mucus. Hyperactivity of the colon may cause diarrhea. See: illustration

The first part of the large intestine is the cecum, a pouch on the right side into which the ileum empties. Attached to the cecum is the vermiform appendix, about 7.5 to 10.4 cm (3 to 4 in) long. The ascending colon extends from the cecum upward to the undersurface of the liver, where it turns left (hepatic flexure) and becomes the transverse colon, which continues toward the spleen and turns downward (splenic flexure) to become the descending colon. At the level of the pelvic brim, the descending colon turns inward in the shape of the letter S and is then called the sigmoid colon. The rectum, about 10.2 to 12.7 cm (4 to 5 in) long, is the straight part that continues downward; the last 2.5 cm (1 in) is called the anal canal, which surrounds the anus.

illustration

small intestine

The first part of the small intestine is the duodenum, approx. 8 to 11 in (20 to 28 cm) long, which receives chyme from the stomach through the pyloric orifice and, by way of the common bile duct, bile from the liver and gallbladder, and pancreatic juice from the pancreas. The second part is the jejunum, about 9 ft (2.8 m) long. The third part is the ileum, about 13 ft (4 m) long. The ileum opens into the cecum of the large intestine, and the ileocecal valve prevents backup of intestinal contents.

The wall of the small intestine has circular folds (plicae circulares), which are folds of the mucosa and submucosa that look like accordion pleats. The mucosa is further folded into villi, which look like small (0.5 to 1.5 mm long) projections. The free surfaces of the epithelial cells have microscopic folds called microvilli that are collectively called the brush border. All of the folds increase the surface area for absorption of the end products of digestion. Intestinal glands (of Lieberkühn) between the bases of the villi secrete enzymes. The duodenum has submucosal Brunner's glands that secrete mucus. Enzymes secreted by the small intestine are peptidases, which complete protein digestion, and sucrase, maltase, and lactase, which digest disaccharides to monosaccharides. Some of these enzymes function in the brush border rather than in the lumen of the intestine. Hormones secreted by the duodenum are gastric inhibitory peptide, secretin, and cholecystokinin; these influence secretions or motility of other parts of the digestive tract.

The end products of digestion (amino acids, monosaccharides, fatty acids, glycerol, vitamins, minerals, and water) are absorbed into the capillaries or lacteals within the villi. Blood from the small intestine passes through the liver by way of the portal vein before returning to the heart.

See: duodenum; liver; pancreas

intestine

The part of the digestive system lying between the outlet of the stomach (the PYLORUS) and the ANUS. It consists, sequentially, of the DUODENUM, the JEJUNUM, the ILEUM, the wide, pouch-like caecum, that carries the APPENDIX, the large intestine, or COLON, the S-shaped SIGMOID colon, the RECTUM and anus.

intestine

the part of the alimentary canal that lies between the stomach and the anus. Usually it is coiled and the internal surface is greatly increased by the presence of folds and projections (VILLI) to allow efficient digestion and absorption. Anteriorly, the intestine is lined with an EPITHELIUM containing ENZYME and MUCUS-secreting glands, and in higher vertebrates it is referred to as the SMALL INTESTINE. The posterior, large intestine, dehydrates the faeces which are stored here until voided in DEFECATION.

Intestine

Also called the bowels and divided into large and small intestine, they extend from the stomach to the anus, where waste products exit the body. The small intestine is about 20 ft (6.1m) long and the large intestine, about 5 ft (1.5m) long.Mentioned in: Colostomy, Enemas

Patient discussion about intestine

Q. I recently had my surgery for bowel obstruction? I recently had my surgery for bowel obstruction? None of the diet was restricted for me by doctor but should I go for any special diet.A. I had surgery in 08/08 during having a c-section and hernia repair, and I'm having diarrhea all the time. I don't know what to eat nor what medicines to take. Only Immodium AD helps temporary. If I have an appointment, I don't eat breakfast or lunch. I come home and eat dinner. About 30 minutes after eating, I'm in the bathroom. Can someone help me please? I have to return back to work next month, and I don't want to be in the bathroom more than I am at my desk.

Q. Can Alcoholism makes you vulnerable to intestine infections? A friend of mine is a heavy drinker, he had something like 5 infections in the past year. Is it connected?A. yes

Q. What is the connection between bowel disease and arthritis? My son suffers from ulcerative colitis, and the doctor said that his recent joint pain can be as a result of the colitis. Why is that?A. Although ulcerative colitis happens mainly in the colon, it is a systemic disease, and patients may present with symptoms and complications outside the colon. These include musculoskeletal complications such as arthritis (for instance- ankylosing spondylitis). The exact mechanism of this injury is unknown.

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Patient discussion about intestine

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Synonyms for intestine

noun the part of the alimentary canal between the stomach and the anus

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