What is the initial department of the small intestine
circular folds(lat.plicae circulares) are formed by the mucosa and submucosa of the small intestine;
intestinal villi(lat.villi intestinales) are formed by protrusions of the mucous membrane finger-shaped or leaf-shaped, freely protruding into the lumen of the small intestine. The number of villi in the small intestine is very significant: the largest number in the duodenum and jejunum - there are from 22 to 40 villi per one square millimeter of the mucosa. Somewhat less of them in the ileum - from 18 to 31 villi per one square millimeter;
intestinal glandsorcrypts(lat.glandulae seu cryptae intestinales) are represented by tubular indentations located in the own plate of the mucous membrane, and their mouths open into the lumen of the small intestine between the intestinal villi. In this case, one square millimeter of the surface of the mucosa of the small intestine accounts for up to 100 crypts, their total the amount exceeds 150 million intestinal glands throughout the entire length, and the total area of crypts in the small intestine reaches 14 m 2.
Submucoid baseoften contains lobules of adipose tissue. in it there are vessels (arterial, venous, lymphatic) and submucous nervous plexus .
Muscle shellThe small intestine is represented by two layers of muscle cells. more powerful internal (or circular) and less developed external (or longitudinal). In this case, the direction of the muscle fiber bundles in both layers is not strictly longitudinal or circular, but spiral, and the curls of the spiral in the outer layer are more stretched than in the inner layer. Between layers of the muscular shell of the small intestine is located a layer of loose fibrous connective tissue. which contains nodes of the musculoskeletal nerve plexus and vessels. Biological significance (the main function) of the small intestine muscular shell consists in mixing and pushing the chyme along the bowel in the caudal direction. In this case, the muscular contractions of two types are distinguished: abridgments of a local character, performed rhythmically with frequency of 12-13 times per minute, caused mainly by contractions of the inner layer of the muscular membrane and others (peristaltic) contractions caused by the action of the muscular elements of both layers and propagating successively along the entire length of the small intestine. The regulation of muscle contractions is carried out by fibers of the musculoskeletal nerve plexus (Lat.plexus myenteriens): the increase of peristalsis is observed when sympathetic nerves are excited, and the weakening is accompanied by the excitation of the vagus nerve .
Serous membranecovers the small intestine from the outside and from all sides (with the exception of the duodenum, which covered with the peritoneum only in front, and otherwise only connective tissue membrane), forming mesentery .
The structure of the duodenumDuodenum is the initial section of the small intestine, it follows immediately after the pylorus (the gatekeeper of the stomach). Then this section of the intestine goes from left to right and somewhat backward, turns down, descends along the anterior surface of the right kidney, turns to the left and, rising obliquely upwards, passes into the skinny gut. The name of this department of the intestine is related to its length, which is exactly twelve diameters of the fingers of the hand. Anatomy of the duodenum is closely related to the bile excretory system, as well as the pancreas. On the inner surface of the descending section of the duodenum is situated the feces of the papilla (or the large duodenal papilla). Here, through the sphincter of Oddi, the common bile duct opens, the pancreatic duct (in some people, the pancreatic duct can directly flow into the common bile duct). A small duodenal papilla is located 8-40 mm above the large duodenal papilla. An additional pancreatic duct opens through it. This structure is anatomically variable. The histological structure of the mucous membrane of the duodenum provides the stability of its epithelium to the aggressive composition of gastric juice, bile, pancreatic enzymes.Functions of the duodenum Oneof the main functions of the duodenum is to bring the pH of the food gruel coming from the stomach to the alkaline, which will not irritate the distal parts of the intestine and is suitable for the processes of parietal digestion. It is in this section of the intestine that the processes of intestinal digestion begin.Secondan important function of the duodenum is the initiation and regulation of enzymatic activity pancreas and liver, depending on the chemical composition and acidity of the incoming food gruel.The thirdfunction of the duodenum is the regulation of the reflex opening and closing of the pyloric, depending on the acidity and chemical composition of the contents this section of the intestine, as well as the regulation of the acidity of gastric juice due to the secretion of humoral factors that provide secretory activity stomach.
79. Features of the structure of the wall of the large intestine.consists of blindly, bosom and rectum. In it, the absorption of nutrients and water ends, and feces are formed.
The structure of the wall of the large intestine
The mucous membrane, unlike the mucosa of the small intestine, is devoid of circular folds and villi, and the lymphoid tissue forms only single follicles in it. However, the intestinal crypts are deeper, and among the cells of the single-layered cylindrical epithelium there are a lot of goblet cells, the number of which increases towards the rectum (see Fig. Atl.). Therefore, in the large intestines, a lot of mucus-free enzymes are released, which facilitates the progress of undigested food residues. The surface of the cells of the covering epithelium, like in the small intestine, is covered with microvilli. In addition, enteroendocrine cells are found in the epithelium. Migration of cells from the depth of the crypts to the surface of the epithelium occurs as well as in the small intestine.
The part of the rectum adjacent to the anus (anorectal section) is devoid of crypt and is covered with multilayered flat epithelium. It smoothly passes into the epidermis of the skin. The mucous membrane of the anorectal canal forms longitudinal folds or columns. In this area, the muscular plate of the mucosa gradually disappears. Venous plexus is well developed here. With the expansion of these small convoluted veins, the mucous membrane protrudes into the lumen of the intestine, a disease arises - hemorrhoids.
The muscular membrane consists of two layers - inner (circular) and external (longitudinal), which is developed unevenly. Most muscle cells concentrate in three narrowmuscle bands(cm. Atl. ). The parts of the intestine between the ribbons form protrusions - the hauters, separated by transverse furrows, which, on the inside correspond to the semilunar folds. The latter are formed by all the walls of the wall, and not only the mucosa, as in the small intestine
In the rectum, the longitudinal muscular layer is located evenly over the entire wall, and there are no ribbons and protrusions. Circular muscle cells in the anal canal forminternal sphincter.
The serous membrane covers the blind, transverse colonic and upper part of the rectum from all sides, and the ascending and descending colonic on three sides. Sometimes the serous membrane leaves the surface of the intestine, forming outgrowths filled with fat tissue.
The structure of the duodenum
Duodenum is the initial section of the small intestine, it follows immediately after the pylorus (the gatekeeper of the stomach). Then this section of the intestine goes from left to right and somewhat backward, turns down, descends along the anterior surface of the right kidney, turns to the left and, rising obliquely upwards, passes into the skinny gut. The name of this department of the intestine is related to its length, which is exactly twelve diameters of the fingers of the hand.
Anatomy of the duodenum is closely related to the bile excretory system, as well as the pancreas. On the inner surface of the descending section of the duodenum is situated the feces of the papilla (or the large duodenal papilla). Here, through the sphincter of Oddi, the common bile duct opens, the pancreatic duct (in some people, the pancreatic duct can directly flow into the common bile duct). A small duodenal papilla is located 8-40 mm above the large duodenal papilla. An additional pancreatic duct opens through it. This structure is anatomically variable.
The histological structure of the mucous membrane of the duodenum provides the stability of its epithelium to the aggressive composition of gastric juice, bile, pancreatic enzymes.
Functions of the duodenum
One of the main functions of the duodenum is to bring the pH of the food gruel from the stomach to alkaline, which will not irritate the distal parts of the intestine and is suitable for the implementation of processes near-wall digestion. It is in this section of the intestine that the processes of intestinal digestion begin.
The second important function of the duodenum is initiation and regulation of the enzymatic activity of the pancreas and liver, depending on the chemical composition and acidity of the incoming food mush.
The third function of the duodenum is the regulation of the reflex opening and closing of the pyloric, depending on the acidity and chemical composition the content of this part of the intestine, as well as the regulation of the acidity of gastric juice due to the secretion of humoral factors that provide secretory activity of the stomach.
Diseases of the duodenum
The most frequent diseases of the duodenum are duodenal inflammation (duodenitis), duodenal ulcer, cancer (duodenal cancer).
Duodenitis is an inflammation of the duodenum, namely its mucous membrane. The reason for the development of duodenitis is food poisoning, poisoning with toxic substances, which irritate the mucous GASTROINTESTINAL TRACT, excessive use of spicy food, especially in combination with alcohol, damage to mucous membranes by foreign bodies.
For inflammation of the duodenum, symptoms are such as epigastric pain, weakness, nausea, vomiting, fever. The catarrhal and erosive-ulcerative form of duodenitis usually ends within a few days with self-healing, with repeated injury, the process can be chronized. The complications of duodenitis include the development of acute pancreatitis, intestinal bleeding, perforation of the wall of the duodenum.
Treatment duodenitis consists of adequate dietotherapy, the use of astringent and enveloping drugs, antispasmodics and anticholinergics.
Duodenal ulcer develops as a result of the action of Helicobacter pylori infection. Predispose to the development of this pathology of hereditary factors, neuropsychic features of man, food factor, the effect of drugs, bad habits. Symptoms of this disease are pain in the epigastrium a few hours after eating, night epigastric pain, heartburn, nausea, vomiting. Complications of the disease include bleeding, penetration, malignancy (malignant development), stenosis of the pylorus, as well as perforation of the wall of the duodenum.
Treatment consists in taking anti-Helicobacter pills (antibiotics, bismuth preparations), symptomatic therapy, diet therapy.
Cancer of the duodenum
Cancer of the duodenum is most often localized in the papillose region (descending section), more rarely in the upper or lower horizontal part. Duodenal cancer, unlike gastric cancer, is characterized by a low propensity to form metastases. Usually limited to regional lymph nodes. A feature of the clinical picture of duodenal cancer is that the tumor of small sizes does not give symptoms, since it does not hinder the passage of intestinal contents and does not cause intoxication. Consequently, the symptoms occur with a sufficient increase in the tumor and compression of a number of located organs. There are symptoms associated with difficult entry of bile into the intestine: pain in the right upper quadrant, nausea, decreased appetite. When the pancreatic duct is compressed, pancreatitis of varying severity develops. In large tumors, the clinic is associated with stenosis: nausea, bloating, stomach overflow, eructation, heartburn. Characteristic of such a common symptom, such as weight loss, anemia, anorexia. Successful treatment depends on the timely diagnosis of duodenal cancer. Treatment of this pathology is operative - circular resection of the affected part of the intestine, with peripapillary cancer also removes the large duodenal papilla, the pancreatic duct.
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the initial department of the small intestine is 1 esophagus 2 duodenum 3 gallbladder 4 caecum
the initial department of the small intestine is 1 esophagus 2 duodenum 3 gallbladder 4 caecum
- 12 fingers to.
- 12 duodenum
The stomach follows the next section of the digestive tract, the small intestine. The small intestine has a length of up to five meters and consists of three sections: duodenum, jejunum and ileum. The entire small intestine is divided into two parts: the duodenum and the mesenteric part of the small intestine, which forms a number of loops.
The duodenum starts right after the pyloric sphincter, it has the shape of a horseshoe that wraps around the pancreas. There are three parts of the pancreas: the upper, the descending and the horizontal. On the mucosa of the duodenum there is a tubercle, on top of which the pancreatic duct and the common bile duct open.
Behind the duodenum, which ends at the level of the first second lumbar vertebra, the mesenteric part of the small intestine begins, the initial part of which is the jejunum. The jejunum has a length of, m, and without visible boundaries passes into the iliac, which ends with an ileocecal valve located at the site of the small intestine passing into the thick one.
The wall of the large intestine consists of the mucous membrane, submucosal and muscular layers, and also the serous membrane.
The mucosa of the small intestine is represented by the epithelium containing.
Columnar cells form villi, which covers the entire mucosa of the small intestine, and also produce enzymes and participate in the transport of substances.
Goblet cells produce parietal mucus and bactericidal substances.
Penet cells produce lysozyme and other bactericidal substances that provide protection from pathogenic microflora.
M-cells are involved in the recognition of pathogens and their particles, and activate lymphocytes.
In the submucosal layer of the small intestine, blood and lymphatic vessels pass, and intestinal glands and areas of the lymphoid tissue (Peyrov's plaques and solitary follicles) are located.
The muscular membrane of the small intestine is represented by two layers of smooth muscles: longitudinal and circular, the contractions of which promote the progress of the chyme and its mixing.
The following departments are distinguished in the small intestine:
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Sources: http://www.studfiles.ru/preview/5808598/pag: 4/, http://www.neboleem.net/dvenadcatiperstnaja-kishka.php, http://foksokol.ru/nachalnim-otdelom-tonkogo-kishechnika-yavlyaetsya-1-pishevod-2-dvenadcatiperstnaya-kishka-3-zhelchnij-puzir-4-slepaya-kishka/
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