home Analyzes Anatomy of the stomach. Structure and functions of the human stomach. Functions of the stomach and structure Microscopic structure of the stomach

Anatomy of the stomach. Structure and functions of the human stomach. Functions of the stomach and structure Microscopic structure of the stomach

The normal residence time of the contents (digested food) in the stomach is about 1 hour.

Anatomy of the stomach

Anatomically, the stomach is divided into four parts:

cardiac(lat. pars cardiaca), adjacent to the esophagus;
pyloric or gatekeeper (lat. pars pylorica), adjacent to the duodenum;
body of stomach(lat. corpus ventriculi), located between the cardiac and pyloric parts;
fundus of the stomach(lat. fundus ventriculi), located above and to the left of the cardiac part.

In the pyloric region there are gatekeeper cave(lat. antrum pyloricum), synonyms antrum or anturm and channel gatekeeper(lat. canalis pyloricus).

The figure on the right shows: 1. Body of the stomach. 2. Fundus of the stomach. 3. Anterior wall of the stomach. 4. Greater curvature. 5. Small curvature. 6. Lower esophageal sphincter (cardia). 9. Pyloric sphincter. 10. Antrum. 11. Pyloric canal. 12. Corner cut. 13. A groove formed during digestion between the longitudinal folds of the mucosa along the lesser curvature. 14. Folds of the mucous membrane.

The following anatomical structures are also distinguished in the stomach:

anterior wall of the stomach(lat. paries anterior);
posterior wall of the stomach(lat. paries posterior);
lesser curvature of the stomach(lat. curvatura ventriculi minor);
greater curvature of the stomach(lat. curvatura ventriculi major).

The stomach is separated from the esophagus by the lower esophageal sphincter and from the duodenum by the pyloric sphincter.

The shape of the stomach depends on the position of the body, the fullness of food, and the functional state of the person. With average filling, the length of the stomach is 14–30 cm, width 10–16 cm, length of the lesser curvature 10.5 cm, greater curvature 32–64 cm, wall thickness in the cardiac region 2–3 mm (up to 6 mm), in the antrum 3 –4 mm (up to 8 mm). The stomach capacity is from 1.5 to 2.5 liters (the male stomach is larger than the female). The normal weight of the stomach of a “conditional person” (with a body weight of 70 kg) is 150 g.

The stomach wall consists of four main layers (listed from the inner surface of the wall to the outer):

mucous membrane covered with single-layer columnar epithelium
submucosa
muscle layer, consisting of three sublayers of smooth muscle:

inner sublayer of oblique muscles
middle sublayer of circular muscles
outer sublayer of longitudinal muscles

serous membrane.

Between the submucosa and the muscle layer is the Meissner nerve (synonym for submucosa; lat. plexus submucosus) plexus that regulates the secretory function of epithelial cells between the circular and longitudinal muscles - Auerbach's (synonym intermuscular; lat. plexus myentericus) plexus.

Stomach mucosa

The mucous membrane of the stomach is formed by a single layer of columnar epithelium, a layer of its own and a muscular plate that forms folds (relief of the mucous membrane), gastric fields and gastric pits, where the excretory ducts of the gastric glands are localized. In the proper layer of the mucous membrane there are tubular gastric glands, consisting of parietal cells that produce hydrochloric acid; main cells producing the proenzyme pepsin pepsinogen, and accessory (mucosal) cells secreting mucus. In addition, mucus is synthesized by mucous cells located in the layer of the surface (integumentary) epithelium of the stomach.

The surface of the gastric mucosa is covered with a continuous thin layer of mucous gel consisting of glycoproteins, and underneath is a layer of bicarbonates adjacent to the superficial epithelium of the mucosa. Together they form the mucobicarbonate barrier of the stomach, which protects epithelial cells from the aggression of the acid-peptic factor (Y.S. Zimmerman). The mucus contains immunoglobulin A (IgA), lysozyme, lactoferrin and other components with antimicrobial activity.

The surface of the mucous membrane of the body of the stomach has a pitted structure, which creates conditions for minimal contact of the epithelium with the aggressive intracavitary environment of the stomach, which is also facilitated by a thick layer of mucous gel. Therefore, the acidity on the surface of the epithelium is close to neutral. The mucous membrane of the body of the stomach is characterized by a relatively short path for the movement of hydrochloric acid from the parietal cells into the lumen of the stomach, since they are located mainly in the upper half of the glands, and the main cells are in the basal part. An important contribution to the mechanism of protecting the gastric mucosa from the aggression of gastric juice is made by the extremely rapid nature of gland secretion, caused by the work of the muscle fibers of the gastric mucosa. On the contrary, the mucous membrane of the antral region of the stomach (see the figure on the right) is characterized by a “villous” structure of the surface of the mucous membrane, which is formed by short villi or convoluted ridges 125–350 µm high (Lysikov Yu.A. et al.).

Stomach in children

In children, the shape of the stomach is not constant and depends on the constitution of the child’s body, age and diet. In newborns, the stomach has a round shape; by the beginning of the first year it becomes oblong. By the age of 7–11, a child’s stomach does not differ in shape from an adult’s. In infants, the stomach is positioned horizontally, but as soon as the child begins to walk, it takes on a more vertical position.

By the birth of a child, the fundus and cardiac part of the stomach are not sufficiently developed, and the pyloric part is much better, which explains frequent regurgitation. Regurgitation is also promoted by swallowing air during sucking (aerophagia), with improper feeding technique, short frenulum of the tongue, greedy sucking, and too rapid release of milk from the mother's breast.

Gastric juice

The main components of gastric juice are: hydrochloric acid secreted by parietal cells, proteolytic enzymes produced by chief cells and non-proteolytic enzymes, mucus and bicarbonates (secreted by accessory cells), intrinsic Castle factor (production of parietal cells).

The gastric juice of a healthy person is practically colorless, odorless and contains a small amount of mucus.

Basal secretion, not stimulated by food or otherwise, in men is: gastric juice 80-100 ml/h, hydrochloric acid - 2.5-5.0 mmol/h, pepsin - 20-35 mg/h. Women have 25–30% less. About 2 liters of gastric juice are produced in the stomach of an adult per day.

The gastric juice of an infant contains the same components as the gastric juice of an adult: rennet, hydrochloric acid, pepsin, lipase, but their content is reduced, especially in newborns, and increases gradually. Pepsin breaks down proteins into albumins and peptones. Lipase breaks down neutral fats into fatty acids and glycerol. Rennet (the most active enzyme in infants) curdles milk (Bokonbaeva S.D. et al.).

Stomach acidity

The main contribution to the total acidity of gastric juice is made by hydrochloric acid produced by the parietal cells of the fundic glands of the stomach, located mainly in the area of the fundus and body of the stomach. The concentration of hydrochloric acid secreted by parietal cells is the same and equal to 160 mmol/l, but the acidity of the secreted gastric juice varies due to changes in the number of functioning parietal cells and neutralization of hydrochloric acid by alkaline components of gastric juice.

Normal acidity in the lumen of the body of the stomach on an empty stomach is 1.5–2.0 pH. The acidity on the surface of the epithelial layer facing the lumen of the stomach is 1.5–2.0 pH. The acidity in the depths of the epithelial layer of the stomach is about 7.0 pH. Normal acidity in the antrum of the stomach is 1.3–7.4 pH.

Currently, the only reliable method for measuring gastric acidity is intragastric pH-metry, performed using special devices - acidogastrometers, equipped with pH probes with several pH sensors, which allows you to measure acidity simultaneously in different areas of the gastrointestinal tract.

Stomach acidity in relatively healthy people (who do not have any subjective gastroenterological sensations) changes cyclically during the day. Daily fluctuations in acidity are greater in the antrum than in the body of the stomach. The main reason for such changes in acidity is the longer duration of nocturnal duodenogastric reflux (DGR) compared to daytime, which throws duodenal contents into the stomach and, thereby, reduces the acidity in the lumen of the stomach (increases pH). The table below shows the average acidity values in the antrum and body of the stomach in apparently healthy patients (Kolesnikova I.Yu., 2009):

The general acidity of gastric juice in children of the first year of life is 2.5–3 times lower than in adults. Free hydrochloric acid is determined during breastfeeding after 1–1.5 hours, and during artificial feeding – after 2.5–3 hours after feeding. The acidity of gastric juice is subject to significant fluctuations depending on the nature and diet, and the state of the gastrointestinal tract.

Gastric motility

In terms of motor activity, the stomach can be divided into two zones: proximal (upper) and distal (lower). There are no rhythmic contractions or peristalsis in the proximal zone. The tone of this zone depends on the fullness of the stomach. When food arrives, the tone of the muscular lining of the stomach decreases and the stomach reflexively relaxes.

Motor activity of various parts of the stomach and duodenum (Gorban V.V. et al.)

The figure on the right shows a diagram of the fundic gland (Dubinskaya T.K.):

1 - mucus-bicarbonate layer
2 - superficial epithelium
3 - mucous cells of the neck of the glands
4 - parietal (parietal) cells
5 - endocrine cells
6 - main (zymogenic) cells
7 - fundic gland
8 - gastric pit

Microflora of the stomach

Until recently, it was believed that due to the bactericidal effect of gastric juice, microflora that penetrated the stomach died within 30 minutes. However, modern methods of microbiological research have proven that this is not the case. The amount of various mucosal microflora in the stomach of healthy people is 10 3 –10 4 / ml (3 lg CFU / g), including those detected in 44.4% of cases Helicobacter pylori(5.3 lg CFU/g), 55.5% - streptococci (4 lg CFU/g), 61.1% - staphylococci (3.7 lg CFU/g), 50% - lactobacilli (3. 2 lg CFU/g), in 22.2% - fungi of the genus Candida(3.5 lg CFU/g). In addition, bacteroides, corynebacteria, micrococci, etc. were sown in an amount of 2.7–3.7 lg CFU/g. It should be noted that Helicobacter pylori were determined only in association with other bacteria. The environment in the stomach turned out to be sterile in healthy people only in 10% of cases. Based on their origin, the microflora of the stomach is conventionally divided into oral-respiratory and fecal. In 2005, strains of lactobacilli that adapted (similar to Helicobacter pylori) to exist in the sharply acidic environment of the stomach: Lactobacillus gastricus, Lactobacillus antri, Lactobacillus kalixensis, Lactobacillus ultunensis. In various diseases (chronic gastritis, peptic ulcer, stomach cancer), the number and diversity of bacterial species colonizing the stomach increases significantly. In chronic gastritis, the largest amount of mucosal microflora is found in the antrum, and in peptic ulcers - in the periulcerous zone (in the inflammatory ridge). Moreover, the dominant position is often occupied by non- Helicobacter pylori, and streptococci, staphylococci,

>> what is a stomach?

(lat. ventriculus, gaster) is a hollow organ of the digestive tract in which accumulation and partial digestion of food occurs.

Anatomical characteristics of the stomach
The entire gastrointestinal tract can be imagined as a pipe approximately 7-8 m long. The upper sections of the digestive tract are represented by the oral cavity, pharynx, esophagus, stomach and the initial section of the small intestine (duodenum), the lower sections are a continuation of the small intestine (jejunum and ileum ), as well as the large intestine with its end section - the rectum. As food passes through the various sections of this tube, it undergoes various changes - digestion and absorption. The stomach is a pouch-shaped extension of the digestive tube located between the esophagus and duodenum. Food from the mouth enters the stomach through the esophagus. From the stomach, partially digested food masses are excreted into the duodenum (the initial section of the small intestine).

The site provides reference information for informational purposes only. Diagnosis and treatment of diseases must be carried out under the supervision of a specialist. All drugs have contraindications. Consultation with a specialist is required!

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(ventriculus, gaster) - the most expanded part of the digestive tube. The distance from the incisors to the stomach is approximately 40 cm, which is taken into account when probing it. The stomach has the appearance of a curved sac (see Atl.), asymmetrically located in the peritoneal cavity: most of it (5/6) is on the left, and the smaller part (1/6) is on the right of the median plane of the body. The long axis of the stomach is directed from above to the left and from behind to the right, below and forward. The convex edge of the stomach - greater curvature- facing to the left and partially downwards and adjacent to the mesentery of the transverse colon; short concave edge - small curvature - turned to the right and upward (see Atl.). At the upper left end of the lesser curvature, at the level of the XI thoracic vertebra, the esophagus opens into the stomach. The part of the stomach surrounding the opening of the esophagus is called cardiac. The right end of the lesser curvature limits pylorus. It is noticeable in the form of an interception corresponding to the position of the circular muscular valve, which lies on the border of the stomach and duodenum. The spleen, pancreas and left kidney are adjacent to the stomach.

Structure of the stomach

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In the stomach there are the fundus (vault), body and pyloric part (Fig. 4.11, A).

Bottom (vault)

The bottom (vault) is located to the left and slightly higher from the confluence of the esophagus and is separated from it by the cardiac notch. The convexity of the bottom is adjacent to the left dome of the diaphragm. X-rays show an air bubble in this part of the stomach (Fig. 4.11, B).

Rice. 4.11. Stomach:
A - front view, without the serous membrane and with exposed layers of the muscular layer; 1 - abdominal part of the esophagus; 2 - area of entrance to the stomach; 3 - gatekeeper; 4 - greater curvature; 5 — lesser curvature, 6 — arch; 7 - body of the stomach; 8 - longitudinal layer of the muscular membrane (almost the entire length of the stomach has been removed); 9 - layer of circular muscles (removed in two places); 10 - layer of oblique muscles;
B - X-ray of the stomach with average filling with contrast mass, XII - twelfth rib; III - third lumbar vertebra. The arrow points to a gas bubble in the stomach.

Body

The body occupies an almost vertical position, slightly oblique to the median plane, and is partially adjacent to the anterior abdominal wall. The bottom and body are combined into fundamental Department.

Gatekeeper part

The pyloric part, covered by the lower edge of the liver, bends, extends to the right beyond the median plane, turns upward and rises to the level of the first lumbar vertebra, where the pylorus is located.

The area of entry into the stomach is attached by ligaments to the diaphragm, and the pyloric part is attached to the posterior abdominal wall; the remaining sections are mobile and can shift within quite significant limits depending on the degree of filling of the organ. The lower border of the stomach, with strong filling, can drop to the level of the navel; with average filling, it lies 7-10 cm above it. The capacity of the stomach varies and on average reaches 3 liters.

Stomach shape

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The shape of the stomach is also very variable. It depends not only on the degree of filling of the organ and the tone of its walls, but also on the position of the body, fatness, physique and age of the person. The most common forms of the stomach are in the form of a horn, hook or stocking. The shape of the stomach on a corpse, usually compared to a chemical retort, differs sharply from its shape in a living person with the body in an upright position. In a living person, changes in the shape of the stomach can be examined X-ray after filling it with a contrast mass. Stomach capacity differs between men and women - 2.3 liters and 1.9 liters, respectively. In women it occupies a slightly more oblique position than in men.

The structure of the stomach wall

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Stomach wall , like other parts of the gastrointestinal tract, it consists of four layers.

Mucous membrane

The mucous membrane forms a large number of folds (Fig. 4.12), which, as the stomach fills, straighten out and even completely smooth out.

Rice. 4.12. Stomach mucosa

Rice. 4.12. Gastric mucosa:
1 - folds of the mucous membrane;
2 - mucous membrane;
3 - muscular layer;
4 - pyloric opening;
5 - pyloric sphincter muscle;
6 - cardial opening;
7 - mucous membrane of the esophagus

The surface of the mucous membrane is covered with a single-layer prismatic epithelium, the cells of which produce mucus and form numerous depressions - gastric pits(Fig. 4. 13.) Excretory ducts open at the bottom of the pits tubular glands(up to 100 per 1 mm 2). In different parts of the stomach, the glands differ in structure and cellular composition (see Atl). In the cardiac section, the secretory sections of the glands are small and consist mainly of cells that secrete mucus. Scattered among them are single cells that form pepsin.

Rice. 4.13. Gastric mucosa (scanning microscopy)

The glands of the fundus (bottom and body) of the stomach are much larger; they produce the enzymes hydrochloric acid. Depending on the composition of the secretion, the cell structure is different. The cells that secrete pepsinogen are called principal cells. The endoplasmic reticulum and Golgi apparatus are well developed in them. In the stomach cavity, pepsinogen reacts with hydrochloric acid and turns into pepsin. Hydrochloric acid is produced by parietal cells, which are much larger than the main cells. Their distinctive feature is also the presence of tubules through which secretions are released. Hydrochloric acid also has an antimicrobial effect. Almost all microbes that enter the stomach with food die. In the apical part of the gland there are mucous cells. Mucus protects the surface of the stomach from the damaging effects of acid. When the wall layer of mucus is disrupted, the wall cells are damaged, ulcers and inflammation form. This is observed under the influence of toxic substances, alcohol, and stress. However, the cells of the mucous membrane have a high ability to regenerate: they are renewed every three days. In addition, the glands contain single neuroendocrine cells. Their secretion (serotonin, endorphins) is released through the basement membrane surrounding the gland into the lamina propria of the mucous membrane, and from there enters the bloodstream.

The glands of the pyloric region are less deep and more branched than in the fundus of the stomach. Their gastric pits are more pronounced. The epithelium of the pits and the initial part of the glands contains cells that secrete mucus. Parietal cells are rare, so the contents of this part of the stomach are slightly acidic. Endocrine cells located here secrete gastrin and somatostatin. Gastrin stimulates the secretion of hydrochloric acid by the parietal cells of the gastric glands.

In the spaces between the glands there are thin layers of loose connective tissue and few lymphatic follicles (at the junction of the stomach and duodenum). The muscular plate of the mucous membrane is formed by circular and longitudinal layers of muscle cells. Individual cells extend from the plate and are located between the glands. Their reduction helps remove the secretions of these glands.

Submucosa

The submucosa consists of loose connective tissue with plexuses of blood and lymphatic vessels and a submucosal nerve plexus.

Muscularis

The muscularis propria consists of three layers (Fig. 4.14).

Rice. 4.14. Muscular lining of the stomach

4.14. Muscular lining of the stomach: arrangement of muscle layers:

1 - longitudinal muscle layer;
2 - circular muscle layer;
3 - layer of oblique muscle fibers

In addition to the outer longitudinal layer and the following circular layer of smooth muscle tissue, there is also an internal oblique layer, characteristic of the digestive tract only to the stomach and consisting of fibers fan-shaped diverging from the cardiac part to the greater curvature. The circular layer towards the outlet of the stomach intensifies and forms sphincter gatekeeper. It regulates the passage of portions of partially digested food gruel from the stomach to the duodenum. In the sphincter area, the mucous membrane forms a transverse fold. Peristaltic contractions of the muscles of the stomach wall begin in the body region and spread to the pyloric part. At the same time, the food gruel is mixed and it is ensured that it adheres tightly to the wall of the stomach. The liquid, well-ground part of the food (chyme) flows into the pyloric section of the stomach and passes through the sphincter into the duodenum. Larger particles of the bolus remain in the stomach.

Serosa

The serous membrane of the stomach is represented by the visceral peritoneum.

From the diaphragm, the peritoneum descends to the esophagus and the fundus of the stomach in the form of the diaphragmatic-esophageal phrenic-gastric ligaments. The layers of peritoneum covering it from the anterior and posterior surfaces converge on the greater curvature of the stomach. From here they pass in the form of ligaments to neighboring organs, forming gastrosplenic And gastrocolic ligament And big seal. The latter hangs down like an apron and covers the intestine in front (see Atl.), and then turns back upward and fuses with the transverse colon and its mesentery. Well-fed people have significant accumulations of adipose tissue in the greater omentum. Starts from the small curvature gastrohepatic ligament- Part small omentum.

Blood supply to the stomach

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The blood supply to the stomach comes from the right and left gastric and gastroepiploic arteries. The stomach is innervated by the nerves of the autonomic nervous system, which form the subserosal, intermuscular and submucosal nerve plexuses in its wall.

Proteins and partly fats are digested in the stomach. Having lingered in this organ for a certain period of time, the food gruel is sent to the intestines.

The stomach (ventriculus s. gaster) serves as a container for food and prepares it for digestion. Under the influence of gastric juice, food particles are loosened and saturated with digestive enzymes. Many microorganisms that enter the stomach cavity die under the influence of gastric juice. When the muscles of the stomach contract, the food gruel is subjected to mechanical processing and then evacuated to the next sections of the digestive system. It has been established that the mucous membrane produces a special substance that stimulates hematopoiesis (Castle factor).

The stomach is divided into the cardiac part, the fundus, the body and the pyloric part (Fig. 230).

The cardiac part (pars cardiaca) is relatively small, located at the entry of the esophagus into the stomach, and corresponds to the XI thoracic vertebra. When the esophagus flows into the stomach, there is a cardiac opening (ostium cardiacum). The cardiac part on the left is delimited from the vault of the stomach by the notch (incisura cardiaca).

The fundus ventriculi is the highest part of the stomach and is located on the left under the diaphragm. There is always an accumulation of air in it.

The body of the stomach (corpus ventriculi) occupies its middle part.

The pyloric part (pars pylorica) starts from the angular notch (incisura angularis), located on the lesser curvature, and ends with the pyloric sphincter (m. sphincter pylori). In the pyloric part, three sections are distinguished: the vestibule (vestibulum pylori), the cave (antrum pyloricum), and the canal (canalis pyloricus). Vestibulum pylori is located in the initial section of the pyloric part, and then passes into the antrum pyloricum, which is the narrowed part; canalis pyloricus is located in the sphincter area. Knowledge of these parts is important for describing the localization of many pathological changes in gastric diseases. The pylorus of the stomach (pylorus) leads into the opening (ostium pyloricum), which opens into the cavity of the duodenum.

All parts of the stomach have anterior and posterior walls (paries ventriculi anterior et posterior), which are connected into the lesser curvature of the stomach (curvatura ventriculi minor), concavely facing to the right, and the greater curvature (curvatura ventriculi major), convexly facing to the left.

Stomach shape. In a corpse, the stomach has the shape of a retort, which is caused by the loss of tone of the muscular layer and the muscular layer of the mucous membrane. Under pressure from gases, the stomach stretches and enlarges. In a living person, an empty stomach resembles an intestine and only expands when filled with food. The shape of the stomach largely depends on the human constitution.

Horn shaped stomach. It occurs more often in people of brachymorphic build. It is located with a long axis from left to right (Fig. 231).

Fishhook shaped stomach. The body of the stomach descends. At the junction of the body and the pyloric part there is an angle (Fig. 232). The pyloric sphincter is located slightly above the lower pole of the stomach. A stomach of a similar shape is found in normosthenics - people of average height and build.

Stocking shaped stomach. To some extent, it resembles a fishhook-shaped stomach. A distinctive feature is that the lower pole of the stomach is located significantly lower than the sphincter of the pyloric part (Fig. 233). In this regard, the pyloric part of the stomach has an ascending direction. This form is more common in people with dolichomorphic build.

Topography of the stomach. The stomach is located in the abdominal cavity in the regio epigastrica. The longitudinal axis of the stomach is projected to the left of the spine. The place where the esophagus enters the stomach on the left side corresponds to the body of the XI thoracic vertebra, and the pyloric sphincter is located to the right of the XII thoracic, sometimes I lumbar vertebra. The vault of the stomach is in contact with the left dome of the diaphragm. In this case, the upper border corresponds to the fifth left rib along the midclavicular line. An empty stomach does not go below the linea biiliaca (the line between the crests of the iliac bones). The anterior wall of the stomach in the cardiac and pyloric parts along the lesser curvature is covered with the liver. The anterior wall of the body of the stomach is in contact with the parietal peritoneum of the anterior abdominal wall (Fig. 234). The posterior wall in the area of the arch and greater curvature is in contact with the spleen, adrenal gland, upper pole of the kidney and pancreas, and in the area of the lower 2/3 of the greater curvature - with the transverse colon.

Stomach wall. It consists of a mucous membrane (tunica mucosa) with a submucosal layer (tela submucosa), a muscular layer (tunica muscularis) and a serous membrane (tunica serosa).

The mucous membrane is covered with single-layer prismatic epithelium (intestinal type), which has the property of secreting mucoid secretion (mucus) with its apical end (facing the stomach cavity). Mucus protects the stomach wall from the action of pepsin and hydrochloric acid, preventing self-digestion of the mucous membrane. In addition, mucus serves as a protective layer for the mucous membrane when exposed to rough food. The gastric epithelium is located on the connective tissue lamina propria of the mucous membrane, consisting of elastic fibers, loose connective tissue and formed elements (fibroblasts, lymphocytes, leukocytes). In the submucosal layer there are nodules of lymphatic tissue (folliculi lymphatici gastrici). At the border with it there is a muscle layer (lamina muscularis mucosae). The contraction of these muscles causes the formation of folds (plicae gastricae) in the mucous membrane (Fig. 235). These folds in the area of the arch and the greater curvature are located without a specific order, and along the lesser curvature they are oriented longitudinally. They are clearly visible when x-raying an empty stomach. On the mucous membrane, in addition to folds, there are fields and pits. The gastric areas (areae gastricae) are outlined by small grooves that divide the surface of the mucous membrane into areas where the mouths of the digestive glands are located (Fig. 236). Gastric pits (foveolae gastricae) are retractions of the epithelium into the own layer of the mucous membrane. At the bottom of the pits, the ducts of the digestive glands open.

236. The surface of the gastric mucosa, photographed in incident light. ×200

Glands. There are three types of glands: cardiac (gll. cardiacae), fundic (gll. gastricae) and pyloric (gll. pyloricae). Cardiac glands are simple tubular. Their secretory sections are localized in their own layer of the mucous membrane. They produce a mucus-like secretion mixed with the enzyme dipeptidase, which can break down proteins into amino acids, a glycolytic enzyme for the breakdown of carbohydrates, and also a secretion of an alkaline reaction. All glands of the stomach can be excited by the action of nutrients or nerve impulses of the autonomic nervous system.

The fundic glands are in the form of branched tubes that open into the gastric pits, lined with gastric epithelium. The glands are formed by chief, parietal and accessory cells. The chief and parietal cells secrete gastric juice containing hydrochloric acid. Accessory cells are located near the isthmus of the glands and secrete mucus of an alkaline reaction, reminiscent of the mucus secreted by the prismatic epithelium of the gastric mucosa.

The pyloric glands are more branched than the cardiac and fundic glands. The pyloric glands are formed by various cells that produce pepsin and mucous secretions.

The submucosal layer of the stomach is well developed, consisting of loose connective tissue with dense vascular and nerve plexuses. The muscular layer is conventionally divided into three layers: the outer longitudinal (stratum longitudinale), the middle circular (stratum circulare) and the inner (stratum internum), consisting of oblique fibers (librae obliquae) (Fig. 237). The circular and longitudinal layers are best developed in the pyloric part, worse in the fornix and upper part of the body of the stomach. The longitudinal layer is clearly visible on the lesser and greater curvature of the stomach. It starts from the esophagus and ends at the pyloric part. When the longitudinal layer contracts, the stomach shortens and the shape of the greater and lesser curvature changes. The inner muscular layer from the cardiac part passes along the lesser curvature, giving portions to the body of the anterior and posterior walls, the greater curvature of the stomach. When it contracts, the notch of the cardiac part increases, and the greater curvature is tightened. Circular muscle fibers surround the stomach, starting from the esophageal opening and ending with the pyloric sphincter, which is also a derivative of this muscle layer. The pyloric sphincter (m. sphincter pylori) has the shape of a ring 4-5 mm thick.

The mucous membrane, due to the contraction of the lamina muscularis mucosae, tightly covers the food bolus. The muscular lining of the stomach wall also has its own tone. In the stomach, the pressure rises to 40 mm, and in the pyloric part - up to 150 mm Hg. Art. It is necessary to distinguish between tonic and periodic types of contraction of the stomach muscle. With tonic contraction, it is constantly contracted and the wall of the stomach actively adapts to the food bolus. Periodic contractions occur approximately every 18-22 s. in the vault area and gradually spread towards the pyloric sphincter. The food gruel is in close contact with the wall of the stomach. Periodic waves of the circular layer remove a layer of digested gruel from the surface of the food bolus and collect it in the pyloric part. The pyloric sphincter is almost always closed. It opens when alkalization of the contents occurs in the pyloric part. In this case, a portion of semi-liquid gruel is released into the duodenum. As soon as the acidic portion of food reaches the initial part of the duodenum, the sphincter closes until the gastric juice is neutralized. Solid food stays in the stomach for a long time, while liquid food enters the intestines faster.

The serous membrane covers the stomach on all sides, i.e. intraperitoneally. The peritoneum externally contains mesothelium, located on a connective tissue base having six layers.

Gastric ligaments. The ligaments of the stomach and other organs of the digestive system are not the same ligaments that are found in the musculoskeletal system, but are thickened layers of the peritoneum.

The diaphragmatic-esophageal ligament (lig. phrenicoesophageum) is a piece of peritoneum that passes from the diaphragm to the esophagus and the cardial notch of the stomach. The esophageal arterial branch from the left gastric artery passes through the thickness of the ligament.

The diaphragmatic-gastric ligament (lig. phrenicogastricum), like the previous one, is a piece of the diaphragmatic peritoneum, which, descending from the diaphragm, is attached to the vault of the stomach.

Gastrosplenic ligament (lig. gastrolienale): it consists of two layers of peritoneum, passing from the anterior and posterior walls in the upper part of the greater curvature of the stomach to the visceral surface of the spleen. In the thickness of the ligament, vessels pass to the bottom of the stomach.

The gastrocolic ligament (lig. gastrocolicum) connects 2/3 of the greater curvature of the stomach with the transverse colon. It represents the leaves of the upper part of the greater omentum fused together. The right and left gastroepiploic arteries and vein of the stomach pass through the ligament.

The hepatogastric ligament (lig. hepatogastricum) is a two-layer sheet stretched between the hilum of the liver and the lesser curvature of the stomach. The ligament is a transformed ventral mesentery that existed in the embryonic period of development. In the upper part the ligament is thin and transparent, and closer to the pyloric sphincter it is thicker and more tense.

The gastropancreatic ligament (lig. gastropancreaticum) and the pyloric-pancreatic ligament (lig. pyloropancreaticum), formed by one layer of the peritoneum, are visible when dissecting the lig. gastrocolicum. This releases the greater curvature of the stomach, which can be raised and then penetrated into the omental bursa (bursa omentalis).

In a newborn, the long stomach is oriented vertically. The arch and body are expanded, and the pyloric part is narrowed. The pyloric part is relatively longer in relation to other parts of the stomach. The volume of a newborn's stomach is 30 ml; under the influence of food it increases over the course of a year to 300 ml. By puberty, the volume of the stomach reaches 1700 ml. Babies have more cells that produce lipase and lactase, which help break down the nutrients in milk.

X-rays of the stomach

X-ray examination of the stomach is a common procedure in clinics and clinics. Most often, contrast is carried out with barium mass, air in combination with parietography (injection of gas into the peritoneal cavity) in the form of overview and targeted images.

The overview image reveals the general contours and shape of the stomach. It shows the fornix containing a gas bubble, the cardiac part, the body, and the pyloric part. The contours of the stomach, which reflect the internal relief, are of great importance. During peristalsis of the stomach, circular retractions are formed on the greater and lesser curvature due to muscle contraction. In case of changes in the cardiac part and the vault of the stomach, it is necessary to determine the relationship to the diaphragm, the width and depth of the angle between the esophagus and the vault of the stomach. It is very important to trace the medial contour of the gastric vault and the wall of the esophagus facing it, and then the cardiac part. Normally, these sections have a smooth surface.

The sphincter canal has a length of 1 cm, a diameter of 2-3 mm and opens in the central part of the duodenal bulb.

When the stomach is slightly filled, especially with a liquid suspension of barium mass, it is distributed mainly between the folds; in the body of the stomach there are 4-5 folds 3-5 mm wide. In the area of the fornix and pyloric part they have an oblique position. A targeted image reveals any detail of the structure of the stomach, for example, the state of the folds of its body. These images are very valuable for x-ray diagnostics.

Parietograms can only be performed by contrasting the abdominal cavity and stomach with air. This method is very effective; it helps to identify the external and internal relief of the stomach wall. Pictures are taken in anterior projection.

The stomach is a hollow, expanded section of the digestive tract, a temporary reservoir of food located in the epigastrium - the upper part of the abdominal cavity. The stomach continues the esophagus and is shaped like a bag.

In the stomach there are:
The cardia is the entrance part of the stomach, next to the esophagus, after which there is a sphincter. The cardiac section is located closer to the heart, which is why it has this name. Translated from Latin, “-kor” means heart;
Home ( main) part - represented by the bottom and body, which do not have clear boundaries, and their configuration changes as the stomach fills or empties;
Pyloric ( antral) department - includes the pyloric canal and the pylorus, inside which there is a circular pyloric sphincter that separates the stomach from the duodenum.

In addition, in the stomach there are: anterior and posterior walls, a greater curvature facing the spleen and a lesser curvature facing the liver.

The walls of the stomach are represented by four membranes:
The internal mucous membrane forms many folds, which smooth out when the stomach is filled with food, and if the stomach is empty, they protrude sharply. The mucous membrane is divided into pyloric, fundic and cardiac zones. They correspond to the anatomical divisions of the stomach and do not have clear boundaries. Certain areas of the stomach have deeply buried glands. They distinguish three types of cells: parietal ( lining) cells – form hydrochloric acid; chief cells - produce pepsin; mucus-forming ( mucoid) cells - form mucus, which protects the gastric mucosa from the aggressive effects of hydrochloric acid;
The submucosa consists of vessels, connective tissue and the nerve plexus, which is a collection of nerve cells and bundles;
The muscular layer is represented by internal circular and external longitudinal layers of muscles;
The serous membrane covers the outside of the stomach and prevents it from adhering to surrounding organs.

Stomach functions

Secretory-digestive function consists in the secretion of gastric juice, which consists of: hydrochloric acid; pepsin, which digests protein into peptides; chymosin ( rennet), which breaks down casein and curdles milk; mucus that protects the walls of the stomach from aggressive hydrochloric acid; lipase, neutral chloride and hematopoietic enzyme;
Motor function lies in the ability of the walls of the stomach to perform peristaltic movements, which are more pronounced in the pyloric part during the transition of the chyme ( split food) into the duodenum. In various pathologies, for example, poisoning, the walls of the stomach perform antiperistaltic movements, accompanied by emptying of the stomach and the release of vomit. The abdominal muscles and diaphragm take part in antiperistalsis;
Tone function– the ability of the stomach to adapt to any volume created by food that fills it;
Excretory function carried out more by the gatekeeper part. Through the mucous membrane of the stomach with the blood flow, some substances are able to penetrate into its cavity: lactic acid, some poisons, alcohol, morphine, etc. Absorption in the stomach is poor. Of all the known substances, alcohol and carbon dioxide are absorbed best and fastest.

A “hungry” stomach does not secrete secretions and undergoes strong contractions with a characteristic rumbling sound. From the moment of swallowing, the rumbling stops. The food eaten is placed in layers from the walls of the stomach to the middle. The layer of food located outside is digested faster and moves first to the duodenum, where its digestion continues under the influence of bile and pancreatic juice.

The formation of the stomach begins from the intestinal tube from the 4th week of intrauterine development. Starting from the 16th week of embryonic development, gastric glands are formed.

Stomach diseases

Gastritis– inflammation of the gastric mucosa. Acute gastritis occurs, for example, when taking high doses of aspirin after irradiation. Symptoms of gastritis: burning and pain in the epigastric region, which subside slightly after eating food; nausea and vomiting; a feeling of bloating in the upper abdomen, etc. Chronic gastritis, as well as peptic ulcer disease, occurs as a result of the activity of the bacterium Helicobacter pylori. The pathogen very often provokes gastritis with hypersecretion of gastric juice;
Ulcer– a chronic disease of the gastric mucosa with the formation of a defect in its wall. Very often, an ulcer occurs against the background of gastritis. Men aged 40 years are more often affected. In addition to Helicobacter pylori, disease factors include: stress, poor diet, genetic predisposition, smoking, etc. Ulcer symptoms: hunger pains that go away half an hour after eating, heaviness, cramps, heartburn, and sometimes vomiting. On the Internet you can find many photos depicting an ulcerative defect of the stomach wall. Ulcer complications: perforation ( formation of a hole in the wall of the stomach with heavy bleeding), malignancy – degeneration of an ulcer into a malignant tumor, etc.;
Stomach cancer– a malignant tumor that develops from the gastric mucosa. The causes of cancer include: infectious factors, carcinogens, heredity, alcohol and smoking. In the early stages, the stomach affected by the tumor practically does not hurt. As the tumor grows, symptoms increase: pain, indigestion, frustration, vomiting, belching, aversion to meat foods;
Polyps– benign, tumor-like formations arising from the gastric mucosa in the form of outgrowths. Helicobacter pylori polyps, chronic stomach diseases, and heredity contribute to the appearance of polyps. Small polyps subjectively do not cause any problems or complaints in the patient. Large polyps can cause difficulty in the passage of food in the stomach, bleeding and severe pain when pinched.

Diagnostics

In addition to examining and interviewing the patient, instrumental research methods are of great value in making a diagnosis, which help to recognize the disease in the early stages and plan treatment.
Gastroscopy or FGS is a method by which the doctor can directly examine the gastric mucosa and determine inflammation, ulcerative defect, scarring, the presence of a tumor, for example, a polyp, etc.;
Ultrasound - is used very rarely, since the stomach is a hollow organ and is practically not visualized by an ultrasound wave;
X-ray is a widely used method for determining volumetric pathologies, niches, as well as the location of the stomach. With its help, prolapse, tumors, ulcers, etc. are detected;

Treatment

A gastroenterologist treats stomach diseases. In modern gastroenterology, medicinal methods are most widespread in the treatment of gastritis, peptic ulcers, poisoning, etc. Of all the drugs, adsorbents, antiemetics, antacids, appetite regulators, etc. are most often used, usually in the form of tablets. As an auxiliary therapy, your doctor may prescribe folk remedies in the form of decoctions, infusions and herbal tinctures.

If conservative methods are ineffective, stomach diseases are treated with surgery. For example, complicated peptic ulcer with heavy bleeding. Some gastric surgeries are performed under local anesthesia, such as removal of a small polyp during gastroscopy of the stomach.

Some patients undergo surgery to reduce the size of the stomach in order to lose excess weight. Patients undergo gastric bypass or gastric banding. During bypass surgery, a resection (crossing) of the upper part of the stomach is performed and a small “new” organ is formed. Due to its reduced size, the stomach holds little food and, therefore, a person loses weight over time. The price of bypass surgery in many clinics starts from 7,000 rubles. Losing weight is possible after undergoing a similar gastric band procedure. Only instead of resection, a special ring is applied to the upper part of the stomach - a bandage, which also divides the stomach into two halves and artificially reduces its volume. Thus, assistance is provided to patients with obesity.

Prevention of stomach diseases consists of following a healthy lifestyle and the principles of proper nutrition.