afo of the gastrointestinal tract in children

The laying of the organization of digestion occurs at an early stage of embryonic development. Already by the 7-8th day from the endoderm → the primary intestine, from which 2 parts are formed on the 12th day: intraembryonic(future digestive tract), extraembryonic(yolk sac).

From the 4th week of embryogenesis, the formation of various departments begins:

from the foregut the pharynx, esophagus, stomach and part of the duodenum with the rudiments of the pancreas and liver develop;

from the midgut a part of the duodenum, jejunum and ileum is formed;

from the back- all parts of the colon develop.

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Oral cavity has features that provide the act of sucking:

relatively small volume of the oral cavity;

big tongue;

good development of the muscles of the mouth and cheeks;

roller-like duplicatures of the mucous membrane of the gums;

fat bodies (Besh lumps);

The salivary glands are underdeveloped.

Esophagus formed at birth. The entrance to the esophagus in a newborn is at the level between the III and IV cervical vertebrae, at the age of 12 - at the level of the VI-VII vertebrae. Funnel-shaped. The length of the esophagus increases with age. Anatomical narrowings are weakly expressed.

The transition of the esophagus to the stomach in all periods of childhood at the level of the X-XI thoracic vertebrae.

Stomach in children infancy located horizontally. As the child begins to walk, the axis of the stomach becomes vertical.

in newborns, poor development of the fundus and cardiac region

the cardiac sphincter is very poorly developed, and the pyloric one functions satisfactorily  tendency to regurgitation;

there are few glands in the mucosa  the secretory apparatus is underdeveloped and its functional abilities are low;

the composition of gastric juice is the same, but the acid and enzymatic activity is lower;

the main enzyme of gastric juice is chymosin (rennet), which provides curdling of milk;

there is little lipase and its low activity;

the timing of the evacuation of food from the stomach depends on the type of feeding;

motility of the gastrointestinal tract is slowed down, peristalsis is sluggish;

the physiological volume is less than the anatomical capacity and at birth is 7 ml. On the 4th day - 40-50 ml, by the 10th day - up to 80 ml. By the end of 1 year - 250 ml, by 3 years - 400-600 ml. At the age of 4-7 years, the capacity of the stomach increases slowly, by the age of 10-12 it is 1300-1500 ml.

With the onset of enteral nutrition, the number of gastric glands begins to increase rapidly. If a fetus has 150-200 thousand glands per 1 kg of body weight, a 15-year-old has 18 million.

Pancreas pancreas is not completely formed by birth;

at birth, weight  3 g, in an adult 30 times more. Iron grows most intensively in the first 3 years and in the pubertal period.

at an early age, the surface of the gland is smooth, and by the age of 10-12, tuberosity appears, which is due to the isolation of the boundaries of the lobules. In newborns, the head of the pancreas is most developed;

trypsin, chymotrypsin begins to be secreted in utero; from 12 weeks - lipase, phospholipase A; amylase only after birth;

secretive activity of the gland reaches the level of adult secretion by the age of 5;

Liver parenchyma is little differentiated;

dollatity is detected only by 1 year;

by the age of 8, the morphological and histological structure of the liver is the same as in adults;

the enzymatic system is untenable;

by birth, the liver is one of the largest organs (1/3 - 1/2 of the volume abdominal cavity, and mass = 4.38% of the total mass); the left lobe is very massive, which is explained by the peculiarities of the blood supply;

the fibrous capsule is thin, there are delicate collagen and elastic fibers;

in children 5-7 years old, the lower edge extends from under the edge of the right costal arch by 2-3 cm;

in the composition of the liver, the newborn has more water, at the same time less protein, fat, glycogen;

there are age-related changes in the microstructure of liver cells:

in children, 1.5% of hepatocytes have 2 nuclei (in adults - 8.3%);

the granular reticulum of the hepatocyte is less developed;

many free-lying ribosomes in the endoplasmic reticulum of the hepatocyte;

glycogen is found in the hepatocyte, the amount of which increases with age.

gallbladder in a newborn, it is hidden by the liver, has a spindle shape  3 cm. Bile differs in composition: poor in cholesterol; bile acids, the content of bile acids in hepatic bile in children aged 4-10 years is less than in children of the first year of life. At the age of 20, their content again reaches the previous level; salts; rich in water, mucin, pigments. With age, the ratio of glycocholic and taurocholic acids changes: an increase in the concentration of taurocholic acid increases the bactericidal activity of bile. Bile acids in the hepatocyte are synthesized from cholesterol.

Intestines relatively longer in relation to body length (newborn 8.3:1; adult 5.4:1). In children early age besides, the intestinal loops lie more compactly, because the pelvis is not developed.

in young children, there is a relative weakness of the ileocecal valve, and therefore the contents of the caecum, the richest in bacterial flora, can be thrown into the ileum;

due to weak fixation of the rectal mucosa in children, its prolapse can often occur;

mesentery longer and more easily distensible easy = torsion, intussusception;

omentum short  diffuse peritonitis;

structural features of the intestinal wall and its large area determine a higher absorption capacity and, at the same time, an insufficient barrier function due to the high permeability of the mucosa for toxins and microbes;

In children of all ages, the maltase activity of the small intestine mucosa is high, while its sucrase activity is much lower. The lactase activity of the mucosa, noted in the first year of life, gradually decreases with age, remaining at a minimum level in an adult. Disaccharidase activity in older children is most pronounced in the proximal small intestine, where monosaccharides are mainly absorbed.

In children older than 1 year, as in adults, protein hydrolysis products are absorbed mainly in the jejunum. Fats begin to be absorbed in the proximal ileum.

Vitamins and minerals are absorbed in the small intestine. Its proximal sections are the main site of nutrient absorption. The ileum is the reserve zone of absorption.

The length of the large intestine in children of different ages is equal to the length of the body of the child. By the age of 3-4, the structure of the sections of the large intestine of a child becomes similar to the anatomy of the corresponding sections of the adult intestine.

Juice secretion by the glands of the large intestine in children is weakly expressed, but it increases sharply with mechanical irritation of the mucosa.

motor activity is very energetic (increase in the act of defecation).

By birth all enzymes membrane digestion, have high activity, the topography of enzymatic activity throughout the small intestine or distal shift, which reduces the reserve capacity of membrane digestion. In the same time intracellular digestion, carried out by pinocytosis in children of the 1st year of life, is much better expressed.

Transient dysbacteriosis passes on its own from the 4th day

in 60-70% - pathogenetic staphylococcus aureus

30-50% - enterobacterial, Candida

10-15% - proteus

Excreta:

Meconium (intestinal contents, I. Aseptic phase (sterile).

accumulated before childbirth and up to II. The phase of colonization by flora (dysbacteria-

first application to the breast; oz coincides with toxic erytherma).

consists of intestinal III cells. The phase of displacement of the bifidobacter flora

epithelium, amniotic fluid). terium.

Transitional stool (after 3rd day)

Newborn stool (from the 5th day

birth).

Features of digestion in children

By birth, the salivary glands are formed, but the secretory function is low for 2-3 months. -amylase of saliva is low. By 4-5 months there is profuse salivation.

By the end of the 1st year, hydrochloric acid appears in the gastric juice. Among the proteolytic enzymes, the action of renin (chymosin) and gastrixin predominates. Relatively high activity of gastric lipase.

At birth, the endocrine function of the pancreas is immature. Pancreatic secretion increases rapidly after the introduction of complementary foods (with artificial feeding functional maturation of the gland is ahead of that in the natural). Particularly low amylolytic activity.

Liver relatively large at birth, but functionally immature. The excretion of bile acids is small, at the same time, the liver of a child of the first months of life has a greater “glycogenic capacity”.

Intestines in newborns, as it were, it compensates for the insufficiency of those organs that provide distant digestion. Of particular importance is membrane digestion, whose enzymes are highly active, the topography of enzymatic activity throughout the small intestine in newborns has a distal shift, which reduces the reserve capacity of membrane digestion. In the same time intracellular digestion, carried out by pinocytosis, in children of the 1st year is expressed much better than at an older age.

During the 1st year of life there is a rapid development distant digestion which is increasing in importance every year.

Disaccharides (sucrose, maltose, isomaltose) are subjected, like lactose, to hydrolysis in the small intestine by the corresponding disaccharidases.

Digestive system- the organ system in which the digestion of food occurs, the absorption of processed and the release of undigested substances. It includes the digestive tract and digestive glands.

digestive tract- this is the tubular part of the digestive system, it distinguishes the oral cavity, pharynx, esophagus, stomach, small and large intestine (Fig. 8.4). In turn, the stomach, small and large intestines make up the gastrointestinal tract.

digestive glands(salivary, gastric, intestinal, pancreas, liver) are located along the digestive tract and produce digestive juices.

The breakdown of food nutrients occurs under the influence of three types of enzymes:

■ proteolytic - break down proteins to polypeptides and amino acids;

■ amylolytic - carbohydrates to disaccharides and monosaccharides;

"lipolytic - fats to fatty acids and glycerol.

Digestion and absorption are the main components of a functional digestive system that maintain a constant level of nutrients in the body.

The main function of the digestive system is to maintain a level of nutrients in the body that ensures the normal course of metabolic processes. Reducing the content of nutrients in the body through the excitation of chemoreceptors of the gastrointestinal tract, blood vessels

Rectum

Rice. 8.4. Digestive organs

and tissues in a nervous and humoral way excites parts of the food center located in the hypothalamic region. This excitement causes:

■ release of reserve nutrients;

■ redistribution of reserve nutrients to more important organs;

■ reducing the consumption of nutrients and metabolic processes in the cells and tissues of the body.

From the moment you eat until the nutrients enter your bloodstream, it takes time for digestion and absorption. However, the restoration of the normal level of nutrients in the blood begins already at the moment food enters the oral cavity and stomach due to the transmission of impulses from the receptors of the oral cavity and stomach to the hypothalamus. After the intake of nutrients

Substances in the blood is metabolic saturation, which restores the original level of nutrients in the body.

Functionally, the digestive system is morphologically formed by the time of birth, but is still immature. The maturation of this system occurs intensively in the first five years, especially in 1-3 years, when the child switches from milk nutrition to artificial and mixed. In the future, not only separate links of the nutrition and absorption system develop, but also food-procuring activities. The maturation of the digestive system is completed by the age of 12.

8.3.1. Morphofunctional transformations in the oral cavity

The oral cavity of the newborn baby relatively small, the alveolar processes and the arch of the hard palate are weakly expressed. A relatively large tongue almost completely fills a small oral cavity. In the thickness of the cheeks of the newborn there are dense fat pads. A dense roller stretches along the jaw processes - a duplication * of the mucous membrane. The visible part of the lip mucosa in a newborn has transverse folding. All of the listed anatomical features allow the newborn to most grasp the nipple of the mother's breast during the act of sucking.

The mucous membrane of the oral cavity is distinguished by its bright color, tenderness, an abundance of blood vessels and some dryness. Dryness of the oral cavity is due to the fact that in children from the moment of birth, the salivary glands, although they function, but the secretion of saliva is insignificant, since:

■ the oral mucosa is poor in salivary glands;

■ paired salivary glands are quite small; "underdeveloped central nervous system;

■ nutrition of a newborn baby - basically breast milk, that's why
saliva plays a minor role in digestion.

In children saliva secretion begins immediately after birth, but in the first months of saliva is separated little. With the appearance of milk teeth, salivation intensifies. In the oral cavity of children, as well as adults, the ducts of three pairs of large salivary glands open: parotid, submandibular and sublingual. In addition to large salivary glands, there are small mucous membranes, they are scattered over almost the entire mucous membrane of the oral cavity and tongue. With age, the glands increase in size, the glandular tissue itself grows, and the glandular ducts expand and branch. By the age of 2, the salivary glands are similar in structure to the structure of adults.

* Duplication - an anatomical formation, consisting of two layers of any lamellar structure.

From 4-6 months of age, salivation in infants increases significantly. Children do not have time to swallow saliva in a timely manner, and it flows out of the mouth (physiological salivation). Increased salivation is associated with: I ■ irritation of the trigeminal nerve, erupting teeth;

■ an increase in the relative mass of the salivary glands;

■ introducing complementary foods into the baby's food.

In total, about 800 ml of saliva is secreted in children per day.

The saliva of children is a mixture of the secretions of the salivary glands, has neut
ral reaction, less often - slightly acidic and slightly alkaline, pH 6.0-7.8. In the saliva
an enzyme is detected alpha amylase, which breaks down starch. At the newborn
This enzyme has little activity over the next month!
its activity increases rapidly, reaching a maximum by 2-7 years of age. In chest
At a certain age, a second enzyme appears in saliva - maltase which also
produced by the pancreas, promotes the breakdown of maltose
into glucose during digestion. -h

The greatest enzymatic activity of saliva is a period from 1 to 4 years. Along with enzymes, the saliva of children contains lysozyme, bactericidal, mucous substance mucin, some nitrogenous substances and a number of mineral salts: phosphates, bicarbonates, sodium, potassium, calcium.

The regulation of salivary secretion in children is carried out in a complex reflex way, and unconditioned salivary secretion after eating decreases, as the excitability of the food center decreases. The degree of decrease in excitability depends on the nature of the nutrients. In newborns, there is no conditioned reflex component in the regulation of secretion.

Swallowing and sucking reflexes appear in the fetus at the 5th month of development. The baby is born with a well-defined sucking reflex. The suckling center is located in the medulla oblongata.

Reflex arc of the sucking reflex:

■ receptors of the oral mucosa;

■ centripetal fibers are part of the trigeminal nerve;

■ centrifugal fibers are part of the trigeminal, facial and hypoglossal nerves;

■ working organ - chewing muscles, muscles of the lips and mouth, muscles of the tongue.

The act of sucking is an innate unconditioned reflex act. The act of sucking is influenced by a complex of irritations from the receptors of the lips and oral cavity, which are the afferent part of the unconditioned food reflex. The act of sucking during the first days of life becomes more perfect and automated due to the system of reverse afferentation, which evaluates the usefulness of the performed action, the processes of self-regulation and adaptive activity.

13 Age anatomy

The swallowing reflex is even more constant than the sucking reflex. Only the strength. but premature babies or with very gross defects in the development of the central nervous system, this ref. medicine may be missing.

8.3.2. Morphofunctional transformations of the esophagus and stomach

Esophagus- muscular tube with a diameter of about 2.2 cm and a length of 23-28 cm, comp. aching throat with stomach. The esophagus is divided into cervical, thoracic and abdominal parts. The esophagus has several physiological constrictions. In the lower part there is a sphincter, the contraction of which closes the entrance to the stomach. When swallowing, the sphincter relaxes and the food bolus enters the stomach.

The esophagus performs only a transport function (by successive contractions of the annular muscles from top to bottom). The speed of movement of food to the stomach is 1-9 seconds, depending on the consistency.

The esophagus in young children has a funnel-shaped form. The mucous membrane of the esophagus is tender, easily injured, rich in blood and lymphatic vessels. The muscular layer, elastic tissue and mucous glands are underdeveloped. In a newborn, the length of the esophagus is on average 13.9 cm, in children at 6 months - 16.6 cm; at 1 year - 17.6 cm; at 3 years - 20.5 cm. By the age of two, sex differences appear in the length of the esophagus: in girls it is shorter.

The diameter of the esophagus in 2-month-old children is 7-8 mm, at 6 months - 9 mm. By the end of the first year and up to two years - 10 mm, at the age of 6 to 12 years - 12-15 mm.

Up to two years, the upper border of the esophagus with a straight head position is located at the level of 4 and 5 cervical vertebrae, by 12 years - at the level of 5 and 6. The lower border of the esophagus is located at the level of the middle of the 10th thoracic vertebra and its location does not change with age.

Stomach- this is an expanded section of the digestive canal, located in the upper part of the abdominal cavity under the diaphragm, between the end of the esophagus and the beginning of the duodenum. It is the mechanical and chemical processing of food under the action of gastric juice.

In the stomach, the anterior and posterior walls are distinguished, concave (small curvature) and convex (large curvature) the edges. The part of the stomach adjacent to the entry point of the esophagus into the stomach is called cardiac, dome-shaped protrusion of the stomach - bottom, or fundus, middle part - stomach body, and the area that passes into the duodenum - gatekeeper, or pyloric, part of the stomach.

In infants, the stomach is located horizontally, when the child begins to stand and walk, he assumes a vertical position. Proportions characteristic of adults between different parts of the stomach are established in children by the age of 10-12. The capacity of the stomach in a newborn is 30-33 ml. In the future, it increases by approximately 20-25 ml per month, reaching 100 ml by three months, and 250 ml by a year.

The mucous membrane of the stomach during early childhood is quite thick. It has a lot of blood vessels, little elastic tissue, poorly developed muscle with doJ and few lymph nodes. The sphincter of the entrance to the stomach is very weakly expressed, and the pyloric muscle layer is strong enough, so the child is prone to regurgitation and vomiting.

The mucous membrane of the stomach has a large number of folds, in the pits of which
are the glands that secrete gastric juice. There are gastric
natural) glands located in the region of the bottom and body T "and the glands of the pylorus (pi-
loric). The gastric glands are numerous and contain three types of cells:
"■ main - producing enzymes; ;:""

■ lining - emitting hydrochloric acid; ft "additional - secreting mucus."

The pyloric glands do not contain cells that produce hydrochloric acid.

The secretory function of the cells is reduced. The acidity and enzymatic power of the gastric juice increase significantly towards the end of the cervic year.

Gastric juice- colorless transparent liquid - acid reaction (pH 1.0-. 1.5). For a day, an adult produces 2.0-2.5 gastric juice. Thanks a large number juice, the food mass turns into a liquid slurry - chyme.

The composition of gastric juice includes water (99%) and dense substances (1%). Dense substances include organic (enzymes, mucus, lysozyme) and inorganic (hydrochloric acid) components.

Gastric juice enzymes are proteases And lipase. The main proteolytic enzymes include pepsins A, B (parapepsin), C (gastrixin). Pepsin A and gastrixin, acting together on different types proteins, provide 95% of the proteolytic activity of gastric juice. Pepsin A hydrolyses proteins at a maximum rate at pH 1.5-2.0, gastrixin at pH 3.2-3.5.

The gastric contents in infants, even at the height of digestion, almost never reach high acidity, however, under the action of pepsin, a significant part of milk proteins is broken down. The amount of pepsin in children depends on age, health status, constitutional features, method of feeding, etc. Pepsin in children has low activity.

The gastric juice of children contains the enzyme cathepsin (primary protease), the optimal action of which is at a pH of about 5-6.

Thus, when feeding a child up to 8 months, the amount of protein food (except milk) should be limited.

Chymosin- rennet, causes curdling of milk in the presence of calcium ions, i.e., it converts the soluble caseinogen protein into insoluble casein. Children's gastric chymosin acts at pH 6.0. It can act not only in slightly acidic, but also neutral and even slightly alkaline reactions, which is important for the digestion of milk proteins in young children, in which the acidity in the stomach is negligible.

Lipase(lipolytic enzyme) digests emulsified fats Especially easy to hydrolyze milk fats. Enzyme activity increases with age. Lipolysis in children on breastfeeding, occurs much more vigorously than in children on artificial nutrition, since in the first, the breakdown of fats in the stomach occurs not only due to the lipase of gastric juice, but also due to the lipase of human milk.

The process of separation of gastric juice occurs in two phases. The first is the cerebral, or complex reflex, phase of secretion - a complex of conditioned and unconditioned reflexes resulting from the action of conditioned stimuli (smell, type of food, sound stimuli associated with cooking, environment, talking about food, etc.) on the receptors of organs feelings and unconditioned stimulus (food) on the receptors of the oral cavity, pharynx and esophagus. The juice released in the first phase is especially valuable, as it is rich in enzymes. I. P. Pavlov called this juice “ignition”. The separation of the "ignition" juice causes appetite and creates normal conditions for digestion in the stomach and small intestine. Beautifully presented food, appropriate serving and aesthetic environment stimulate the release of the ignition juice and improve digestion.

The second - the neurohumoral phase of secretion - consists of a complex of unconditioned reflexes that occur during the passage of food through the gastrointestinal tract, and the humoral influence of hormones resulting from the hydrolysis of nutrients. The second phase is divided into gastric and intestinal.

The gastric phase begins from the moment food enters the stomach as a result of direct irritation of the receptors of the gastric mucosa by food. The intestinal phase begins with the transition of chyme from the stomach to the intestines as a result of exposure to intestinal receptors, which reflexively changes the intensity of secretion.

The motor function of the stomach in young children is somewhat slow, peristalsis is sluggish. Food is in the stomach of children with natural feeding for approximately two to three hours, and with artificial feeding - three to four hours.

8.3.3. Morphofunctional transformations of the intestine

Duodenum - the central link of the digestive conveyor, which is the initial section of the small intestine, has the shape of a horseshoe 25-27 cm long in an adult.

The food coming from the stomach in the duodenum is exposed to pancreatic juice, bile and intestinal juice, as a result of which the end products of digestion are easily absorbed into the blood. Pancreatic juice is produced by the pancreas, bile - by the liver, intestinal juice - by many small glands present in the mucous membrane of the intestinal wall.

The duodenum in newborns is located at the level of the first lumbar vertebra, has the shape of a ring. By 6 months, she has determined

descending and ascending sections, the upper part of the intestine is at the level of the twelfth thoracic vertebra, in children of 7 years old - slightly lower, in children of 12 years old - at the level of the twelfth and first lumbar. The duodenum in children is mobile.

Digestion in the duodenum in children, as in adults, takes place under the influence of pancreatic juice, intestinal juice and bile. The contents of the stomach in the form of a food slurry soaked in acidic gastric juice passes in portions from the stomach into the duodenum, where the common bile duct and the pancreatic duct open. A mixture of secrets of the pancreas, duodenum and liver form duodenal juice. The activity of duodenal juice enzymes increases with age.

Pancreas is the main site for the production of digestive enzymes. The cellular development of the pancreas ends already in the first months of a person's life, and its growth continues up to 11 years.

The composition of pancreatic juice includes; enzymes (trypsinogen, amylase, maltase, lipase) and inorganic substances ^-c "olis of sodium, potassium, calcium, iron, etc., creating an alkaline juice reaction.

The mechanism of regulation of juice secretion is the same as in adults: humoral (secretin, cholecystokinin) and reflex. 1*moral mechanism at de-. Tei plays the greatest role in the process of regulation of digestion.

Liver- a soft, but dense organ of red-brown color, consists of four lobes: a large right lobe, a smaller left one and much smaller caudate and square lobes, forming the posterior lower surface of the liver; is located in the right hypochondrium. The mass of the liver in an adult is about 1.5 kg.

The liver is the most complex "chemical laboratory" and is a multifunctional link in homeostasis. The liver is involved in the following processes: | ■ digestion.- hepatocytes produce bile;

carbohydrate metabolism - supports normal level blood sugar due to the processes of glycogenesis, i.e., the conversion of glucose into glycogen using the hormone insulin; with a decrease in blood sugar, glycogen deposited in the liver is again converted into glucose (glycogenolysis); protein metabolism - participates in the metabolism of proteins, deamination of amino acids, neutralization of ammonia and its conversion into urea and creatinine, which are excreted by the kidneys; produces blood plasma proteins (albumins, y- and (3-globulins);

fat metabolism - synthesizes fatty acids, triglycerides, phospholipids, cholesterol, ketone bodies and participates in their metabolism; extracts lipids from the blood and is responsible for their oxidation in other tissues; inactivation of hormones - steroids, protein-peptide hormones, amino acid derivatives;

"vitamin metabolism - participates in the metabolism, absorption in the intestine of water- and fat-soluble vitamins A, D, E, K;

■ deposition of vitamins A, D, B 2 , B 6 , B 12 , C, K, folic and pantothenic acid (vitamin A is stored in the liver for about 10 months, vitamin D - 3-4 months; vitamin B n - from 1 year to several years);

■ deposition of trace elements - iron (in the form of ferritin), zinc, copper, manganese, molybdenum, cobalt, etc.;

■ blood deposition - 1.2 liters of blood flows through the liver in 1 minute, 70% of which comes from the organs of the digestive tract;

■ blood coagulation - synthesizes proteins fibrinogen, prothrombin, etc.;
"destruction of red blood cells;

■ neutralization (detoxification) of toxic substances - ammonia, indo
la, skatol, phenol, alcohol, xenobiotics, etc.

Liver cells in children are smaller than in adults. Lobularity of the liver is detected already by the first year of life. The liver is rich in iron. In eight-year-old children, the liver has almost the same structure as in an adult. However, the relative size of the liver in children is larger than in adults.

Bile formation is observed already in a three-month-old fetus. The intensity of bile formation and bile secretion increases with age. Bile is poor in bile acids, cholesterol, lecithin and salts, but rich in water, mucin, pigments, and during the neonatal period, urea. The amount of separated bile in a child, according to its weight, is 4 times greater than in an adult.

Small intestine- the longest section of the digestive tract, located between the exit from the stomach and the beginning of the large intestine. The length of the small intestine in an adult is 5-7 m, diameter 3.0-3.5 cm.

In the small intestine, the main processes of digestion of food take place and the process of digestion ends, which began in the stomach and duodenum (the initial section of the small intestine). Enzymes in the intestinal juice of the small intestine provide the final breakdown of nutrients.

The small intestine begins with the duodenum, which passes into the lean, continuing into the ileum.

The small intestine of an infant is relatively longer than that of adolescents, has a well-developed mucous membrane with a weak muscular layer.

The villi of the small intestines and the lymphatic apparatus are well developed, myelination of the nerve plexuses is not yet complete, the enzymatic power of the digestive glands in newborns is insignificant, but increases with age. Intestinal juice contains all the necessary enzymes for intestinal digestion, but they are less active in contrast to the older age.

The composition of the intestinal juice: mucus - 40-50%, NaHC0 3 - 2%, NaCl - 0.6% (alkaline juice reaction, ranges from 7.3 to 7,6); about 22 enzymes - erepsin, lipase, amylase, maltase, sucrase, nuclease, enterokinase, alkaline phosphatase.

Thus, the weak development of the muscle layer and elastic fibers in the buccal wall, the tenderness of the mucous membrane and the richness of its blood. OS, good development of the villi and folding of the mucous membrane with some insufficiency of the secretory apparatus and, finally, incomplete development of the nerve pathways are the most important anatomical and physiological features of the children's intestines. These features contribute to the emergence of functional disorders of motility and secretion in children.

Regulation of intestinal secretion is carried out by reflex and humoral
way.<

Colon located between the small intestine and the anus. It begins with the caecum, which has a appendix (appendix), then continues into the colon (ascending, transverse, descending), then into the sigmoid colon and ends with the rectum. The total length of the large intestine in an adult is 1.5-2.0 m, the width in the upper sections is 7 cm, in the lower sections it is about 4 cm.

Along the wall of the large intestine there are three trodol muscle bands,
constricting it and forming swellings. The mucous membrane of the large intestine
has folds, villi are absent. ".

Food enters the large intestine almost completely digested, with the exception of dietary fiber and very small amounts of proteins, fats and carbohydrates. In this section of the gastrointestinal tract, water is mainly absorbed (1.0-1.5 l / day), due to which a certain level of water-salt metabolism is maintained in the body. Absorption of nutrients in the large intestine is not essential.

There is no rotting in the intestines in healthy infants during the first months of life, they do not form such poisonous products as indole, skatole, phenol, etc. In the intestines of older children, fermentation and putrefaction processes simultaneously occur, the nature and intensity of which depends on the characteristics of the food and bacterial flora of the intestine.

The transit time of food through the gastrointestinal tract depends on the relative length of the digestive tract, as well as on the type of feeding:

■ breastfeeding - 13 hours;
1 ■ mixed feeding - 14.5 hours;

■ artificial feeding - 16 hours;

. * giving vegetables - 15 hours.

The breakdown of food, begun in the mouth and stomach, continues in the intestines. Peptones and other proteins that are not digested in the stomach undergo further digestion, due to which these proteins are broken down to the stage of amino acids, in part - to the stage of polypeptides of varying complexity. The latter undergo hydrolysis due to the action of erepsin. The action of trypsin in children is more significant than that of pepsin, since peptic digestion at an early age is of secondary importance.

Gastric, pancreatic and intestinal lipase, in combination with lipase of women's milk, breaks down fats into fatty acids and glycerol.

Since the digestive system and the enzymatic apparatus are not sufficiently developed, the child needs a kind of nutrition, especially in the lane. your year of life. It is necessary to observe the frequency of feeding the child during the day, take into account the amount and chemical composition of the milk that the child consumes.

In the embryonic period, the main thing is the histiotrophic nutrition of the embryo (the secret of the mucous membrane of the uterus, the material of the yolk sac).

From the 2-3rd month of intrauterine development, hemotrophic nutrition begins due to the transplacental transport of nutrients. From the 16-20th week they begin to function, which is the beginning of amniotrophic nutrition.

Depending on the formation of individual enzyme nutrition systems, the fetus begins to enterally receive protein, glucose, water, mineral salts, etc. The rate of differentiation and maturation of the digestive organs increases rapidly, but the relative immaturity of this system still remains until the time of birth. Lactotrophic nutrition is the most important stage in the adaptation of a newborn child; it allows resolving the contradiction between the very large needs of a rapidly growing organism and the low degree of functional development of the apparatus of distant digestion.

All parts of the digestive system in newborns are adapted to natural feeding with mother's milk. The oral cavity of a child in the 1st year of life is relatively small, the palate is flattened. Fat bodies of the cheeks are well expressed, roller-like thickening on the gums, transverse folds on the mucous membrane of the lips, which are also of great importance for the act of sucking. The mucous membrane of the oral cavity is dryish, rich in blood vessels, and very vulnerable. The secretion of saliva is provided by the submandibular, sublingual, parotid and numerous small glands. In the first 3 months of life, the secretion of saliva is insignificant, however, under its influence, the digestion of carbohydrates and the coagulation of milk casein already begin in the oral cavity. The esophagus is funnel-shaped, its length is equal to half the length (10 cm); in adolescents it reaches 25 cm. in a newborn child it is round, its capacity is 30-35 ml, at the age of 7-11 years the stomach is similar in shape to the stomach of an adult, its capacity grows to 1020 ml. The motor function of the stomach consists of peristaltic movements and periodic zmikan and openings of the goalkeeper. The acidity and enzymatic activity of the gastric glands is low, but 1/3 of the fat (emulsified by lactic lipase) is hydrolyzed in the stomach under the action of gastric lipase. In the stomach, the protein is partially hydrolyzed mainly due to such proteolytic enzymes as chymosin (renin, labenzyme, rennet), gastrixin; a small amount of salt, water, glucose is absorbed. Histological differentiation of the stomach continues until the end of the 2nd year of life.

The pancreas is the main gland of the digestive tract, its secretion increases especially rapidly after the introduction of complementary foods (complementary foods) and reaches the level of an adult at the age of 5 years. Main pancreatic enzymes: trypsin, chymotrypsin, diastase, amylase, lipase, phospholipase, endocrine insulin.

The liver of a newborn is relatively large, makes up 4-4.4% of body weight, is well vascularized, has insufficiently developed connective tissue and poorly demarcated lobules, functionally immature. The function of glycogen digestion is well manifested and not enough - detoxification. The liver is involved in the processes of digestion, hematopoiesis, blood circulation and metabolism. Bile in the first months of a child's life is formed in a small amount, contains some bile acids (which sometimes leads to steatorrhea in newborns), a lot of water, mucin, pigments; newborns also have a lot of urea. It also contains more taurocholic acid than glycocholic acid, which enhances its bactericidal properties, stimulates pancreatic secretion, and enhances colon peristalsis.

The intestines of an infant are relatively longer, than an adult, they are 6 times the length of her body. The intestinal mucosa is delicate, rich in villi, blood vessels, and cellular elements. Lymph nodes are well developed. The caecum and appendix are movable, the descending colon is longer than the ascending one. The rectum is relatively long, with weakly fixed mucosa and submucosa. The intestines of the child perform digestive, motor and suction functions. Intestinal juice is less active compared to the juice of an adult, it must be slightly acidic or neutral, then alkaline. Contains the enzymes enterokinase, alkaline phosphatase, amylase, lactase, maltase, invertase, and subsequently lipase. hydrolysis products, formed as a result of cavity (distant) and membrane (parietal) digestion, are absorbed by all parts of the small intestine, unlike adults. Of great importance in childhood is intracellular digestion with an easy transition of milk lactoglobulin unchanged into the blood. Water is absorbed in the large intestine, feces are formed, and mucus is secreted. A feature of the intestines in children is a relatively weak but long mesentery, which creates favorable conditions for the development of intussusception.

The digestive system of a full-term newborn is characterized by relative functional immaturity.

Characterized by a small capacity of the oral cavity and stomach, low content of specific enzymes in saliva, weak digestion of the stomach.

The stomach is in a state of physiological hypertonicity. The cardial section of the stomach is poorly developed, and the pyloric section is well developed, which creates prerequisites for the occurrence of regurgitation when overfeeding and swallowing air by the child. Motility of the stomach in newborns is slowed down, peristalsis is sluggish. The period of evacuation of food from the stomach depends on the type of food. Women's milk is in the baby's stomach for 2-3 hours, and adapted mixtures - 3-4 hours, which indicates the difficulties of digesting the latter and the need to switch to more rare feedings. Acid formation in the stomach of a newborn is low. Immediately after birth, there is a short-term "acidification" (due to lactic acid) of the stomach environment (pH=2.0), which performs a barrier role in the development of the gastrointestinal tract biocenosis, followed by the establishment of pH at the level of 4-6.

The functionality of the pancreas is limited. The lipolytic activity of digestive juices provides lipolysis of breast milk fat. Low levels of activity of pancreatic amylase and lipase are noted.

The length of the small intestine relative to height in newborns is one third longer than in adults. The small intestine is the main organ involved in the digestion and absorption of food. Lactase activity is 10 times higher than in adults.

The child is born with a sterile gastrointestinal tract. The aseptic phase lasts 10-20 hours, then the phase of "settlement" by microorganisms begins. Lactobacilli predominate in the upper gastrointestinal tract. Bifidoflora populates the intestine by the end of the 1st week of life. Normal biocenosis and intestinal barrier function are supported by immunoglobulins, lysozyme and a number of other protective factors of mother's milk. In the case of transferring a child to artificial or mixed feeding, the representation of Escherichia coli and enterococci increases, and the number of bifidobacteria decreases. Early attachment of the baby to the breast makes pathological colonization by microbes less likely.

17. AFO of the urinary system of a newborn.

In newborns, the following anatomical and physiological features are most pronounced:

The kidneys are relatively large, have a rounded shape, located;

The kidneys have a lobed structure and a relatively thin cortical layer;

The tubules and loop of Henle are relatively shorter, their lumen is narrower than in older children;

The pelvis is located intrarenally;

There is a close connection between the lymphatic vessels of the kidneys and intestines, which creates the prerequisites for the spread of infection from the intestines;

The diameter of the ureters is relatively large, they are curved, the muscular and elastic elements in the walls of the ureters are poorly developed, vesicoureteral reflux often occurs;

The bladder is located in the suprapubic region;

The urethra is relatively short (especially in girls);

The concentration function of the kidneys is low;

The kidneys are not able to excrete excess salts when excessive amounts are administered, which explains the tendency of newborns to edema;

Excretion by the kidneys of water is limited;

The bladder capacity is 30 ml, the frequency of urination is 20-25/day, the daily diuresis is 250 ml, the relative density of urine is 1.005-1.010.

In the extrauterine period, the gastrointestinal tract is the only source of obtaining nutrients and water necessary both for maintaining life and for the growth and development of the fetus.

Features of the digestive system in children

Anatomical and physiological features of the digestive system

Young children (especially newborns) have a number of morphological features common to all parts of the gastrointestinal tract:

• thin, tender, dry, easily injured mucous membrane;
• richly vascularized submucosal layer, consisting mainly of loose fiber;
• underdeveloped elastic and muscle tissue;
• low secretory function of the glandular tissue that separates a small amount of digestive juices with a low content of enzymes.

These features of the digestive system make it difficult to digest food if the latter does not correspond to the age of the child, reduce the barrier function of the gastrointestinal tract and lead to frequent diseases, create the preconditions for a general systemic reaction to any pathological effect and require very careful and thorough care of the mucous membranes.

Child's oral cavity

In a newborn and a child in the first months of life, the oral cavity has a number of features that ensure the act of sucking. These include: a relatively small volume of the oral cavity and a large tongue, good development of the muscles of the mouth and cheeks, roller-like duplication of the mucous membrane of the gums and transverse folds on the mucous membrane of the lips, fat bodies (Bish's lumps) in the thickness of the cheeks, which are characterized by significant elasticity due to the predominance of they contain solid fatty acids. The salivary glands are underdeveloped. However, insufficient salivation is mainly due to the immaturity of the nerve centers that regulate it. As they mature, the amount of saliva increases, and therefore, at the age of 3-4 months, the child often has the so-called physiological salivation due to the automatism of swallowing it that has not yet been developed.

In newborns and infants, the oral cavity is relatively small. The lips of newborns are thick, on their inner surface there are transverse ridges. The circular muscle of the mouth is well developed. The cheeks of newborns and young children are rounded and convex due to the presence between the skin and the well-developed buccal muscle of a rounded fatty body (Bish's fat lumps), which subsequently, starting from the age of 4, gradually atrophies.

The hard palate is flat, its mucous membrane forms weakly expressed transverse folds, and is poor in glands. The soft palate is relatively short, located almost horizontally. The palatine curtain does not touch the posterior pharyngeal wall, which allows the child to breathe during sucking. With the appearance of milk teeth, a significant increase in the size of the alveolar processes of the jaws occurs, and the arch of the hard palate rises, as it were. The tongue of newborns is short, wide, thick and inactive; well-defined papillae are visible on the mucous membrane. The tongue occupies the entire oral cavity: when the oral cavity is closed, it comes into contact with the cheeks and hard palate, protrudes forward between the jaws in the vestibule of the mouth.

The mucous membrane of the oral cavity

The mucous membrane of the oral cavity in children, especially at an early age, is thin and easily vulnerable, which must be taken into account when treating the oral cavity. The mucous membrane of the bottom of the oral cavity forms a noticeable fold, covered with a large number of villi. A protrusion in the form of a roller is also present on the mucous membrane of the cheeks in the gap between the upper and lower jaws. In addition, there are transverse folds (rollers) on the hard palate, roller-like thickenings on the gums. All these formations provide sealing of the oral cavity in the process of sucking. On the mucous membrane in the area of ​​the hard palate along the midline in newborns there are Bohn's nodules - yellowish formations - retention cysts of the salivary glands, disappearing by the end of the first month of life.

The mucous membrane of the oral cavity in children of the first 3-4 months of life is relatively dry, which is due to the insufficient development of the salivary glands and the deficiency of saliva. The salivary glands (parotid, submandibular, sublingual, small glands of the oral mucosa) in the newborn are characterized by low secretory activity and secrete a very small amount of thick, viscous saliva necessary for gluing the lips and sealing the oral cavity during sucking. The functional activity of the salivary glands begins to increase at the age of 1.52 months; in 34-month-old children, saliva often flows out of the mouth due to the immaturity of the regulation of salivation and swallowing of saliva (physiological salivation). The most intensive growth and development of the salivary glands occurs between the ages of 4 months and 2 years. By the age of 7, a child produces as much saliva as an adult. The reaction of saliva in newborns is often neutral or slightly acidic. From the first days of life, saliva contains osamylase and other enzymes necessary for the breakdown of starch and glycogen. In newborns, the concentration of amylase in saliva is low; during the first year of life, its content and activity increase significantly, reaching a maximum level at 2-7 years.

Throat and larynx in a child

The pharynx of a newborn has the shape of a funnel, its lower edge is projected at the level of the intervertebral disc between C I | and C 1 V . By adolescence, it descends to the level C vl -C VII. The larynx in infants also has a funnel-shaped shape and is located differently than in adults. The entrance to the larynx is located high above the lower posterior edge of the palatine curtain and is connected to the oral cavity. Food moves to the sides of the protruding larynx, so the baby can breathe and swallow at the same time without interrupting sucking.

Sucking and swallowing in a child

Sucking and swallowing are innate unconditioned reflexes. In healthy and mature newborns, they are already formed by the time of birth. When suckling, the baby's lips tightly grasp the nipple of the breast. The jaws squeeze it, and the communication between the oral cavity and the outside air stops. Negative pressure is created in the child's oral cavity, which is facilitated by the lowering of the lower jaw along with the tongue down and back. Then breast milk enters the rarefied space of the oral cavity. All elements of the masticatory apparatus of a newborn are adapted for the process of breast sucking: the gingival membrane, pronounced palatine transverse folds and fatty bodies in the cheeks. The adaptation of the oral cavity of the newborn to sucking is also physiological infantile retrognathia, which later turns into orthognathia. In the process of sucking, the child makes rhythmic movements of the lower jaw from front to back. The absence of the articular tubercle facilitates the sagittal movements of the child's mandible.

Child's esophagus

The esophagus is a spindle-shaped muscular tube lined from the inside with a mucous membrane. By birth, the esophagus is formed, its length in a newborn is 10-12 cm, at the age of 5 years - 16 cm, and at 15 years - 19 cm. The ratio between the length of the esophagus and body length remains relatively constant and is approximately 1:5. The width of the esophagus in a newborn is 5-8 mm, at 1 year old - 10-12 mm, by 3-6 years old - 13-15 mm and by 15 years old - 18-19 mm. The dimensions of the esophagus must be taken into account during fibro-esophago-gastroduodenoscopy (FEGDS), duodenal sounding and gastric lavage.

Anatomical narrowing of the esophagus in newborns and children of the first year of life is weakly expressed and is formed with age. The wall of the esophagus in a newborn is thin, the muscular membrane is poorly developed, it grows intensively up to 12-15 years. The mucous membrane of the esophagus in infants is poor in glands. Longitudinal folds appear at the age of 2-2.5 years. The submucosa is well developed, rich in blood vessels.

Outside the act of swallowing, the passage of the pharynx into the esophagus is closed. Peristalsis of the esophagus occurs during swallowing movements.

Gastrointestinal tract and size of the esophagus in children depending on age.

During anesthesia and intensive care, probing of the stomach is often performed, so the anesthesiologist must know the age dimensions of the esophagus (table).

Table. The size of the esophagus in children depending on age

In young children, there is a physiological weakness of the cardiac sphincter and, at the same time, a good development of the muscle layer of the pylorus. All this predisposes to regurgitation and vomiting. This must be remembered during anesthesia, especially with the use of muscle relaxants, since in these cases regurgitation is possible - a passive (and therefore late noticed) leakage of the contents of the stomach, which can lead to its aspiration and the development of severe aspiration pneumonia.

The capacity of the stomach increases in proportion to age up to 1-2 years. A further increase is associated not only with the growth of the body, but also with the peculiarities of nutrition. Approximate values ​​of the capacity of the stomach in newborns and infants are presented in the table.

Table. Gastric capacity in young children

What is the size of the esophagus in children?

These values ​​are very approximate, especially in pathological conditions. For example, with obstruction of the upper gastrointestinal tract, the walls of the stomach can stretch, which leads to an increase in its capacity by 2-5 times.

The physiology of gastric secretion in children of different ages, in principle, does not differ from that in adults. The acidity of the gastric juice may be somewhat lower than in adults, but this often depends on the nature of the diet. pH of gastric juice in infants is 3.8-5.8, in adults at the height of digestion up to 1.5-2.0.

Motility of the stomach under normal conditions depends on the nature of nutrition, as well as on neuroreflex impulses. High activity of the vagus nerve stimulates gastrospasm, and the splanchnic nerve stimulates pyloric spasm.

The time of passage of food (chyme) through the intestines in newborns is 4-18 hours, in older children - up to a day. Of this time, 7-8 hours are spent passing through the small intestine and 2-14 hours through the large intestine. With artificial feeding of infants, the digestion time can reach up to 48 hours.

baby stomach

Features of the stomach of a child

The stomach of a newborn has the shape of a cylinder, a bull horn or a fishhook and is located high (the inlet of the stomach is at the level of T VIII -T IX, and the pyloric opening is at the level of T x1 -T x | 1). As the child grows and develops, the stomach descends, and by the age of 7 years, its inlet (with the body upright) is projected between T X | and T X|| , and the output - between T x || and L. In infants, the stomach is located horizontally, but as soon as the child begins to walk, it gradually assumes a more vertical position.

Cardiac part, fundus and pyloric part of the stomach in a newborn are weakly expressed, the pylorus is wide. The inlet part of the stomach is often located above the diaphragm, the angle between the abdominal part of the esophagus and the wall of the fundus of the stomach adjacent to it is not sufficiently pronounced, the muscular membrane of the cardial part of the stomach is also poorly developed. Gubarev's valve (a fold of the mucous membrane protruding into the esophageal cavity and preventing the return of food) is almost not expressed (it develops by 8-9 months of life), the cardiac sphincter is functionally defective, while the pyloric part of the stomach is functionally well developed already at birth.

These features determine the possibility of reflux of the contents of the stomach into the esophagus and the development of peptic lesions of its mucous membrane. In addition, the tendency of children of the first year of life to regurgitation and vomiting is associated with the absence of a tight grasp of the esophagus by the legs of the diaphragm, as well as impaired innervation with increased intragastric pressure. Swallowing air during sucking (aerophagia) also contributes to regurgitation with improper feeding technique, a short frenulum of the tongue, greedy sucking, and too rapid release of milk from the mother's breast.

In the first weeks of life, the stomach is located in an oblique frontal plane, completely covered in front by the left lobe of the liver, and therefore the fundus of the stomach in the supine position is located below the antral-pyloric section, therefore, to prevent aspiration after feeding, children should be given an elevated position. By the end of the first year of life, the stomach lengthens, and in the period from 7 to 11 years, it acquires a shape similar to that of an adult. By the age of 8, the formation of its cardiac part is completed.

The anatomical capacity of the stomach of a newborn is 30-35 cm3, by the 14th day of life it increases to 90 cm3. Physiological capacity is less than anatomical, and on the first day of life is only 7-10 ml; by the 4th day after the start of enteral nutrition, it increases to 40-50 ml, and by the 10th day - up to 80 ml. Subsequently, the capacity of the stomach increases monthly by 25 ml and by the end of the first year of life is 250-300 ml, and by 3 years - 400-600 ml. An intensive increase in the capacity of the stomach begins after 7 years and by 10-12 years is 1300-1500 ml.

The muscular membrane of the stomach in a newborn is poorly developed, it reaches its maximum thickness only by the age of 15-20. The mucous membrane of the stomach in a newborn is thick, the folds are high. During the first 3 months of life, the surface of the mucous membrane increases by 3 times, which contributes to better digestion of milk. By the age of 15, the surface of the gastric mucosa increases 10 times. With age, the number of gastric pits increases, into which openings of the gastric glands open. By birth, the gastric glands are morphologically and functionally underdeveloped, their relative number (per 1 kg of body weight) in newborns is 2.5 times less than in adults, but rapidly increases with the onset of enteral nutrition.

The secretory apparatus of the stomach in children of the first year of life is underdeveloped, its functional abilities are low. The gastric juice of an infant contains the same components as the gastric juice of an adult: hydrochloric acid, chymosin (curdles milk), pepsins (break down proteins into albumoses and peptones) and lipase (breaks down neutral fats into fatty acids and glycerol).

Children in the first weeks of life are characterized by a very low concentration of hydrochloric acid in gastric juice and its low total acidity. It increases significantly after the introduction of complementary foods, i. when switching from lactotrophic nutrition to normal. In parallel with the decrease in the pH of gastric juice, the activity of carbonic anhydrase, which is involved in the formation of hydrogen ions, increases. In children of the first 2 months of life, the pH value is mainly determined by the hydrogen ions of lactic acid, and subsequently by hydrochloric acid.

The synthesis of proteolytic enzymes by the chief cells begins in the antenatal period, but their content and functional activity in newborns are low and gradually increase with age. The leading role in the hydrolysis of proteins in newborns is played by fetal pepsin, which has a higher proteolytic activity. In infants, significant fluctuations in the activity of proteolytic enzymes were noted depending on the nature of feeding (with artificial feeding, activity indicators are higher). In children of the first year of life (unlike adults), a high activity of gastric lipase is noted, which ensures the hydrolysis of fats in the absence of bile acids in a neutral environment.

Low concentrations of hydrochloric acid and pepsins in the stomach in newborns and infants determine the reduced protective function of gastric juice, but at the same time contribute to the preservation of Ig, which come with mother's milk.

In the first months of life, the motor function of the stomach is reduced, peristalsis is sluggish, and the gas bubble is enlarged. The frequency of peristaltic contractions in newborns is the lowest, then it actively increases and after 3 years it stabilizes. By the age of 2, the structural and physiological features of the stomach correspond to those of an adult. In infants, an increase in the tone of the muscles of the stomach in the pyloric region is possible, the maximum manifestation of which is pylorospasm. At an older age, cardiospasm is sometimes observed. The frequency of peristaltic contractions in newborns is the lowest, then it actively increases and after 3 years it stabilizes.

In infants, the stomach is horizontal, with the pyloric portion near the midline and the lesser curvature facing posteriorly. As the child begins to walk, the axis of the stomach becomes more vertical. By the age of 7-11, it is located in the same way as in adults. The capacity of the stomach in newborns is 30 - 35 ml, by the age of 1 it increases to 250 - 300 ml, by the age of 8 it reaches 1000 ml. The cardiac sphincter in infants is very poorly developed, and the pyloric one functions satisfactorily. This contributes to the regurgitation often observed at this age, especially when the stomach is distended due to swallowing air during sucking ("physiological aerophagia"). In the gastric mucosa of young children, there are fewer glands than in adults. And although some of them begin to function even in utero, in general, the secretory apparatus of the stomach in children of the first year of life is underdeveloped and its functional abilities are low. The composition of gastric juice in children is the same as in adults (hydrochloric acid, lactic acid, pepsin, rennet, lipase, sodium chloride), but the acidity and enzyme activity are much lower, which not only affects digestion, but also determines a low barrier stomach function. This makes it absolutely necessary to carefully observe the sanitary and hygienic regime during feeding of children (breast toilet, clean hands, proper expression of milk, sterility of nipples and bottles). In recent years, it has been established that the bactericidal properties of gastric juice are provided by lysozyme produced by the cells of the superficial epithelium of the stomach.

The maturation of the secretory apparatus of the stomach occurs earlier and more intensively in formula-fed children, which is associated with the body's adaptation to more indigestible food. The functional state and enzymatic activity depend on many factors: the composition of the ingredients and their quantity, the child's emotional tone, his physical activity, and his general condition. It is well known that fats suppress gastric secretion, while proteins stimulate it. Depressed mood, fever, intoxication are accompanied by a sharp decrease in appetite, i.e., a decrease in the secretion of gastric juice. Absorption in the stomach is insignificant and mainly concerns substances such as salts, water, glucose, and only partially - protein breakdown products. Motility of the stomach in children of the first months of life is slowed down, peristalsis is sluggish, the gas bubble is enlarged. The timing of the evacuation of food from the stomach depends on the nature of feeding. So, women's milk lingers in the stomach for 2-3 hours, cow's - for a longer time (3-4 hours and even up to 5 hours, depending on the buffer properties of milk), which indicates the difficulties of digesting the latter and the need to switch to more rare feedings.

Child's intestines

The intestine starts from the pylorus and ends at the anus. Distinguish between small and large intestines. The small intestine is divided into duodenum, jejunum and ileum; large intestine - on the blind, colon (ascending, transverse, descending, sigmoid) and rectum. The relative length of the small intestine in a newborn is large: 1 m per 1 kg of body weight, while in adults it is only 10 cm.

In children, the intestines are relatively longer than in adults (in an infant, it exceeds the length of the body by 6 times, in adults, by 4 times), but its absolute length varies individually within wide limits. The caecum and appendix are mobile, the latter is often located atypically, thereby making it difficult to diagnose inflammation. The sigmoid colon is relatively longer than in adults, and in some children even forms loops, which contributes to the development of primary constipation. With age, these anatomical features disappear. Due to the weak fixation of the mucous and submucosal membranes of the rectum, it may prolapse with persistent constipation and tenesmus in debilitated children. The mesentery is longer and easily stretchable, and therefore torsion, intussusception, etc., easily occur. The omentum in children under 5 years of age is short, so the possibility of localizing peritonitis in a limited area of ​​​​the abdominal cavity is almost excluded. Of the histological features, it should be noted the good severity of the villi and the abundance of small lymphatic follicles.

All intestinal functions (digestive, absorption, barrier and motor) in children differ from those of adults. The process of digestion, which begins in the mouth and stomach, continues in the small intestine under the influence of pancreatic juice and bile secreted into the duodenum, as well as intestinal juice. The secretory apparatus of the intestinal tract is generally formed by the time of the birth of the child, and even in the smallest children, the same enzymes are determined in the intestinal juice as in adults (enterokinase, alkaline phosphatase, erepsin, lipase, amylase, maltase, lactase, nuclease), but significantly less active. Only mucus is secreted in the large intestine. Under the influence of intestinal enzymes, mainly the pancreas, there is a breakdown of proteins, fats and carbohydrates. The process of digestion of fats is especially intense due to the low activity of lipolytic enzymes.

In children who are breastfed, lipids emulsified by bile are cleaved by 50% under the influence of maternal milk lipase. Digestion of carbohydrates occurs in the small intestine parietal under the influence of pancreatic juice amylase and 6 disaccharidases localized in the brush border of enterocytes. In healthy children, only a small part of the sugars is not subjected to enzymatic breakdown and is converted in the large intestine to lactic acid by bacterial decomposition (fermentation). The processes of putrefaction in the intestines of healthy infants do not occur. Hydrolysis products formed as a result of cavitary and parietal digestion are absorbed mainly in the small intestine: glucose and amino acids into the blood, glycerol and fatty acids into the lymph. In this case, both passive mechanisms (diffusion, osmosis) and active transport with the help of carrier substances play a role.

The structural features of the intestinal wall and its large area determine in young children a higher absorption capacity than in adults and, at the same time, an insufficient barrier function due to the high permeability of the mucous membrane for toxins, microbes and other pathogenic factors. The constituent components of human milk are most easily absorbed, the protein and fats of which in newborns are partially absorbed unsplit.

The motor (motor) function of the intestines is carried out in children very energetically due to pendulum movements that mix food, and peristaltic, moving food to the exit. Active motility is reflected in the frequency of bowel movements. In infants, defecation occurs reflexively, in the first 2 weeks of life up to 3-6 times a day, then less often, by the end of the first year of life it becomes an arbitrary act. In the first 2 to 3 days after birth, the baby excretes meconium (original feces) of a greenish-black color. It consists of bile, epithelial cells, mucus, enzymes, and swallowed amniotic fluid. The stools of healthy newborns who are on breastfeeding, have a mushy texture, golden-yellow color, sour smell. In older children, the chair is decorated, 1-2 times a day.

Child's duodenum

The duodenum of a newborn has an annular shape (bends are formed later), its beginning and end are located at the L level. In children older than 5 months, the upper part of the duodenum is at the level of T X | 1; the descending part gradually drops by the age of 12 to the level L IM L IV . In young children, the duodenum is very mobile, but by the age of 7, adipose tissue appears around it, which fixes the intestine, reducing its mobility.

In the upper part of the duodenum, acidic gastric chyme is alkalized, prepared for the action of enzymes that come from the pancreas and are formed in the intestine, and mixed with bile. The folds of the mucous membrane of the duodenum in newborns are lower than in older children, the duodenal glands are small, less branched than in adults. The duodenum has a regulatory effect on the entire digestive system through hormones secreted by the endocrine cells of its mucous membrane.

The small intestine of a child

The jejunum occupies approximately 2/5, and the ileum 3/5 of the length of the small intestine (excluding the duodenum). The ileum ends with an ileocecal valve (Bauhinian valve). In young children, relative weakness of the ileocecal valve is noted, and therefore the contents of the caecum, the richest in bacterial flora, can be thrown into the ileum, causing a high incidence of inflammatory lesions of its terminal section.

The small intestine in children occupies an unstable position, depending on the degree of its filling, the position of the body, the tone of the intestines and the muscles of the anterior abdominal wall. Compared with adults, the intestinal loops lie more compactly (due to the relatively large size of the liver and the underdevelopment of the small pelvis). After 1 year of life, as the pelvis develops, the location of the loops of the small intestine becomes more constant.

The small intestine of an infant contains a relatively large amount of gases, the volume of which gradually decreases until it disappears completely by the age of 7 (in adults, gases are normally absent in the small intestine).

The mucous membrane is thin, richly vascularized and has increased permeability, especially in children of the first year of life. Intestinal glands in children are larger than in adults. Their number increases significantly during the first year of life. In general, the histological structure of the mucous membrane becomes similar to that in adults by the age of 5-7 years. In newborns, single and group lymphoid follicles are present in the thickness of the mucous membrane. Initially, they are scattered throughout the intestine, and later they are grouped mainly in the ileum in the form of group lymphatic follicles (Peyer's patches). Lymphatic vessels are numerous, have a wider lumen than in adults. Lymph flowing from the small intestine does not pass through the liver, and the products of absorption enter directly into the blood.

The muscular coat, especially its longitudinal layer, is poorly developed in newborns. The mesentery in newborns and young children is short, increasing significantly in length during the first year of life.

In the small intestine, the main stages of the complex process of splitting and absorption of nutrients occur with the combined action of intestinal juice, bile and pancreatic secretions. The breakdown of nutrients with the help of enzymes occurs both in the cavity of the small intestine (abdominal digestion) and directly on the surface of its mucous membrane (parietal, or membrane, digestion, which dominates in infancy during the period of milk nutrition).

The secretory apparatus of the small intestine is generally formed by birth. Even in newborns, the same enzymes can be determined in the intestinal juice as in adults (enterokinase, alkaline phosphatase, lipase, amylase, maltase, nuclease), but their activity is lower and increases with age. The peculiarities of protein assimilation in young children include the high development of pinocytosis by epitheliocytes of the intestinal mucosa, as a result of which milk proteins in children in the first weeks of life can pass into the blood in an unmodified form, which can lead to the appearance of AT to cow's milk proteins. In children older than a year, proteins undergo hydrolysis to form amino acids.

Already from the first days of a child's life, all parts of the small intestine have a fairly high hydrolytic activity. Disaccharidases in the intestine appear even in the prenatal period. Maltase activity is quite high at birth and remains so in adults; sucrase activity increases somewhat later. In the first year of life, a direct correlation is observed between the age of the child and the activity of maltase and sucrase. Lactase activity increases rapidly in the last weeks of gestation, and after birth, the increase in activity decreases. It remains high throughout the period of breastfeeding, by the age of 4-5 there is a significant decrease in it, it is the smallest in adults. It should be noted that human milk rlactose is absorbed more slowly than cow's milk oslactose, and partially enters the large intestine, which contributes to the formation of gram-positive intestinal microflora in breastfed children.

Due to the low activity of lipase, the process of digesting fats is especially intense.

Fermentation in the intestines of infants complements the enzymatic breakdown of food. There is no rotting in the intestines of healthy children in the first months of life.

Absorption is closely related to parietal digestion and depends on the structure and function of the cells of the surface layer of the small intestine mucosa.

Large intestine of a child

The large intestine in a newborn has an average length of 63 cm. By the end of the first year of life, it lengthens to 83 cm, and subsequently its length is approximately equal to the height of the child. By birth, the colon does not complete its development. The newborn does not have omental processes (they appear on the 2nd year of the child's life), the bands of the colon are barely visible, the haustras of the colon are absent (they appear after 6 months). Colon bands, haustra and omental processes are finally formed by the age of 6-7 years.

The caecum in newborns has a conical or funnel-shaped shape, its width prevails over its length. It is located high (in a newborn directly under the liver) and descends into the right iliac fossa by the middle of adolescence. The higher the caecum, the more underdeveloped the ascending colon. The ileocecal valve in newborns looks like small folds. The ileocecal opening is annular or triangular, gaping. In children older than a year, it becomes slit-like. The appendix in a newborn has a conical shape, the entrance to it is wide open (the valve is formed in the first year of life). The appendix has great mobility due to the long mesentery and can be placed in any part of the abdominal cavity, including retrocecally. After birth, lymphoid follicles appear in the appendix, reaching their maximum development by 10-14 years.

The colon surrounds the loops of the small intestine. The ascending part of the newborn is very short (2-9 cm) and increases after the colon takes its final position. The transverse part of the colon in a newborn usually has an oblique position (its left bend is located higher than the right one) and only by the age of 2 takes a horizontal position. The mesentery of the transverse part of the colon in a newborn is short (up to 2 cm), within 1.5 years its width increases to 5-8.5 cm, due to which the intestine becomes able to move easily when the stomach and small intestine are filled. The descending part of the colon in a newborn has a smaller diameter than other parts of the colon. It is weakly mobile and rarely has a mesentery.

The sigmoid colon in a newborn is relatively long (12-29 cm) and mobile. Up to 5 years, it is located high in the abdominal cavity due to underdevelopment of the small pelvis, and then descends into it. Its mobility is due to the long mesentery. By the age of 7, the intestine loses its mobility as a result of the shortening of the mesentery and the accumulation of adipose tissue around it. The large intestine provides water resorption and evacuation-reservoir function. It completes the absorption of digested food, breaks down the remaining substances (both under the influence of enzymes coming from the small intestine and the bacteria that inhabit the large intestine), and the formation of feces occurs.

The mucous membrane of the large intestine in children is characterized by a number of features: deepened crypts, flatter epithelium, higher rate of its proliferation. Juice secretion of the colon under normal conditions is insignificant; however, it sharply increases with mechanical irritation of the mucous membrane.

The rectum of a child

The rectum of a newborn has a cylindrical shape, does not have an ampulla (its formation occurs in the first period of childhood) and bends (it is formed simultaneously with the sacral and coccygeal bends of the spine), its folds are not expressed. In children of the first months of life, the rectum is relatively long and poorly fixed, since fatty tissue is not developed. The rectum occupies the final position by 2 years. In a newborn, the muscular membrane is poorly developed. Due to the well-developed submucosa and weak fixation of the mucous membrane relative to the submucosa, as well as the insufficient development of the anal sphincter in young children, prolapse often occurs. The anus in children is located more dorsally than in adults, at a distance of 20 mm from the coccyx.

Functional features of the intestines of the child

The motor function of the intestine (motor) consists of pendulum movements that occur in the small intestine, due to which its contents are mixed, and peristaltic movements that move the chyme towards the large intestine. The colon is also characterized by anti-peristaltic movements, thickening and forming feces.

Motor skills in young children are more active, which contributes to frequent bowel movements. In infants, the duration of the passage of food gruel through the intestines is from 4 to 18 hours, and in older children - about a day. High motor activity of the intestine, combined with insufficient fixation of its loops, determines the tendency to intussusception.

Defecation in children

During the first hours of life, meconium (original feces) is passed - a sticky mass of dark green color with a pH of about 6.0. Meconium consists of desquamated epithelium, mucus, remnants of amniotic fluid, bile pigments, etc. On the 2nd-3rd day of life, feces are mixed with meconium, and from the 5th day, feces take on a characteristic appearance for a newborn. In children of the first month of life, defecation usually occurs after each feeding - 5-7 times a day, in children from the 2nd month of life - 3-6 times, in 1 year - 12 times. With mixed and artificial feeding, defecation is more rare.

Cal in children who are breastfed, mushy, yellow in color, sour reaction and sour smell; with artificial feeding, the feces have a thicker consistency (putty-like), lighter, sometimes with a grayish tint, neutral or even alkaline reaction, more pungent odor. The golden yellow color of feces in the first months of a child's life is due to the presence of bilirubin, greenish - biliverdin.

In infants, defecation occurs reflexively, without the participation of the will. From the end of the first year of life, a healthy child is gradually accustomed to the fact that defecation becomes an arbitrary act.

Pancreas

The pancreas, a parenchymal organ of external and internal secretion, is small in newborns: its mass is about 23 g, and its length is 4-5 cm. Already by 6 months, the mass of the gland doubles, by 1 year it increases by 4 times, and by 10 years - 10 times.

In a newborn, the pancreas is located deep in the abdominal cavity at the level of T x, i.e. higher than that of an adult. Due to weak fixation to the posterior wall of the abdominal cavity in a newborn, it is more mobile. In children of early and older age, the pancreas is at the level of L n . Iron grows most intensively in the first 3 years and in the puberty period.

By birth and in the first months of life, the pancreas is not sufficiently differentiated, abundantly vascularized and poor in connective tissue. At an early age, the surface of the pancreas is smooth, and by the age of 10-12, tuberosity appears, due to the isolation of the boundaries of the lobules. The lobes and lobules of the pancreas in children are smaller and few in number. The endocrine part of the pancreas is more developed at birth than the exocrine part.

Pancreatic juice contains enzymes that ensure the hydrolysis of proteins, fats and carbohydrates, as well as bicarbonates, which create the alkaline reaction of the environment necessary for their activation. In newborns, a small volume of pancreatic juice is secreted after stimulation, amylase activity and bicarbonate capacity are low. Amylase activity from birth to 1 year increases several times. When switching to a normal diet, in which more than half of the calorie requirement is covered by carbohydrates, amylase activity increases rapidly and reaches its maximum values ​​​​by 6-9 years. The activity of pancreatic lipase in newborns is low, which determines the great role of salivary gland lipase, gastric juice and breast milk lipase in the hydrolysis of fat. The activity of duodenal content lipase increases by the end of the first year of life, reaching the level of an adult by the age of 12. The proteolytic activity of the secret of the pancreas in children during the first months of life is quite high, it reaches a maximum at the age of 4-6 years.

The type of feeding has a significant effect on the activity of the pancreas: with artificial feeding, the activity of enzymes in the duodenal juice is 4-5 times higher than with natural feeding.

In a newborn, the pancreas is small (length 5-6 cm, by the age of 10 it is three times larger), located deep in the abdominal cavity, at the level of the X thoracic vertebra, in subsequent age periods - at the level of the I lumbar vertebra. It is richly vascularized, intensive growth and differentiation of its structure continues up to 14 years. The capsule of the organ is less dense than in adults, consists of fine-fibred structures, and therefore, in children with inflammatory edema of the pancreas, its compression is rarely observed. The excretory ducts of the gland are wide, which provides good drainage. Close contact with the stomach, the root of the mesentery, the solar plexus and the common bile duct, with which the pancreas in most cases has a common outlet to the duodenum, often leads to a friendly reaction from the organs of this zone with a wide irradiation of pain.

The pancreas in children, as in adults, has external and intrasecretory functions. The exocrine function is to produce pancreatic juice. It contains albumins, globulins, trace elements and electrolytes, as well as a large set of enzymes necessary for digestion of food, including proteolytic (trypsin, chymopsin, elastase, etc.), lipolytic (lipase, phospholipase A and B, etc.) and amylolytic (alpha- and beta-amylase, maltase, lactase, etc.). The rhythm of pancreatic secretion is regulated by neuro-reflex and humoral mechanisms. Humoral regulation is carried out by secretin, which stimulates the separation of the liquid part of pancreatic juice and bicarbonates, and pancreozymin, which enhances the secretion of enzymes along with other hormones (cholecystokinin, hepatokinin, etc.) produced by the mucous membrane of the duodenum and jejunum under the influence of hydrochloric acid. The secretory activity of the gland reaches the level of adult secretion by the age of 5. The total volume of separated juice and its composition depend on the amount and nature of the food eaten. The intrasecretory function of the pancreas is carried out by the synthesis of hormones (insulin, glucagon, lipocaine) involved in the regulation of carbohydrate and fat metabolism.

Liver in children

The size of the liver in children

The liver at the time of birth is one of the largest organs and occupies 1/3-1/2 of the volume of the abdominal cavity, its lower edge protrudes significantly from under the hypochondrium, and the right lobe can even touch the iliac crest. In newborns, the mass of the liver is more than 4% of body weight, and in adults - 2%. In the postnatal period, the liver continues to grow, but more slowly than body weight: the initial mass of the liver doubles by 8-10 months and triples by 2-3 years.

Due to the different rate of increase in the mass of the liver and body in children from 1 to 3 years of age, the edge of the liver comes out from under the right hypochondrium and is easily palpated 1-3 cm below the costal arch along the midclavicular line. From the age of 7, the lower edge of the liver does not come out from under the costal arch and is not palpable in a calm position; in the midline does not go beyond the upper third of the distance from the umbilicus to the xiphoid process.

The formation of liver lobules begins in the fetus, but by the time of birth, the liver lobules are not clearly demarcated. Their final differentiation is completed in the postnatal period. The lobulated structure is revealed only by the end of the first year of life.

The branches of the hepatic veins are located in compact groups and do not intersperse with the branches of the portal vein. The liver is plethoric, as a result of which it rapidly increases with infections and intoxications, circulatory disorders. The fibrous capsule of the liver is thin.

About 5% of the volume of the liver in newborns is accounted for by hematopoietic cells, subsequently their number decreases rapidly.

In the composition of the liver, the newborn has more water, but less protein, fat and glycogen. By the age of 8, the morphological and histological structure of the liver becomes the same as in adults.

Functions of the liver in the child's body

The liver performs various and very important functions:

• produces bile, which is involved in intestinal digestion, stimulates the motor activity of the intestine and sanitizes its contents;
• stores nutrients, mainly excess glycogen;
• performs a barrier function, protecting the body from exogenous and endogenous pathogenic substances, toxins, poisons, and takes part in the metabolism of medicinal substances;
• participates in the metabolism and conversion of vitamins A, D, C, B12, K;
• during fetal development is a hematopoietic organ.

The formation of bile begins already in the prenatal period, but bile formation at an early age is slowed down. With age, the ability of the gallbladder to concentrate bile increases. The concentration of bile acids in the hepatic bile in children of the first year of life is high, especially in the first days after birth, which leads to the frequent development of subhepatic cholestasis (bile thickening syndrome) in newborns. By the age of 4-10, the concentration of bile acids decreases, and in adults it increases again.

The neonatal period is characterized by the immaturity of all stages of the hepato-intestinal circulation of bile acids: insufficiency of their uptake by hepatocytes, excretion through the tubular membrane, slowing of bile flow, dyscholia due to a decrease in the synthesis of secondary bile acids in the intestine and a low level of their reabsorption in the intestine. Children produce more atypical, less hydrophobic, and less toxic fatty acids than adults. The accumulation of fatty acids in the intrahepatic bile ducts causes an increased permeability of intercellular junctions and an increased content of bile components in the blood. The bile of a child in the first months of life contains less cholesterol and salts, which determines the rarity of stone formation.

In newborns, fatty acids combine mainly with taurine (in adults - with glycine). Taurine conjugates are more soluble in water and less toxic. A relatively higher content of taurocholic acid in bile, which has a bactericidal effect, determines the rarity of the development of bacterial inflammation of the biliary tract in children of the first year of life.

Enzymatic systems of the liver, which provide adequate metabolism of various substances, are not mature enough at birth. Artificial feeding stimulates their earlier development, but leads to their disproportion.

After birth, the child's albumin synthesis decreases, which leads to a decrease in the albumin-globulin ratio in the blood.

In children, transamination of amino acids occurs much more actively in the liver: at birth, the activity of aminotransferases in the child's blood is 2 times higher than in the mother's blood. At the same time, the processes of transamination are not mature enough, and the number of essential acids for children is greater than for adults. So, in adults there are 8 of them, children under 5-7 years old need additional histidine, and children in the first 4 weeks of life also need cysteine.

The urea-forming function of the liver is formed by the age of 3-4 months; before that, children have a high excretion of ammonia in the urine at a low concentration of urea.

Children of the first year of life are resistant to ketoacidosis, although they receive a diet rich in fat, and at the age of 2-12 years, on the contrary, they are prone to it.

In a newborn, the content of cholesterol and its esters in the blood is much lower than in the mother. After the start of breastfeeding for 3-4 months, hypercholesterolemia is noted. In the next 5 years, the concentration of cholesterol in children remains lower than in adults.

In newborns in the first days of life, insufficient activity of glucuronyl transferase is noted, with the participation of which conjugation of bilirubin with glucuronic acid and the formation of water-soluble "direct" bilirubin occur. Difficulty in the excretion of bilirubin is the main cause of physiological jaundice in newborns.

The liver performs a barrier function, neutralizes endogenous and exogenous harmful substances, including toxins from the intestines, and takes part in the metabolism of medicinal substances. In young children, the neutralizing function of the liver is not sufficiently developed.

The functionality of the liver in young children is relatively low. Its enzymatic system is especially untenable in newborns. In particular, the metabolism of indirect bilirubin released during hemolysis of erythrocytes is incomplete, resulting in physiological jaundice.

Gallbladder in a child

The gallbladder in newborns is usually hidden by the liver, its shape can be different. Its dimensions increase with age, and by the age of 10-12 years, the length increases by about 2 times. The rate of excretion of gallbladder bile in newborns is 6 times less than in adults.

In newborns, the gallbladder is located deep in the thickness of the liver and has a spindle-shaped shape, its length is about 3 cm. It acquires a typical pear-shaped shape by 6-7 months and reaches the edge of the liver by 2 years.

The bile of children differs in composition from the bile of adults. It is poor in bile acids, cholesterol and salts, but rich in water, mucin, pigments, and in the neonatal period, in addition, urea. A characteristic and favorable feature of the bile of a child is the predominance of taurocholic acid over glycocholic acid, since taurocholic acid enhances the bactericidal effect of bile, and also accelerates the separation of pancreatic juice. Bile emulsifies fats, dissolves fatty acids, improves peristalsis.

The intestinal microflora of a child

During fetal development, the intestines of the fetus are sterile. Its colonization by microorganisms occurs first during the passage of the mother's birth canal, then through the mouth when children come into contact with surrounding objects. The stomach and duodenum contain a meager bacterial flora. In the small and especially the large intestine, it becomes more diverse, the number of microbes increases; microbial flora depends mainly on the type of feeding of the child. When breastfeeding, the main flora is B. bifidum, the growth of which is promoted by (3-lactose of human milk. When complementary foods are introduced into the diet or the child is transferred to cow's milk feeding, gram-negative Escherichia coli, which is a conditionally pathogenic microorganism, predominates in the intestine. therefore, dyspepsia is more common in formula-fed children.According to modern concepts, the normal intestinal flora performs three main functions:

Creation of an immunological barrier;

Final digestion of food residues and digestive enzymes;

Synthesis of vitamins and enzymes.

The normal composition of the intestinal microflora (eubiosis) is easily disturbed under the influence of infection, improper diet, as well as the irrational use of antibacterial agents and other drugs, leading to a state of intestinal dysbacteriosis.

Historical data on the intestinal microflora

The study of the intestinal microflora began in 1886, when F. Escherich described Escherichia coli (Bacterium coli centipae). The term "dysbacteriosis" was first introduced by A. Nissle in 1916. Later, the positive role of the normal intestinal microflora in the human body was proved by I. I. Mechnikov (1914), A. G. Peretz (1955), A. F. Bilibin (1967), V. N. Krasnogolovets (1968), A. S. Bezrukova (1975), A. A. Vorobyov et al. (1977), I.N. Blokhina et al. (1978), V. G. Dorofeichuk et al. (1986), B. A. Shenderov et al. (1997).

Characteristics of the intestinal microflora in children

The microflora of the gastrointestinal tract takes part in digestion, prevents the development of pathogenic flora in the intestine, synthesizes a number of vitamins, participates in the inactivation of physiologically active substances and enzymes, affects the rate of renewal of enterocytes, enterohepatic circulation of bile acids, etc.

The intestines of the fetus and newborn are sterile during the first 10-20 hours (aseptic phase). Then the colonization of the intestine by microorganisms begins (second phase), and the third phase - stabilization of the microflora - lasts at least 2 weeks. The formation of intestinal microbial biocenosis begins from the first day of life, by the 7-9th day in healthy full-term children, the bacterial flora is usually represented mainly by Bifidobacterium bifldum, Lactobacillus acidophilus. With natural feeding, B. bifidum prevails among the intestinal microflora, with artificial feeding, L. acidophilus, B. bifidum and enterococci are present in almost equal amounts. The transition to a diet typical for adults is accompanied by a change in the composition of the intestinal microflora.

Intestinal microbiocenosis

The center of the human microecological system is the intestinal microbiocenosis, which is based on the normal (indigenous) microflora, which performs a number of important functions:

Indigenous microflora:

• participates in the formation of colonization resistance;
• produces bacteriocins - antibiotic-like substances that prevent the reproduction of putrefactive and pathogenic flora;
• normalizes intestinal peristalsis;
• participates in the processes of digestion, metabolism, detoxification of xenobiotics;
• possesses universal immunomodulatory properties.

Distinguish mucoid microflora(M-microflora) - microorganisms associated with the intestinal mucosa, and cavity microflora(P-microflora) - microorganisms localized mainly in the intestinal lumen.

All representatives of the microbial flora with which the macroorganism interacts are divided into four groups: obligate flora (the main intestinal microflora); facultative (conditionally pathogenic and saprophytic microorganisms); transient (random microorganisms incapable of prolonged stay in the macroorganism); pathogenic (causative agents of infectious diseases).

Obligate microflora intestines - bifidobacteria, lactobacilli, full-fledged E. coli, propionobacteria, peptostreptococci, enterococci.

Bifidobacteria in children, depending on age, range from 90% to 98% of all microorganisms. Morphologically, they are gram-positive, immobile rods with club-shaped thickening at the ends and bifurcation at one or both poles, anaerobic, not forming spores. Bifidobacteria are divided into 11 species: B. bifidum, B. ado-lescentis, B. infantis, B. breve, B. hngum, B. pseudolongum, B. thermophilum, B. suis, B. asteroides, B. indu.

Dysbacteriosis is a violation of the ecological balance of microorganisms, characterized by a change in the quantitative ratio and qualitative composition of the indigenous microflora in the microbiocenosis.

Intestinal dysbacteriosis is a violation of the ratio between anaerobic and aerobic microflora towards a decrease in the number of bifidobacteria and lactobacilli, normal E. coli and an increase in the number of microorganisms found in small numbers or usually absent in the intestine (opportunistic microorganisms).

Methodology for the study of the digestive system

The state of the digestive organs is judged by complaints, the results of questioning the mother and the data of objective research methods:

examination and observation in dynamics;

palpation;

percussion;

laboratory and instrumental indicators.

Complaints of the child

The most common of these are complaints of abdominal pain, loss of appetite, regurgitation or vomiting, and bowel dysfunction (diarrhea and constipation).

Questioning a child

A doctor-directed questioning of the mother allows you to clarify the time of onset of the disease, its relationship with the characteristics of nutrition and regimen, past diseases, and family-hereditary nature. Of particular importance is the detailed clarification of feeding issues.

Abdominal pain is a common symptom that reflects a variety of childhood pathologies. Pain that arose for the first time requires, first of all, the exclusion of surgical pathology of the abdominal cavity - appendicitis, intussusception, peritonitis. They can also be caused by acute infectious diseases (influenza, hepatitis, measles), viral and bacterial intestinal infections, inflammation of the urinary tract, pleuropneumonia, rheumatism, pericarditis, Shenlein-Genoch disease, periarteritis nodosa. Recurrent abdominal pain in older children are observed in diseases such as gastritis, duodenitis, cholecystitis, pancreatitis, peptic ulcer of the stomach and duodenum, ulcerative colitis. Functional disorders and helminthic invasion can also be accompanied by abdominal pain.

Reduced or prolonged loss of appetite (anorexia) in children is often the result of psychogenic factors (school overload, family conflict, neuroendocrine dysfunction during puberty), including improper feeding of the child (forced feeding). However, usually a decrease in appetite indicates a low secretion of the stomach and is accompanied by trophic and metabolic disorders.

Vomiting and regurgitation in newborns and infants may be due to pyloric stenosis or pylorospasm. In healthy children of this age, aerophagia leads to frequent regurgitation, which is observed in violation of the feeding technique, a short frenulum of the tongue, and a tight chest in the mother. In children 2-10 years old, suffering from neuro-arthritic diathesis, acetonemic vomiting may periodically occur due to acute reversible metabolic disorders. Emergence of vomiting in connection with damage of TsNS, infectious diseases, poisonings is possible.

Diarrhea in children of the first year of life often reflects intestinal dysfunction due to qualitative or quantitative feeding errors, regimen violations, overheating (simple dyspepsia) or is accompanied by an acute febrile illness (parenteral dyspepsia), but can also be a symptom of enterocolitis with intestinal infection.

Constipation - rare bowel movements occurring after 48 hours or more. They can be the result of both a functional disorder (dyskinesia) of the large intestine, and its organic damage (congenital narrowing, anal fissures, Hirschsprung's disease, chronic colitis) or inflammatory diseases of the stomach, liver and biliary tract. Nutritional (food intake, poor fiber) and infectious factors are of some importance. Sometimes constipation is associated with the habit of delaying the act of defecation and the resulting violation of the tone of the lower segment of the colon, and in infants with chronic malnutrition (pyloric stenosis). In children with sufficient weight gain, breastfed, stools are sometimes rare due to good digestion and a small amount of toxins in the intestines.

When examining the abdomen, pay attention to its size and shape. In healthy children of different ages, it slightly protrudes above the level of the chest, and subsequently flattens somewhat. An increase in the size of the abdomen can be due to a number of reasons:

• hypotension of the muscles of the abdominal wall and intestines, which is especially often observed in rickets and dystrophies;
• flatulence that develops with diarrhea of ​​various etiologies, persistent constipation, intestinal dysbacteriosis, pancreatitis, pancreatic cystic fibrosis;
• an increase in the size of the liver and spleen in chronic hepatitis, systemic blood diseases, circulatory failure and other pathologies;
• the presence of fluid in the abdominal cavity due to peritonitis, ascites;
• neoplasm of the abdominal cavity and retroperitoneal space.

The shape of the abdomen also has a diagnostic value: its uniform increase is observed with flatulence, hypotension of the muscles of the anterior abdominal wall and intestines ("frog" abdomen - with rickets, celiac disease), local bulging with hepatolienal syndrome of various etiologies, tumors of the abdominal cavity and retroperitoneal space. Retraction of the abdomen can be observed when the child is starving, pyloric stenosis, meningitis, diphtheria. On examination, you can determine the condition of the navel in newborns, the expansion of the venous network in liver cirrhosis, the divergence of the muscles of the white line and hernial protrusions, and in malnourished children in the first months of life, intestinal motility, which increases with pyloric stenosis, intussusception and other pathological processes.

Palpation of the abdomen and abdominal organs of the child

Palpation of the abdomen and abdominal organs is best done in the position of the patient on his back with legs slightly bent, with a warm hand, starting from the navel, and it is necessary to try to distract the child's attention from this procedure. Superficial palpation is carried out with light tangential movements. It makes it possible to determine the condition of the skin of the abdomen, muscle tone and tension of the abdominal wall. With deep palpation, the presence of painful points, infiltrates is revealed, the dimensions, consistency, nature of the surface of the lower edge of the liver and spleen are determined, an increase in mesenteric lymph nodes in tuberculosis, lymphogranulomatosis, reticulosis and other diseases, spastic or atonic state of the intestine, accumulation of feces.

Palpation is also possible in the vertical position of the child with a half-tilt forward and lowered arms. At the same time, the liver and spleen are well probed, free fluid in the abdominal cavity is determined. In older children, bimanual palpation of the abdominal organs is used.

Percussion of the child's abdomen

Examination of the child's abdomen

Lastly, the child's mouth and pharynx are examined. At the same time, attention is paid to the smell from the mouth, the condition of the mucous membranes of the cheeks and gums (the presence of aphthae, ulcers, bleeding, fungal overlays, Filatov-Koplik spots), teeth, tongue (macroglossia with myxedema), papillary crimson - with scarlet fever, coated - with diseases of the gastrointestinal tract, "geographic" - with exudative-catarrhal diathesis, "varnished" - with hypovitaminosis B12).

The area of ​​the anus is examined in younger children in the position on the side, in the rest - in the knee-elbow position. On examination, the following are revealed: anal fissures, a decrease in the tone of the sphincter and its gaping with dysentery, prolapse of the rectum with persistent constipation or after an intestinal infection, irritation of the mucous membrane during pinworm invasion. A digital examination of the rectum and sigmoid colonoscopy can detect polyps, tumors, strictures, fecal stones, ulcers of the mucous membrane, etc.

Of great importance in assessing the state of the digestive system is a visual examination of the stool. In infants with intestinal enzyme dysfunction (simple dyspepsia), dyspeptic stools are often observed, which look like chopped eggs (liquid, greenish, mixed with white lumps and mucus, acid reaction). Very characteristic stool in colitis, dysentery. Bloody stool without admixture of feces against the background of an acutely developed severe general condition may be in children with intestinal intussusception. Discolored stool indicates a delay in the flow of bile into the intestine and is observed in children with hepatitis, blockage or atresia of the bile ducts. Along with determining the quantity, consistency, color, odor and pathological impurities visible to the eye, the characteristics of the stool are supplemented by microscopy (coprogram) data on the presence of leukocytes, erythrocytes, mucus in the feces, as well as helminth eggs, lamblia cysts. In addition, bacteriological and biochemical studies of feces are carried out.

Laboratory and instrumental research

These studies are similar to those conducted in adults. The most important is endoscopy, which is currently widely used, which allows visually assessing the condition of the mucous membranes of the stomach and intestines, making a targeted biopsy, detecting neoplasms, ulcers, erosions, congenital and acquired strictures, diverticula, etc. Endoscopic examinations of children of early and preschool age are carried out under general anesthesia. Ultrasound examination of parenchymal organs, radiography of the biliary tract and gastrointestinal tract (with barium), gastric and duodenal sounding, determination of enzymes, biochemical and immunological blood parameters, biochemical analysis of bile, rheohepatography, laparoscopy with targeted liver biopsy and subsequent morphological study of the biopsy are also used. .

Of particular importance are laboratory and instrumental research methods in the diagnosis of diseases of the pancreas, which, due to its location, is not amenable to direct methods of physical examination. The size and contours of the gland, the presence of stones in the excretory ducts, developmental anomalies are detected by relaxation duodenography, as well as retrograde pancreatocholangiography, echopancreatography. Violations of exocrine function observed in cystic fibrosis, post-traumatic cysts, biliary atresia, pancreatitis, are accompanied by a change in the level of the main enzymes that are determined in the blood serum (amylase, lipase, trypsin and its inhibitors), in saliva (isoamylase), urine and duodenal contents. An important indicator of insufficiency of exocrine pancreatic function is persistent steatorrhea. The intrasecretory activity of the pancreas can be judged on the basis of studying the nature of the glycemic curve.