SEMIOTICS OF LESIONS OF THE DIGESTIVE ORGANS

Diseases of the digestive system in children of preschool and school age amount to 79.3 cases per 1000 children. The proportion of functional disorders of the digestive system decreases with age in children, and at the same time the frequency of organic diseases increases. For the diagnosis of diseases of the digestive system, analysis of complaints, knowledge and consideration of the anatomical and physiological characteristics of the child’s gastrointestinal tract are important.

ANATOMICAL AND PHYSIOLOGICAL FEATURES OF THE GASTROINTESTINAL TRACT IN CHILDREN

The formation of the digestive organs begins from the 3-4th week of the embryonic period, when the primary gut is formed from the endodermal plate. At the anterior end, at the 4th week, a mouth opening appears, and a little later, an anal opening appears at the opposite end. The intestine quickly lengthens, and from the 5th week of the embryonic period, the intestinal tube is divided into two sections, which are the basis for the formation of the small and large intestines. During this period, the stomach begins to stand out - as an expansion of the primary intestine. At the same time, the formation of the mucous, muscular and serous membranes of the gastrointestinal tract occurs, in which blood and lymphatic vessels, nerve plexuses, and endocrine cells are formed.

In the first weeks of pregnancy, the endocrine apparatus of the gastrointestinal tract is formed in the fetus and the production of regulatory peptides begins. During intrauterine development, the number of endocrine cells increases, the content of regulatory peptides in them increases (gastrin, secretin, motilin, gastric inhibitory peptide (GIP), vasoactive intestinal peptide (VIP), enteroglyczagon, somatostatin, neurotensin, etc.). At the same time, the reactivity of target organs towards regulatory peptides increases. In prenatal period peripheral and central mechanisms of nervous regulation of the gastrointestinal tract are laid.

In the fetus, the gastrointestinal tract begins to function already at the 16-20th week of intrauterine life. By this time, the swallowing reflex is expressed, amylase is found in the salivary glands, pepsinogen in the gastric glands, and secretin in the small intestine. A normal fetus swallows a large amount of amniotic fluid, the individual components of which are hydrolyzed in the intestine and absorbed. The undigested part of the contents of the stomach and intestines goes to the formation of meconium.

During intrauterine development, before implantation of the embryo into the wall of the uterus, its nutrition occurs due to reserves in the cytoplasm of the egg. The embryo feeds on the secretions of the uterine mucosa and material yolk sac(histotrophic type of nutrition). Since the formation of the placenta, hemotrophic (transplacental) nutrition, provided by the transport of nutrients from the mother’s blood to the fetus through the placenta, becomes of primary importance. It plays a leading role before the birth of the child.

From 4-5 months of intrauterine development, the activity of the digestive organs begins and, together with hemotrophic nutrition, amniotrophic nutrition occurs. The daily amount of fluid absorbed by the fetus in the last months of pregnancy can reach more than 1 liter. The fetus absorbs amniotic fluid containing nutrients (proteins, amino acids, glucose, vitamins, hormones, salts, etc.) and enzymes that hydrolyze them. Some enzymes enter the amniotic fluid from the fetus with saliva and urine, the second source is the placenta, the third source is the mother's body (enzymes through the placenta and bypassing it can enter the amniotic fluid from the blood of a pregnant woman).

Some nutrients are absorbed from the gastrointestinal tract without preliminary hydrolysis (glucose, amino acids, some dimers, oligomers and even polymers), since the fetal intestinal tube has high permeability and fetal enterocytes are capable of pinocytosis. This is important to consider when organizing nutrition for a pregnant woman in order to prevent allergic diseases. Some of the nutrients in the amniotic fluid are digested by its own enzymes, that is, the autolytic type of digestion plays a large role in the amniotic nutrition of the fetus. Amniotrophic nutrition, such as its own cavity digestion, can be carried out from the 2nd half of pregnancy, when the cells of the stomach and pancreas of the fetus secrete pepsinogen and lipase, although their levels are low. Amniotrophic nutrition and the corresponding digestion are important not only for the supply of nutrients to the blood of the fetus, but also as a preparation of the digestive organs for lactotrophic nutrition.

In newborns and children in the first months of life, the oral cavity is relatively small, the tongue is large, the muscles of the mouth and cheeks are well developed, and in the thickness of the cheeks there are fatty bodies (Bishat's lumps), which are distinguished by significant elasticity due to the predominance of solid (saturated) fatty acids in them. These features ensure proper breastfeeding. The mucous membrane of the oral cavity is tender, dry, rich in blood vessels (easily vulnerable). The salivary glands are poorly developed and produce little saliva (the submandibular and sublingual glands function to a greater extent in infants, and in children after one year of age and adults - the parotid glands). The salivary glands begin to function actively by the 3-4th month of life, but even at the age of 1 year, the volume of saliva (150 ml) is 1/10 of the amount in an adult. The enzymatic activity of saliva at an early age is 1/3-1/2 of its activity in adults, but it reaches the level of adults within 1-2 years. Although the enzymatic activity of saliva at an early age is low, its effect on milk promotes its curdling in the stomach to form small flakes, which facilitates the hydrolysis of casein. Hypersalivation at 3-4 months of age is caused by teething; saliva may flow out of the mouth due to the inability of children to swallow it. The reaction of saliva in children of the first year of life is neutral or slightly acidic - this can contribute to the development of thrush of the oral mucosa if it is not properly cared for. At an early age, saliva has a low content of lysozyme, secretory immunoglobulin A, which makes it low bactericidal and requires compliance with proper care behind the oral cavity.

Esophagus in children early age has a funnel shape. Its length in newborns is 10 cm, with age it increases, and the diameter of the esophagus becomes larger. At the age of up to one year, physiological narrowing of the esophagus is weakly expressed, especially in the area of ​​the cardiac part of the stomach, which contributes to frequent regurgitation of food in children of the 1st year of life.

The stomach in infants is located horizontally, its bottom and cardiac region are poorly developed, which explains the tendency of children in the first year of life to regurgitate and vomit. As the child begins to walk, the axis of the stomach becomes more vertical, and by the age of 7-11 it is located in the same way as in an adult. The stomach capacity of a newborn is 30-35 ml, by the age of one year it increases to 250-300 ml, and by the age of 8 it reaches 1000 ml. The secretory apparatus of the stomach in children of the 1st year of life is not sufficiently developed; they have fewer glands in the gastric mucosa than adults, and their functional abilities are low. Although the composition of gastric juice in children is the same as in adults (hydrochloric acid, lactic acid, pepsin, rennet, lipase), the acidity and enzymatic activity are lower, which determines the low barrier function of the stomach and the pH of gastric juice (4-5, in adults 1.5-2.2). In this regard, proteins are not sufficiently broken down in the stomach by pepsin; they are broken down mainly by cathepsins and gastricsin, produced by the gastric mucosa; their optimal action is at pH 4-5. Gastric lipase (produced by the pyloric part of the stomach) breaks down in an acidic environment, together with human milk lipase, up to half of the fats in human milk. These features must be taken into account when prescribing various types nutrition for the child. With age, the secretory activity of the stomach increases. Gastric motility in children in the first months of life is slow, peristalsis is sluggish. The timing of food evacuation from the stomach depends on the nature of feeding. Women's milk lingers in the stomach for 2-3 hours, cow's milk - 3-4 hours, which indicates the difficulty of digesting the latter.

The intestines in children are relatively longer than in adults. The cecum is mobile due to the long mesentery, the appendix can therefore be located in the right iliac region, displaced into the small pelvis and into the left half of the abdomen, which creates difficulties in diagnosing appendicitis in young children. The sigmoid colon is relatively long, which predisposes children to constipation, especially if the mother's milk contains high amounts of fat. The rectum in children in the first months of life is also long, with weak fixation of the mucous and submucosal layer, and therefore, with tenesmus and persistent constipation, it may prolapse through the anus. The mesentery is longer and more easily stretchable, which can lead to torsion, intussusception, and other pathological processes. The occurrence of intussusception in young children is also facilitated by weakness of the ileocecal valve. A feature of the intestines in children is the better development of circular muscles than longitudinal ones, which predisposes to intestinal spasms and intestinal colic. A feature of the digestive organs in children is also the poor development of the lesser and greater omentum, and this leads to the fact that the infectious process in abdominal cavity(appendicitis, etc.) often leads to diffuse peritonitis.

By the time the child is born, the secretory apparatus of the intestine is generally formed; the intestinal juice contains the same enzymes as in adults (enterokinase, alkaline phosphatease, lipase, erypsin, amylase, maltase, lactase, nuclease, etc.), but their activity low. Under the influence of intestinal enzymes, mainly the pancreas, the breakdown of proteins, fats and carbohydrates occurs. However, the pH of duodenal juice in young children is slightly acidic or neutral, so the breakdown of protein by trypsin is limited (for trypsin, the optimal pH is alkaline). The process of fat digestion is especially intense due to the low activity of lipolytic enzymes. In children who are on breastfeeding, bile-emulsified lipids are broken down by 50% under the influence of mother's milk lipase. Digestion of carbohydrates occurs in the small intestine under the influence of pancreatic amylase and intestinal juice disaccharidases. Rotting processes in the intestines do not occur in healthy infants. 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 to toxins and microbes.

The motor function of the gastrointestinal tract in young children also has a number of features. The peristaltic wave of the esophagus and mechanical irritation of its lower section with a bolus of food cause a reflex opening of the entrance to the stomach. Gastric motility consists of peristalsis (rhythmic waves of contraction from the cardiac region to the pylorus), peristole (resistance exerted by the walls of the stomach to the stretching effect of food) and fluctuations in the tone of the stomach wall, which appears 2-3 hours after eating. Motility of the small intestine includes pendulum-like movement (rhythmic oscillations that mix intestinal contents with intestinal secretions and create favorable conditions for absorption), fluctuations in the tone of the intestinal wall and peristalsis (worm-like movements along the intestine, promoting the movement of food). Pendulum-like and peristaltic movements are also observed in the large intestine, and in the proximal sections - antiperistalsis, which promotes the formation of feces. The time it takes for food gruel to pass through the intestines in children is shorter than in adults: in newborns - from 4 to 18 hours, in older ones - about a day. It should be noted that when artificial feeding this period is extended. The act of defecation in infants occurs reflexively without the participation of a volitional moment, and only by the end of the first year of life does defecation become voluntary.

In the first hours and days of life, a newborn excretes original feces, or meconium, in the form of a thick, odorless, dark olive-colored mass. Subsequently, healthy bowel movements infant They have a yellow color, an acidic reaction and a sour smell, and their consistency is mushy. At an older age, the stool becomes formed. The frequency of stool in infants is from 1 to 4-5 times a day, in older children - 1 time a day.

In the first hours of life, a child’s intestines are almost free of bacteria. Subsequently, the gastrointestinal tract is populated by microflora. Staphylococci, streptococci, pneumococci, E. coli and some other bacteria can be found in the oral cavity of an infant. E. coli, bifidobacteria, lactic acid bacilli, etc. appear in the stool. With artificial and mixed feeding the bacterial infection phase occurs more quickly. Intestinal bacteria contribute to the enzymatic digestion of food. At natural feeding bifidobacteria and lactic acid bacilli predominate, and in smaller quantities - Escherichia coli. The feces are light yellow with a sour odor, ointment-like. With artificial and mixed feeding, due to the predominance of putrefaction processes in the feces, there is a lot of E. coli, fermentative flora (bifidoflora, lactic acid bacilli) is present in smaller quantities.

The liver in children is relatively large, in newborns it makes up about 4% of body weight (in adults - 2% of body weight). In young children, bile formation is less intense than in older children. The bile of children is poor in bile acids, cholesterol, lecithin, salts and alkali, but rich in water, mucin, pigments and urea, and also contains more taurocholic acid than glycocholic acid. It is important to note that taurocholic acid is an antiseptic. Bile neutralizes acidic food gruel, which makes the activity of pancreatic and intestinal secretions possible. In addition, bile activates pancreatic lipase, emulsifies fats, dissolves fatty acids, turning them into soaps, and enhances peristalsis of the large intestine.

Thus, the digestive system in children differs in a number of anatomical and physiological features that affect the functional ability of these organs. A child in the first year of life has a relatively greater need for food than older children. Although the child has all the necessary digestive enzymes, the functional capacity of the digestive organs is limited and can only be sufficient if the child receives physiological food, namely human milk. Even small deviations in the quantity and quality of food can cause digestive disorders in an infant (they are especially common in the 1st year of life) and ultimately lead to retarded physical development.

In children of the first year of life, the need for food is large, and the functional ability of digestion is limited. If we take into account both conditions, namely a large volume of food and insufficient secretory ability of the digestive glands, it will become clear what properties the food of children of the first year of life should have and why any violation in the diet of these children can easily cause digestive and nutritional disorders. This ability is sufficient only if the child receives physiological food. There is no doubt that for children in the first year of life, the most suitable, the only normal and natural food is mother's milk.

The intensity of digestive processes in infants is especially high. However, the secretory function of the digestive glands (salivary, glands of the stomach, pancreas and intestines) is significantly lower than in an adult, which is associated with the anatomical and physiological characteristics of their digestive organs.

The oral mucosa of a child is very delicate, rich in blood vessels, but in the first months of life it is rather dry. The salivary glands (parotid, sublingual, submandibular) begin to actively secrete saliva in the third or fourth month of life. In newborns, there is no amylase in the saliva. The reaction of saliva is initially neutral, then alkaline. Saliva contains the amylolytic enzyme ptyalin.

The tongue and chewing muscles of an infant play an important role in the act of sucking. This is also facilitated by transverse folding and well-developed muscles of the lips, accumulation of fat in the thickness of the cheeks (Bishat's lumps), and roller-like thickenings on the gums. A normal full-term baby has well-developed sucking and swallowing reflexes.

The esophagus is distinguished by the tenderness of the mucous membrane, insufficient expression of elastic tissue, the almost complete absence of glands and poor muscle development. The length of the esophagus of an infant is 10-12 cm, at 5 years old it is 16 cm.

The stomach, located in the newborn's left hypochondrium, occupies a horizontal position. Later, when the child begins to walk, the stomach takes on a more vertical position. In the first month of life, the stomach capacity is 30-35 ml, by 3 months it increases to 100 ml and by the year - to 250 ml. The fundus of the stomach is less developed, and the inlet sphincter is also underdeveloped, which is why infants often regurgitate. The mucous membrane is tender, rich in blood capillaries, poor in elastic tissue. The number of gastric glands and goblet cells is relatively less than in adults.

In children of the first year of life, the gastric juice contains the same chemical substances as in an adult: hydrochloric and lactic acid, table salt, enzymes (pepsin, which breaks down proteins into albumoses and peptones; rennet enzyme chymosin, which curdles milk; cathepsin, which is primary protease with optimal action at a pH of about 5-6; lipase, which breaks down fats). The acidic environment of gastric contents, caused by hydrochloric acid secreted by the parietal cells, is important factor, increasing the activity of enzymes that break down proteins and fats. In infants, little gastric juice is secreted and its acidity is low (pH 5.8-3.8). IN school age pH reaches 1.5-2 (as in adults). The strength of pepsin and labenzyme in children of the first year of life is approximately 10-15 times lower than in adults. The lipase content in gastric juice is low and increases with age, making it difficult to digest fat.

Classical studies by I.P. Pavlov showed the leading importance for the secretion of the gastric glands of conditioned and unconditioned reflex stimuli. Subsequently, many domestic physiologists and pediatricians proved that the separation of the so-called appetizing (“ignition”) juice into conditioned stimuli, established by I.P. Pavlov in the experiment, plays an important role in the digestion of children. I.P. Pavlov also discovered a pattern that the acidity and enzymatic activity of gastric juice are directly dependent on the composition of food.

In a healthy child, after feeding with breast milk, the stomach is empty after 2-2.5 hours, when feeding with cow's milk after 3-4 hours. During this time, under the influence of rennet and pepsin, the milk curdles, and partial breakdown of proteins occurs; Almost 50% of fat is broken down in the stomach under the influence of lipases breast milk. With artificial feeding, fat breakdown almost does not occur. Water and mineral salts are partially absorbed in the stomach. Protein and fatty food lingers longer.

The acidic gastric contents enter the duodenum in portions through the pylorus, which opens reflexively. Further digestion and absorption of nutrients occurs in the intestines. In an infant, the length of the intestine exceeds the length of the body by 6 times, in an adult - by 4 times. The intestinal mucosa is delicate, well vascularized and contains a large number of digestive glands and villi. The muscle layer is poorly developed, the mesentery is wider. The cecum is located high, covered with peritoneum and mobile. The sigmoid colon forms more loops. The rectum is relatively longer and weakly fixed.

In addition to gastric contents, pancreatic secretions and bile from the liver enter the cavity of the duodenum. The pancreas at birth is not sufficiently differentiated and has a large number of capillaries and vascular anastomoses. Its mass is growing rapidly. In a newborn, the weight of the pancreas is 2.5-3 g, at 3 months - about 6 g, by 5 years it reaches 30 g, in an adult - 90-120 g. Its secretion contains enzymes: trypsin, amylase, diastase and lipase. The pancreas releases insulin into the blood. Trypsin enters the intestine in the form of trypsinogen, which is activated by enterokinase and calcium salts. Trypsin breaks down proteins into amino acids. Amylase in the intestine is partially activated by bile and breaks down polysaccharides (starch and glycogen) into disaccharides, which are then acted upon by pancreatic and intestinal diastases, breaking them down into monosaccharides. Lipase breaks down emulsified neutral fats into glycerol and fatty acids. In the first months of life, relatively little bile is produced, and it contains less fatty acids.

Bile neutralizes acidic food gruel entering the duodenum from the stomach, emulsifies fats, activates pancreatic lipase, promotes the absorption of fatty acids and enhances intestinal motility.

The reaction of duodenal and intestinal juices in young children at the beginning of digestion is slightly acidic, and then, when more bile and pancreatic secretions are released into the intestines, it is neutral or even alkaline.

The intestinal glands of a child of the first year of life secrete almost all enzymes (erepsin, enterokinase, amylase, lactase, maltase, invertase). Erepsin, which breaks down albumoses, peptones and other polypeptides into amino acids, also acts on one of the main milk proteins - casein, promoting its greatest digestion throughout the small intestine. The enzymatic breakdown of food is to some extent supplemented by fermentation processes occurring in the large intestine. There is almost no rotting in the intestines of a healthy child in the first months of life.

In addition to digestion with the help of juices entering the intestinal cavity (cavitary), the existence of so-called contact, or parietal, digestion was established (A.M. Ugolev). Each cell of the intestinal epithelium has from 2 to 5 thousand protoplasmic outgrowths - microvilli, due to which the surface on which digestion and absorption occurs sharply increases. Many enzymes are tightly bound to the surface of the villi. The final stage of digestion and absorption occurs on the villi and in the pores between them.

In the child's small intestine, the end products of the breakdown of all basic nutrients - proteins, fats, carbohydrates and salts - are absorbed. A number of salts, including phosphorus and iron, are absorbed in the large intestine. Due to the abundance of capillaries in the mucous membrane and the high permeability of the intestinal epithelium, products of incomplete breakdown of food and microbial toxins can easily penetrate into the blood of an infant. Toxic substances and microbes penetrating from the intestine into the portal vein system are neutralized in the liver. However, in young children, the liver parenchyma is not sufficiently differentiated and with severe intoxication, circulatory disorders and degenerative changes easily occur in it. As a result, the barrier function of the liver is sharply reduced. Intestinal motility is more lively and the time of passage of food gruel in it is shorter than in adults (on average, depending on food, 12-16 hours). With artificial feeding, the duration of intestinal digestion is longer.

The formation of fecal matter occurs in the large intestine with the participation of microorganisms. The gastrointestinal tract is actively populated by microbes during the first 10-20 hours of extrauterine life. Soon after birth, streptococci, staphylococci, fungi and other microorganisms are found in the oral cavity. Some saprophytes are also found in the stomach. There are fewer microbes in the upper intestines, and these are mainly representatives of the fermentative flora. A large number of bacteria accumulate in the lower intestines, especially in the transverse colon and rectum. In a breastfed child in the first months of life, B.bifidus, B.lactis aerogenes, and B.acidophilus predominate in the stool. With the introduction of complementary foods, the number of B. coli increases significantly. With early artificial or mixed feeding in the stool in large quantities B. coli is found, as well as B. bifidus, B. acidophilus and enterococci.

A healthy baby who is breastfed has stool 2-4 times a day. The stool has a golden-yellow color, a sour odor, and a pasty consistency. Their reaction is sour. With artificial feeding, the frequency of stools is 1-2 times a day. The stool is light yellow in color and has a pasty consistency as it contains less acids and water. Their reaction is neutral. The stool of children older than one year is partially formed, with a putrid odor and a darker color. In acute digestive disorders, the frequency and nature of stool changes.

The digestive organs include the mouth, esophagus, stomach and intestines. The pancreas and liver take part in digestion. The digestive organs are formed in the first 4 weeks of the intrauterine period; by 8 weeks of pregnancy, all parts of the digestive organs are defined. Amniotic fluid The fetus begins to swallow by 16–20 weeks of pregnancy. Digestive processes occur in the intestines of the fetus, where an accumulation of original feces - meconium - is formed.

FEATURES OF THE ORAL CAVITY

The main function of the oral cavity in a child after birth is to ensure the act of sucking. These features are: small size of the oral cavity, large tongue, well-developed muscles of the lips and masticatory muscles, transverse folds on the mucous membrane of the lips, roller-like thickening of the gums, in the cheeks there are lumps of fat (Bishat lumps), which give the cheeks elasticity.

The salivary glands in children are underdeveloped after birth; Little saliva is produced in the first 3 months. The development of the salivary glands is completed by 3 months of life.

FEATURES OF THE ESOPHAGUS

The esophagus in young children has a spindle-shaped shape, it is narrow and short. In a newborn, its length is only 10 cm, in children at 1 year of age - 12 cm, at 10 years - 18 cm. Its width, respectively, is at 7 years - 8 mm, at 12 years - 15 mm.

There are no glands on the mucous membrane of the esophagus. It has thin walls, poor development of muscle and elastic tissue, and is well supplied with blood. The entrance to the esophagus is located high. He has no physiological restrictions.

FEATURES OF THE STOMACH

In infancy, the stomach is located horizontally. As the child grows and develops and begins to walk, the stomach gradually takes on a vertical position, and by the age of 7-10 it is positioned in the same way as in adults. The capacity of the stomach gradually increases: at birth it is 7 ml, at 10 days - 80 ml, per year - 250 ml, at 3 years - 400-500 ml, at 10 years - 1500 ml.

V = 30 ml + 30 ? n,

where n is age in months.

A feature of the stomach in children is the poor development of its fundus and cardiac sphincter against the background good development pyloric section. This contributes to frequent regurgitation in the baby, especially when air enters the stomach during sucking.

The mucous membrane of the stomach is relatively thick, against this background there is poor development of the gastric glands. As the child grows, the active glands of the gastric mucosa are formed and enlarged 25 times, as in adults. Due to these features, the secretory apparatus in children of the first year of life is not sufficiently developed. The composition of gastric juice in children is similar to that of adults, but its acid and enzymatic activity is much lower. The barrier activity of gastric juice is low.

The main active enzyme in gastric juice is rennet (labenzyme), which provides the first phase of digestion - milk curdling.

Very little lipase is secreted in the stomach of an infant. This deficiency is compensated by the presence of lipase in breast milk, as well as the baby’s pancreatic juice. If a child receives cow's milk, its fats are not broken down in the stomach.

Absorption in the stomach is insignificant and concerns substances such as salts, water, glucose, and protein breakdown products are only partially absorbed. The timing of food evacuation from the stomach depends on the type of feeding. Human milk is retained in the stomach for 2–3 hours.

FEATURES OF THE PANCREAS

The pancreas is small. In a newborn, its length is 5–6 cm, and by the age of 10 years it triples. The pancreas is located deep in the abdominal cavity at the level of the X thoracic vertebra; in older age, it is located at the level of the I lumbar vertebra. Its intensive growth occurs until the age of 14.

Dimensions of the pancreas in children in the first year of life (cm):

1) newborn – 6.0 ? 1.3? 0.5;

2) 5 months – 7.0 ? 1.5? 0.8;

3) 1 year – 9.5 ? 2.0? 1.0.

The pancreas is richly supplied with blood vessels. Its capsule is less dense than that of adults and consists of fine fibrous structures. Its excretory ducts are wide, which provides good drainage.

The child's pancreas has exocrine and intrasecretory functions. It produces pancreatic juice, consisting of albumins, globulins, trace elements and electrolytes, enzymes necessary for digesting food. The enzymes include proteolytic enzymes: trypsin, chymotrypsin, elastase, as well as lipolytic enzymes and amylolytic enzymes. Regulation of the pancreas is provided by secretin, which stimulates the separation of the liquid part of pancreatic juice, and pancreozymin, which enhances the secretion of enzymes along with other hormone-like substances that are produced by the mucous membrane of the duodenum and small intestine.

The intrasecretory function of the pancreas is performed through the synthesis of hormones responsible for the regulation of carbohydrate and fat metabolism.

LIVER

The newborn's liver is the largest organ, occupying 1/3 of the abdominal cavity. At 11 months its mass doubles, by 2–3 years it triples, by 8 years it increases 5 times, by 16–17 years the liver mass increases 10 times.

The liver performs the following functions:

1) produces bile, which is involved in intestinal digestion;

2) stimulates intestinal motility due to the action of bile;

3) deposits nutrients;

4) performs a barrier function;

5) participates in metabolism, including the transformation of vitamins A, D, C, B 12, K;

6) in the prenatal period it is a hematopoietic organ.

After birth, further formation of liver lobules occurs. The functional capabilities of the liver in young children are low: in newborns, the metabolism of indirect bilirubin is not complete.

FEATURES OF THE GALL BLADDER

The gallbladder is located under the right lobe of the liver and has a spindle-shaped shape, its length reaches 3 cm. It acquires a typical pear-shaped shape by 7 months, and by 2 years it reaches the edge of the liver.

The main function of the gallbladder is the accumulation and secretion of hepatic bile. The composition of a child's bile differs from that of an adult. It contains little bile acids, cholesterol, salts, a lot of water, mucin, and pigments. During the neonatal period, bile is rich in urea. In the bile of a child, glycocholic acid predominates and enhances the bactericidal effect of bile, and also accelerates the separation of pancreatic juice. Bile emulsifies fats, dissolves fatty acids, and improves peristalsis.

With age, the size of the gallbladder increases, and bile of a different composition begins to be secreted than in children. younger age. The length of the common bile duct increases with age.

Dimensions of the gallbladder in children (Chapova O.I., 2005):

1) newborn – 3.5? 1.0? 0.68 cm;

2) 1 year – 5.0 ? 1.6? 1.0 cm;

3) 5 years – 7.0 ? 1.8? 1.2 cm;

4) 12 years – 7.7 ? 3.7? 1.5 cm.

FEATURES OF THE SMALL INTESTINE

The intestines in children are relatively longer than in adults.

The ratio of the length of the small intestine to the length of the body in a newborn is 8.3: 1, in the first year of life – 7.6: 1, at 16 years – 6.6: 1.

The length of the small intestine in a child of the first year of life is 1.2–2.8 m. The area of ​​the internal surface of the small intestine in the first week of life is 85 cm2, in an adult – 3.3? 103 cm 2. The area of ​​the small intestine increases due to the development of epithelium and microvilli.

The small intestine is anatomically divided into 3 sections. The first section is the duodenum, the length of which in a newborn is 10 cm, in an adult it reaches 30 cm. It has three sphincters, the main function of which is to create the area low blood pressure where food comes into contact with pancreatic enzymes.

The second and third sections are represented by the small and ileal intestines. The length of the small intestine is 2/5 of the length to the ileocecal angle, the remaining 3/5 is the ileum.

Digestion of food and absorption of its ingredients occurs in the small intestine. The intestinal mucosa is rich in blood vessels, and the epithelium of the small intestine is rapidly renewed. Intestinal glands in children are larger, lymphoid tissue is scattered throughout the intestine. As the child grows, Peyer's patches form.

FEATURES OF THE LARGE INTESTINE

The large intestine is made up of different sections and develops after birth. In children under 4 years of age, the ascending colon is longer than the descending colon. The sigmoid colon is relatively longer. Gradually these features disappear. The cecum and appendix are mobile, the appendix is ​​often located atypically.

The rectum in children in the first months of life is relatively long. In newborns, the ampulla of the rectum is undeveloped, and the surrounding fatty tissue is poorly developed. By 2 years of age, the rectum assumes its final position, which contributes to early rectal prolapse. childhood with straining, with persistent constipation and tenesmus in weakened children.

The omentum in children under 5 years of age is short.

Juice secretion in the large intestine in children is small, but with mechanical irritation it increases sharply.

The large intestine absorbs water and forms feces.

FEATURES OF INTESTINAL MICROFLORA

The fetal gastrointestinal tract is sterile. When a child comes into contact with the environment, it becomes colonized with microflora. The microflora in the stomach and duodenum is poor. In the small and large intestines, the number of microbes increases and depends on the type of feeding. The main microflora is B. bifidum, the growth of which is stimulated by β-lactose in breast milk. During artificial feeding, opportunistic gram-negative Escherichia coli dominates in the intestines. Normal intestinal flora has two main functions:

1) creation of an immunological barrier;

2) synthesis of vitamins and enzymes.

FEATURES OF DIGESTION IN EARLY CHILDREN

For children in the first months of life, the nutrients that come with mother’s milk and are digested by substances contained in human milk itself are of decisive importance. With the introduction of complementary foods, the mechanisms of the child's enzyme systems are stimulated. The absorption of food ingredients in young children has its own characteristics. Casein first curdles in the stomach under the influence of rennet. In the small intestine, it begins to break down into amino acids, which are activated and absorbed.

Digestion of fat depends on the type of feeding. Cow's milk fats contain long-chain fats that are broken down by pancreatic lipase in the presence of fatty acids.

Absorption of fat occurs in the final and middle parts of the small intestine. The breakdown of milk sugar in children occurs in the rim of the intestinal epithelium. Human milk contains β-lactose, while cow's milk contains β-lactose. In this regard, during artificial feeding, the carbohydrate composition of food is changed. Vitamins are also absorbed in the small intestine.

ANATOMIC-PHYSIOLOGICAL
FEATURES OF THE GASTROINTESTINAL TRACT
IN CHILDREN

The digestive system represents
is a complex digestive system
conveyor, from the coordinated work of which
depends largely on the condition
child and his health
Age-related changes buildings
digestive system and its
functions are inextricably linked with
features of life
organism at each stage
ontogenesis, with energy and
plastic needs.with
nutritional habits

Functions of the digestive system

Digestion and absorption of nutrients
Motor and transport-evacuation
Secretory and excretory, regulating
homeostasis of the enteral environment and the whole organism
Endogenous digestion and utilization
endogenous substances due to hydrolysis and
absorption of endogenous substrates and metabolites
Metabolic (transformation and biosynthesis
substances from endogenous and exogenous substrates)
Protective (epithelial and mucous
barriers, immune system, etc.)
Regulatory, carried out using
substrate, nervous and endocrine
regulation

7-8 days - formation of a closed tube (primary intestine) from the endoderm; 12 days - division of the primary intestine into the intraembryonic part (digestion

Embryogenesis of the digestive
tract
7-8 days formation of a closed tube (primary
intestines) from endoderm
Day 12: division of the primary intestine into
intraembryonic part (digestive tract) and
extraembryonic (yolk sac)
3 weeks –
melting of the oropharyngeal membrane
4 weeks –
formation of various departments
foregut - pharynx, esophagus, stomach, part of the duodenum
intestines, liver, pancreas
midgut - part of the duodenum, jejunum and ileum
hindgut - all parts of the large intestine
3 months-
expansion of the cloacal membrane

Oral cavity

Features of the oral cavity in children

In newborns, the oral cavity is relatively
small
Alveolar processes are poorly expressed
Weakly pronounced vault of the hard palate
The tongue is relatively large
Well developed chewing muscles
There are Bisha lumps in the thickness of the cheeks
The epithelium is tender and somewhat
dryness, tendency to candidiasis (pH neutral)
The mucosa is bright, abundantly vascularized
Along the midline on the hard palate are visible
white-yellow dots, so-called Bon's nodules
A dense tissue stretches along the jaw processes
roller (Robin-Magiteau fold)
The visible part of the mucous membrane of the lips has
cross striations (ridges
Pfaundler-Lushka)

Oral cavity of a newborn

Features of salivation in children

Salivary glands of a newborn morphologically
formed
In the first 3 months, saliva secretion is low,
role - ensuring the tightness of the oral cavity
By 4-5 months there appears abundant
salivation caused by insufficient
maturity of central regulatory mechanisms
salivation and swallowing
Amylase activity is low, peaking at age 27
Saliva pH in children is 7.32, in adults - 6.4
In children on artificial feeding and after
introduction of complementary foods main functions of salivadigestion of carbohydrates and formation of food
lump
Newborn saliva is also powerful
cytoprotection factor and contains components
nonspecific protection
(lysozyme, prostaglandins, lactic acid, etc.)

Esophagus
Segments
esophagus
1-tracheal, 2-aortic, 3-interaortic, 4-bronchial, 5-subbronchial, 6-retropericardial, 7-supraphrenic, 8-phrenic, 9-abdominal

FEATURES OF THE ESOPHAGUS IN CHILDREN

The lumen of the esophagus is formed from 3-4 months
intrauterine life
The entrance to the esophagus in a newborn is located on
disc level between the third and fourth
cervical vertebrae and gradually with age
is decreasing
Anatomical narrowing of the esophagus in children
the first year are weakly expressed
The diameter of a newborn's esophagus is 5
mm., at 6 months - 8-10 mm., at 1 year - 12 mm., at 15 years - 1819 mm.
Transition of the esophagus into the stomach in all periods
childhood is located at the level of the tenth and eleventh thoracic vertebrae

The structure of the adult stomach

Stomach of a newborn

Features of the stomach in children

Physiological volume of the stomach
newborn - 7 ml., on the 4th day - 40-50 ml., on
10 days - 80 ml., 1 year - 250 ml., 3 years - 400600 ml., 10 years - 1500 ml.
The newborn has a poorly developed fundus and
cardiac section of the stomach, final
the formation of which occurs by 8 years
The inlet of the stomach is located above
diaphragm and is located in the chest cavity
The newborn has a well-developed pyloric
stomach section
The newborn's stomach is located in an oblique position
frontal plane, its bottom is in position
lying down is below the anthro-pyloric
department

The gastric mucosa is relatively thicker
Gastric glands of the newborn
functionally and morphologically not
developed, the number of glands per 1 kg. body weight 2.5
times less than that of an adult
Gastric secretion in a newborn is low,
intragastric pH not lower than 4. By 1 year pH
decreases to 1.5-2.
Neurohumoral regulation of gastric
secretion begins from 1 month of life, up to two
months the source of hydrogen ions is
lactic acid and only later hydrochloric acid
The predominant proteolytic enzyme is
action of renin (chymosin) and gastricsin
High gastric activity
lipases that hydrolyze fats in neutral
environment without the presence of bile acids. In the stomach
A third of the fats in human milk are hydrolyzed.

Histological picture of the normal mucous membrane of the child’s stomach

Pancreas

Pancreatic secretion
Proteinases (trypsinogen, chymotrypsinogen
A, B and C, carboxypeptidases A and B, proelastase
and phospholipase A zymogen.
Lipase
Amylase
Mucin
Bicarbonates providing pH = 6.8-8

Features of the pancreas in children

In newborns and children in the first months of life
insufficient differentiation of the gland
There is abundant vascularization, little
connective tissue
Weight of the gland at birth is 3 g, the most
intensive development and growth from 6 months. up to 2 years.5-10
years - weight 30-35g, 15 years - 50g.
Proteolytic activity in a newborn
high, increases to a maximum by 4-6 years
Lipolytic activity increases by 1 year and
remains high up to 9 years
Amylolytic activity from birth to 1 year
increases 4 times, maximum at 6-9 years
Enzyme activity is adaptive
character; when feeding them naturally
the concentration is low, when mixed it increases in
1.5-2 times, with artificial - 4-5 times.

Liver

Features of the liver and biliary tract in children

The newborn's liver occupies from one third to
half the volume of the abdominal cavity, its mass
makes up 4.38% of body weight
The left lobe of the liver is very massive at birth, by 18
months its relative size decreases
The growth rate of the child’s liver lags behind body weight: k
At 16 years of age, the weight of the liver increases 10 times, the weight of
20 times
In children under 5-7 years of age, the edge of the liver is normally palpated from
under the costal arch, and up to 2-3 years - by 2-3 cm.
The liver lobules are not clearly demarcated, the final
their differentiation ends by 1 month. life
Fibrous capsule of the liver in newborns
thin, there are delicate collagen and thin
elastic fibers
The liver of a newborn contains more
water, less protein, fat and glycogen, at the same time in
during the first three months, “glycogen capacity” is increased

LIVER FUNCTIONS
1. Biosynthesis of substances that function and
used in other organs:
- blood plasma proteins
- glucose
- fats
- ketone bodies, etc.
2. Biosynthesis of urea as the final product
nitrogen metabolism in the body
3. Digestive function associated with synthesis
acids, formation and secretion of bile
4. Neutralization of toxic substances,
formed in the body and coming from outside
5. Release of some metabolic products from
bile into the intestines (excess cholesterol, foods
breakdown of heme - bile pigments, etc.
metabolites resulting from
detoxification of substances in the liver

The gallbladder is hidden in a newborn
liver
Its length at the age of 2-7 years is no more than 2.5-4 cm.
8-12 years-5cm
13-15 years-7cm.
Maximum width is 3 cm.
Newborn children are predisposed
to cholestasis due to:
immaturity of liver enzymatic systems
decreased transport of bile acids
insufficient synthesis of bile acids
dominance of cholestatic fractions
bile acids (taurocholic acid)

Conjugation jaundice of newborns
(physiological)
-
physiological hemolysis
insufficient glucuronyl transferase activity
low activity and lack of synthesis
transport protein in newborns
- develops on the 2nd day
- max for 4-5 days
- disappears by 7-10 days
- in premature infants - up to 4 weeks
Jaundice in newborns with bilirubin levels
> 68.4 - 85.5 µmol/l
in children over 1 year of age > 20.5 - 34.2 µmol/l
Bilirubin encephalopathy in prematurity
with bilirubin level > 205 µmol/l

Small intestine

The child is 1 year old
length of small intestine 2
times less than
adult(1.2-2.8m.)
Per 1 kg of body weight
newborn
accounts for 1 m. of guts,
adult - 10 cm.
Surface area
small intestine
newborns-85cm².,y
adults-3.3·10³cm²
Surface area
small intestine
increases due to
circular
folds, lint and
microvilli.

Intestines

In the third month of intrauterine development
intestinal rotation occurs
Degree of yolk sac reduction
different (Meckel's diverticulum)
At birth, the length of the intestine is relatively greater than
in older children and adults

Circular folds in a newborn are pronounced
only in the initial part of the ileum
The length of his duodenum is 7.5-10 cm,
adult - 24-30 cm.
Intestinal loops lie more compactly
Children under 1 year of age experience weakness
ileocecal valve
Young children have a longer mesentery
The mucous membrane is thin and abundant
vascularized, highly permeable
Epithelial cells are rapidly renewed
The intestinal glands are larger than those of
adults, lymphoid tissue is scattered throughout
intestine, later grouped in the ileum
gut

Food conveyor stages

The main part of digestion in a young child is
parietal, membrane digestion carried out by one’s own
enzymes of enterocytes and enzymes
pancreatic, salivary, gastric epithelium, absorbed
different layers of glycocalyx
The activity of intestinal enzymes in a child is high
Better intracellular digestion

Own enzymes of the small intestinal mucosa

Glycosidases: Maltase-glucoamylase
Sucrase-isomaltase
Lactase-phlorisin hydrolase
Trehalase
Peptidases Aminopeptidase A
Aminopeptidase N
Aminopeptidase W
Carboxypeptidase P
Dipeptidyl aminopeptidase IV
Peptidyl dipeptidase
Pteroyl polyglutamate hydrolase
Enteropeptidase
Enteropeptidase 24.11
Endopeptidase-2
γ-glutamyl transferase
Phosphatases Alkaline phosphatase
Phosphodiesterase 1
unknown function 140 kDa – glycoprotein
Guanylate cyclase regulators
Phospholipase A

Absorption of nutrients in the small intestine

In the first days, weeks and
months of a child's life
all parts of the small intestine
have high
hydrolytic and
absorption
activity and only
later formed
predominance
proximal sections
in absorption
nutrients

Colon

Colon development is not complete at birth
Ribbons are barely noticeable, haustra are absent for up to 6 months
Up to 4 years of age, the ascending colon is longer than the descending colon
The mesentery is mobile, only in 2% of newborns it is fixed
The sigmoid colon is longer, more mobile and located higher

Features of the rectum in children

In young children
rectum is long, with
filling may take
pelvis
Final position
the rectum occupies 2
years
The ampoule of the rectum is not
developed
Anal columns and
sinuses are not formed
Fat fiber is not
developed, intestines poorly
fixed
Submucosal layer is good
developed
The muscle layer is poorly developed

Functions of the colon in children

Motor function in children
early age is unstable
Evacuation tank
reduced (young children
do not control the act of defecation)
Water resorption
Digestive (normal
microflora takes part
in digestion, fermentation
lactose)
Other intestinal functions
microflora (immunological,
protective, trophic, synthesis
vitamins, participation in circulation
bile acids, inactivation
physiologically active
substances and enzymes.

Composition of intestinal microflora in children

Composition of gastrointestinal microflora in children

Gastrointestinal motility in children

Normal stool frequency in children is:
the first months of life - up to 7 times a day
first years of life - 2-3 times a day
preschoolers - 1-2 times a day
schoolchildren - the interval between bowel movements is 32-48 hours
CONSTIPATION (constipation) - violation of spontaneous bowel movement
- slow, difficult, insufficient
Rome II criteria 1998 Constipation - 2 signs and > out of 4
severe straining during defecation
- feeling of incomplete bowel movement
- passage of hard and dry stool
- number of bowel movements less than 3 per week
DIARRHEA - frequent bowel movements
with increased water content in stool
In young children, diarrhea:
- stool volume > 15 g/kg per day
3 years and older:
- stool volume > 200 g per day
- frequency > 2 times a day
Diarrhea with polyfecal matter:
- stool volume > 2% of food eaten and liquid drunk

Main components of the gastrointestinal immune system

Some General Features of the Digestive System
Great variety of individual
morphofunctional variants of structure and
organizing the work of individual elements of the system
There is excess capacity of many elements (in
at the height of digestion, no more than a third is involved
total pool of enterocyte enzymes)
Regulatory mechanisms are presented and repeatedly
duplicated at the level
nervous, hormonal, substrate regulation and
capable of working autonomously
There is a morphofunctional dependence
various elements of the system, which creates a reserve
durability and provides adaptation when switching off
certain departments
The system operates continuously and has
circadian rhythmic activity
The normal functioning of the digestive tract depends
from sufficient supply of nutrients from
blood, as well as substrates from the enteral environment

The child's digestive system is in development and in general
characterized by:
relatively large compared to adult sizes
individual segments of the digestive tube in relation to
body surface
richness of vascularization of the mucous membrane, increased its
permeability, high rates of regeneration
insufficient development of muscle and elastic tissue
less pronounced connection between the own layer of the mucous membrane and
submucosal layer, insufficiency of intestinal fixation
elements (muscular-ligamentous structures)
Significant reduction in gastric digestion and activity
enzymes of cavity digestion, maximum displacement
the level of secretion of the digestive glands in the direction
distal gastrointestinal tract
good adaptation of secretory structures to the composition of food
partial hydrolysis of proteins, fats and carbohydrates due to
human milk enzymes
significant specific gravity of intracellular digestion
predominance of vagal influences on intestinal motor function
immaturity of local defense systems, both specific and
nonspecific

The oral cavity in newborns and young children is relatively small. The chewing muscles are well developed, the tongue is relatively large sizes, short and wide. The mucous membrane of the oral cavity is delicate, rich in blood vessels, and brightly colored. In the mouth of a young child there are some features that promote the act of sucking. These features are as follows:

1. in the thickness of the cheeks there are well-defined fatty lumps, the so-called Bisha’s pads, which help create negative pressure in the oral cavity during the act of sucking;

2. along the alveolar processes there is a ridge-like thickening, best expressed between the areas where canines will erupt in the future;

3. there are transverse folds on the mucous membrane of the lips. The presence of thickenings and transverse folds contributes to better coverage of the nipple during sucking.

The salivary glands in a newborn and a child in the first 3-4 months of life are not sufficiently differentiated. Therefore, little saliva is secreted, which causes dryness of the oral mucosa.

The esophagus in young children is relatively longer than in adults and has a funnel shape. Its mucous membrane is tender, rich in blood vessels, and dry due to the fact that mucous glands are almost absent. Its length in a newborn is 10-11 cm, in infants - 12 cm, in children 5 years old - 16 cm.

The stomach is located in the left hypochondrium and its only outlet - the pylorus - is near the midline. Until 1 year of age, the position of the stomach is horizontal; after 1 year, when the child begins to walk, the stomach takes on a more vertical position. The mucous membrane of the stomach is relatively thicker than in an adult. The muscles of the stomach are moderately developed, with the exception of the pylorus, where it is well developed. The sphincter of the inlet of the stomach is underdeveloped. This circumstance, with weak stomach muscles, contributes to frequent regurgitation in infancy.

The stomach capacity of a full-term newborn is 30-35 ml, at the age of 3 months - 100 ml, at 1 year - 250 ml. Secretory glands secrete gastric juice containing all the enzymes as in an adult, but with less activity.

The intestines of a child are relatively longer than those of an adult. The intestinal mucosa is highly developed, abundantly supplied with blood vessels, rich in cellular elements, tender, with big amount lymph nodes and villi. At the same time, the submucosal tissue, muscles, transverse folds are poorly developed and the nerve plexuses are structurally imperfect. All this taken together causes slight vulnerability of the gastrointestinal tract.

The intestines are sterile immediately after birth, but after a few hours they are already populated by various microbes coming from the air, from the mother’s nipples, and from care items.

Various parts of the digestive tract of a healthy child contain their characteristic microflora. The microflora of a child’s intestines is determined by the nature of feeding. The main intestinal microbe of breastfed children is bifidobacteria. Along with them, enterococci and E. coli are found in small quantities.

The duration of passage of food through the intestines varies widely: in newborns from 4 to 18 hours, in older ones - on average about 100 hours. The duration of intestinal digestion during artificial feeding is about 2 days.