Anatomical and physiological features of the digestive system in young children. Anatomical and physiological features of the gastrointestinal tract in children Anatomical physiological features of the newborn gastrointestinal tract

In children of the first year of life, the need for food is large, and the functional ability of digestion is limited. If both conditions are taken into account, namely, a large amount of food and an insufficient secretory capacity of the digestive glands, it becomes clear what properties the food of children of the first year of life should have and why any disturbance 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 of the first year of life, the most suitable, the only normal and natural food is mother's milk.

Particularly high intensity of the processes of digestion in infants. However, the secretory function of the digestive glands (salivary glands, stomach glands, 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 dry in the first months of life. The salivary glands (parotid, sublingual, submandibular) begin to actively secrete saliva in the third or fourth month of life. In newborns, amylase is absent in saliva. The reaction of saliva is initially neutral, then alkaline. Saliva contains the amylolytic enzyme ptyalin.

The tongue and chewing muscles in an infant play an important role in the act of sucking. This is also facilitated by transverse folding and well-developed musculature of the lips, the accumulation of fat in the thickness of the cheeks (Bish'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 in the left hypochondrium, occupies a horizontal position. Later, when the child begins to walk, the stomach assumes a more upright position. In the first month of life, the capacity of the stomach is 30-35 ml, by 3 months it increases to 100 ml and by the year - up to 250 ml. The bottom of the stomach is less developed, the sphincter of the inlet is also underdeveloped, and therefore infants often regurgitate. The mucosa 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 chemicals as in an adult: hydrochloric and lactic acid, salt, enzymes (pepsin, which breaks down proteins to albumose and peptones; the rennet enzyme chymosin, which curdles milk; cathepsin, which is primary protease with an optimum of action at a pH of about 5-6; a lipase that breaks down fats). The acidic environment of gastric contents, due to hydrochloric acid secreted by parietal cells, is an important factor that increases 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). At school age, the 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 an adult. The content of lipase in gastric juice is small and increases with age, which makes it difficult to digest fat.

The classical studies of IP 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 to conditioned stimuli, established by I.P. Pavlov in the experiment, plays an important role in the digestion of children. I.P. Pavlov also discovered the 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 released after 2-2.5 hours, while feeding with cow milk after 3-4 hours. During this time, under the influence of rennet and pepsin, milk curdles, and partial breakdown of proteins occurs; under the influence of lipases in the stomach, almost 50% of the fat of breast milk is broken down. With artificial feeding, the breakdown of fat almost does not occur. Water and mineral salts are partially absorbed in the stomach. Protein and fatty foods linger longer.

Acidic gastric contents through the pylorus, which opens reflexively, in portions enters the duodenum. Further digestion and absorption of nutrients takes place in the intestine. 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 muscular layer is poorly developed, the mesentery is wider. The caecum 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, the secret of the pancreas 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 the age of 5 it reaches 30 g, in an adult - 90-120 g. Its secret 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) to disaccharides, which are then acted upon by pancreatic and intestinal diastases, which break them down to monosaccharides. Lipase breaks down emulsified neutral fats into glycerol and fatty acids. In the first months of life, bile is produced relatively little, and it contains less fatty acids.

Bile neutralizes the acidic food gruel that enters 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, 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 to amino acids, also acts on one of the main milk proteins - casein, contributing to its greatest digestion throughout the entire small intestine. Enzymatic breakdown of food is to some extent supplemented by fermentation processes occurring in the large intestine. Rotting in the intestines of a healthy child in the first months of life is almost absent.

In addition to digestion with the help of juices entering the intestinal cavity (cavitary), the existence of the 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 increases dramatically. Many enzymes are strongly associated with the surface of the villi. On the villi and in the pores between them, the final stage of digestion and absorption takes place.

In the small intestine of the child, the end products of the breakdown of all the main 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 mucosa and the high permeability of the intestinal epithelium, in an infant, products of incomplete digestion of food and microbial toxins can easily penetrate into the bloodstream. Toxic substances and microbes that penetrate 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 slurry in it is shorter than in adults (on average, depending on the food, 12-16 hours). With artificial feeding, the duration of intestinal digestion is longer.

The formation of fecal masses occurs in the large intestine with the participation of microorganisms. The gastrointestinal tract is actively colonized by microbes during the first 10-20 hours of extrauterine life. Shortly 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 child of the first months of life, who is breastfed, B. bifidus, B. lactis aerogenes, 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, B. coli, as well as B. bifidus, B. acidophilus and enterococci are found in large numbers in the stool.

In a healthy child who is breastfed, the chair is 2-4 times a day. The stools at the same time have a golden-yellow color, sour smell, ointment-like consistency. Their reaction is sour. With artificial feeding, the frequency of stool is 1-2 times a day. The stools are light yellow in color, pasty in consistency, as they contain less acids and water. Their reaction is neutral. The stool of children older than a year is partially formed, with a putrid odor and a darker color. In acute digestive disorders, the frequency and nature of the stools change.

Importance of digestion.

Metabolism is a complex complex of various interdependent and interdependent processes that occur in the body from the moment these substances enter it and until the moment they are released. Metabolism is a necessary condition for life. It is one of its mandatory manifestations. For the normal functioning of the body, it is necessary to supply organic food material, mineral salts, water and oxygen from the external environment. For a period equal to the average life expectancy of a person, he consumes 1.3 tons of fat, 2.5 tons of proteins, 12.5 tons of carbohydrates and 75 tons of water. Metabolism consists of the processes of substances entering the body, their changes in the digestive tract, absorption, transformations inside cells and excretion of their decay products. The processes associated with the transformation of substances inside cells are called intracellular or intermediate metabolism. As a result of intracellular metabolism, hormones, enzymes and a wide variety of compounds are synthesized, which are used as a structural material for building cells and intercellular substance, which ensures the renewal and growth of a developing organism. The processes that result in the formation of living matter are called anabolism or assimilation. The other side of the metabolism is that the substances that form the living structure undergo splitting. This process of destruction of living matter is called catabolism or dissimilation. The processes of assimilation and dissimilation are very closely related, although they are opposite in their final results. Thus, it is known that the breakdown products of various substances contribute to their enhanced synthesis. Oxidation of cleavage products serves as a source of energy that the body constantly spends even in a state of complete rest. In this case, the same substances that are used for the synthesis of larger molecules can undergo oxidation. For example, in the liver, glycogen is synthesized from a part of the breakdown products of carbohydrates, and the energy for this synthesis is provided by another part of them, which is included in metabolic or metabolic processes. The processes of assimilation and dissimilation occur with the obligatory participation of enzymes.

The role of vitamins in nutrition

Vitamins were discovered at the turn of the 19th and 20th centuries as a result of studies of the role of various nutrients in the life of the body. The founder of vitaminology can be considered the Russian scientist N.I. Lunin, who in 1880 was the first to prove that in addition to proteins, fats, carbohydrates, water and minerals, some other substances are needed, without which the body cannot exist. These substances were called vitamins (vita + amin - "amines of life" from Latin), since the first vitamins isolated in their pure form contained an amino group in their composition. And although later it turned out that not all vitamin substances contain an amino group and nitrogen in general, the term "vitamin" has taken root in science.

According to the classical definition, vitamins are low molecular weight organic substances necessary for normal life that are not synthesized by an organism of a given species or are synthesized in an amount insufficient to ensure the life of the organism.

Vitamins are necessary for the normal course of almost all biochemical processes in our body. They provide the functions of the endocrine glands, that is, the production of hormones, increase mental and physical performance, support the body's resistance to the effects of adverse environmental factors (heat, cold, infections, and many others).

All vitamin substances are conditionally divided into vitamins proper and vitamin-like compounds, which are similar in their biological properties to vitamins, but are usually required in larger quantities. In addition, deficiency of vitamin-like substances is extremely rare, since their content in everyday food is such that even in the case of a very unbalanced diet, a person receives almost all of them in sufficient quantities.

According to their physical and chemical properties, vitamins are divided into two groups: fat-soluble and water-soluble. Each of the vitamins has a letter designation and a chemical name. In total, 12 true vitamins and 11 vitamin-like compounds are currently known.

At present, vitamins can be characterized as low-molecular organic compounds, which, being a necessary component of food, are present in it in extremely small quantities compared to its main components.

Vitamins are a necessary element of food for humans and a number of living organisms because they are not synthesized or some of them are synthesized in insufficient quantities by this organism. Vitamins are substances that ensure the normal course of biochemical and physiological processes in the body. They can be attributed to the group of biologically active compounds that have an effect on the metabolism in negligible concentrations.

Diseases of the gastrointestinal tract in children

Recently, there has been a significant increase in the number of diseases of the digestive system in children. Many factors contribute to this:

1. bad ecology,

2. unbalanced diet,

3. heredity.

Sweets and confectionery products with a high content of preservatives and artificial colors, fast food, carbonated drinks, so beloved by many, cause great harm to the child's body. The role of allergic reactions, neuropsychic factors, and neuroses is growing. Doctors note that intestinal diseases in children have two age peaks: at 5-6 years and at 9-11 years. The main pathological conditions are:

Constipation, diarrhea

Chronic and acute gastritis and gastroenteritis

Chronic duodenitis

Chronic enterocolitis

Peptic ulcer of the stomach and duodenum

· Chronic cholecystitis

· Chronic pancreatitis

Diseases of the biliary tract

Chronic and acute hepatitis

Of great importance in the occurrence and development of gastrointestinal diseases is the insufficient ability of the child's body to resist infections, since the child's immunity is still weak. The formation of immunity is greatly influenced by proper feeding in the first months of life.

The best option is breast milk, with which protective bodies are passed from mother to child, increasing the ability to resist various infections. Formula-fed babies are more susceptible to various diseases and have a weakened immune system. The cause of violations in the digestive system can be irregular feeding or overfeeding of the child, early introduction of complementary foods, non-compliance with hygiene standards.

A separate group consists of acute intestinal diseases in children (dysentery, salmonellosis). Their main clinical manifestations are dyspeptic disorders, dehydration (dehydration) of the body and symptoms of intoxication. Such manifestations are very dangerous and require immediate hospitalization of a sick child.

Intestinal infections are especially often diagnosed in childhood, this is due to the imperfection of protective mechanisms, the physiological characteristics of the digestive organs and the lack of sanitary and hygienic skills in children. Especially negative acute intestinal infections affect young children and can lead to a significant decrease in immunity, delayed physical development, and complications.

Their onset is accompanied by characteristic signs: a sharp increase in temperature, abdominal pain, diarrhea, vomiting, loss of appetite. The child becomes restless, or, on the contrary, lethargic and inhibited. The clinical picture largely depends on which parts of the intestine are affected. In any case, the child needs emergency medical care and antibiotic therapy.

The treatment of diseases of the digestive system in babies is handled by a pediatric gastroenterologist, it is he who should be contacted when unfavorable symptoms appear.

Age features of the digestive system in children and adolescents.

The most significant morphological and functional differences between the digestive organs of an adult and a child are observed only in the first years of postnatal development. The functional activity of the salivary glands is manifested with the appearance of milk teeth (from 5-6 months). A particularly significant increase in salivation occurs at the end of the first year of life. During the first two years, the formation of milk teeth is intensively going on. At the age of 2-2.5 years, the child already has 20 teeth and can eat relatively coarse food that requires chewing. In subsequent years, starting from the age of 5-6, milk teeth are gradually replaced by permanent ones. In the first years of postnatal development, the formation of other digestive organs is intensively going on: the esophagus, stomach, small and large intestines, liver and pancreas. Their size, shape and functional activity change. Thus, the volume of the stomach from birth to 1 year increases 10 times. The shape of the stomach in a newborn is round, after 1.5 years the stomach becomes pear-shaped, and from 6-7 years old its shape is no different from the stomach of adults. The structure of the muscular layer and the mucous membrane of the stomach changes significantly. In young children, there is a weak development of muscles and elastic elements of the stomach. The gastric glands in the first years of a child's life are still underdeveloped and few in number, although they are able to secrete gastric juice, in which the content of hydrochloric acid, the number and functional activity of enzymes are much lower than in an adult. So, the number of enzymes that break down proteins increases from 1.5 to 3 years, then at 5-6 years and at school age up to 12-14 years. The content of hydrochloric acid increases up to 15-16 years. A low concentration of hydrochloric acid causes weak bactericidal properties of gastric juice in children under 6-7 years of age, which contributes to an easier susceptibility of children of this age to gastrointestinal infections. In the process of development of children and adolescents, the activity of the enzymes contained in it also changes significantly. The activity of the enzyme chymosin, which acts on milk proteins, changes especially significantly in the first year of life. In a child of 1-2 months, its activity in conventional units is 16-32, and in 1 year it can reach 500 units, in adults this enzyme completely loses its significance in digestion. With age, the activity of other enzymes of gastric juice also increases, and at senior school age it reaches the level of an adult organism. It should be noted that in children under 10 years of age, absorption processes are actively going on in the stomach, while in adults these processes are carried out mainly only in the small intestine. The pancreas develops most intensively up to 1 year and at 5-6 years. According to its morphological and functional parameters, it reaches the level of an adult organism by the end of adolescence (at the age of 11-13, its morphological development is completed, and at 15-16 years - functional). Similar rates of morphofunctional development are observed in the liver and all parts of the intestine. Thus, the development of the digestive organs goes in parallel with the general physical development of children and adolescents. The most intensive growth and functional development of the digestive organs is observed in the 1st year of postnatal life, in preschool age and in adolescence, when the digestive organs in their morphological and functional properties approach the level of an adult organism. In addition, in the course of life, children and adolescents easily develop conditioned food reflexes, in particular, reflexes at the time of eating. In this regard, it is important to accustom children to strict adherence to the diet. Important for normal digestion is the observance of "food aesthetics".

43. Age features of the structure of the digestive organs in children.

The development of the digestive organs in children occurs in parallel with the development of the whole organism. And this development is divided into periods of the first year of life, preschool age and adolescence. At this time, the work of the digestive organs is controlled by the nervous system and depends on the state of the cerebral cortex. In the process of the formation of the digestive system in children, reflexes are easily developed for the time of eating, its composition and quantity. The esophagus in young children has the shape of a spindle. It is short and narrow. In children in the year of life, its length is 12 cm. There are no glands on the mucosa of the esophagus. Its walls are thin, but it is well supplied with blood. The stomach in young children is located horizontally. And as the child develops, he takes a vertical position. By the age of 7-10, the stomach is already positioned as in adults. The gastric mucosa is thick, and the barrier activity of gastric juice is low compared to adults. The main enzyme of gastric juice is rennet. It provides curdling of milk. The pancreas of a young child is small. In a newborn, it is 5-6 centimeters. In 10 years, it will triple in size. This organ is well supplied with blood vessels. The pancreas produces pancreatic juice. The largest organ of the digestive system of a young child, occupying a third of the abdominal cavity, is the liver. At 11 months, its mass doubles, by 2-3 years it triples. The capabilities of the liver of a child at this age are low. The gallbladder at an early age reaches a size of 3 centimeters. It acquires a pear-shaped form by 7 months. Already at 2 years old, the child's gallbladder reaches the edge of the liver. For children up to a year, substances that come with mother's milk are of great importance. With the introduction of complementary foods to the child, the mechanisms of the child's enzyme systems are activated.

Importance of digestion.

The body needs a regular supply of food. Food contains nutrients: proteins, carbohydrates and fats. In addition, the composition of food includes water, mineral salts and vitamins. Nutrients are necessary for building the living matter of body tissues and serve as a source of energy, due to which all vital processes are performed (muscle contractions, heart function, nervous activity, etc.). In short, nutrients are plastic and energy material for the body. Water, mineral salts and vitamins are not nutrients and a source of energy, but are part of cells and tissues and participate in various life processes. Proteins, carbohydrates and fats in food are complex organic substances and are not absorbed by the body in this form. In the digestive canal, food is subjected to mechanical and chemical influences, as a result of which nutrients are broken down into simpler and more water-soluble substances that are absorbed into the blood or lymph and absorbed by the body. This process of processing food in the alimentary canal is called digestion. Mechanical processing of food consists in its crushing and grinding, which contributes to mixing with digestive juices (food liquefaction) and subsequent chemical processing. Chemical processing - the breakdown of complex substances into simpler ones - occurs under the influence of special substances contained in digestive juices - digestive enzymes. Water, mineral salts and vitamins are not subjected to special treatment in the digestive canal and are absorbed in the form in which they arrive.

44. Neurohumoral regulation of the digestive system.

45. Importance of metabolism and energy.

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 the 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 plays a barrier role in the formation 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.

Young children (especially newborns) have a number of morphological features common to all parts of the gastrointestinal tract: 1) thin, delicate, dry, easily damaged mucous membrane; 2) richly vascularized submucosal layer, consisting mainly of loose fiber; 3) underdeveloped elastic and muscle tissue; 4) low secretory function of the glandular tissue, which separates a small amount of digestive juices with a low content of enzymes. These features 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.

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, fatty bodies (Bish's lumps) in the thickness of the cheeks, which are characterized by considerable 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.

Esophagus. In young children, the esophagus is funnel-shaped. Its length in newborns is 10 cm, in children 1 year old - 12 cm, 10 years old - 18 cm, diameter - 7 - 8, 10 and 12-15 mm, respectively, which must be taken into account when carrying out a number of medical and diagnostic procedures.

Stomach. 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 (Fig. 10-12). 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 sphincter 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 aerophagy"). 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 (Table 3), which not only affects digestion, but also determines the low barrier function of the stomach. 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.

As can be seen from Table. 3, acidity indicators fluctuate significantly, which is explained by the individual characteristics of the formation of gastric secretion and the age of the child.

Determination of acidity is carried out by the fractional method using as an irritant 7% cabbage broth, meat broth, 0.1 % histamine or pentagastrin solution. The main active enzyme of gastric juice is chymosin (rennet, labenzyme), which provides the first phase of digestion - curdling of milk. Pepsin (in the presence of hydrochloric acid) and lipase continue the hydrolysis of proteins and fats of curdled milk. However, the importance of gastric juice lipase in the digestion of fats is small due to its extremely low content in it and low activity. This deficiency is filled with lipase, which is found in women's milk, as well as in the pancreatic juice of the child. Therefore, in infants who receive only cow's milk, fats in the stomach do not break down. 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.

Pancreas. 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 (a- and (beta-amylase, maltase, lactase, etc.). The rhythm of pancreatic secretion is regulated by neuro-reflex and humoral mechanisms. Secretin, which stimulates the separation of the liquid part of pancreatic juice and bicarbonates, and pancreozymin, enhances the secretion of enzymes along with other hormones (cholecystokinin, hepatokinin, etc.) produced by the mucosa 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 secreted juice and its composition depend on the amount and the nature of the food eaten.Intrasecretory function of the pancreas is carried out by synth Eza hormones (insulin, glucagon, lipocaine) involved in the regulation of carbohydrate and fat metabolism.

Liver. In children, the liver is relatively large, its weight in newborns is 4-6% of body weight (in adults - 3%). The liver parenchyma is poorly differentiated, the lobulation of the structure is revealed only by the end of the first year of life, it is full-blooded, as a result of which it rapidly increases in size with various pathologies, especially with infectious diseases and intoxications. By the age of 8, the morphological and histological structure of the liver is the same as in adults.

The liver performs various and very important functions: 1) produces bile, which is involved in intestinal digestion, stimulates the motor activity of the intestine and sanitizes its contents; 2) stores nutrients, mainly excess glycogen; 3) performs a barrier function, protecting the body from exogenous and endogenous pathogenic substances, toxins, poisons, and takes part in the metabolism of medicinal substances; 4) participates in the metabolism and conversion of vitamins A, D, C, B12, K; 5) during fetal development is a hematopoietic organ.

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 newborns, the gallbladder is located deep in the thickness of the liver and has a spindle shape, its length is about 3 cm.

it acquires a 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.

Intestines. 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 intestinal secretory apparatus is generally formed at 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 feces of healthy breastfed newborns have a mushy texture, a golden yellow color, and a sour smell. In older children, the chair is decorated, 1-2 times a day.

Microflora. 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 feeding with mother's milk, the main flora is B. bifidum, the growth of which is promoted by (betta-lactose of human milk. When complementary foods are introduced into the diet or the child is transferred to feeding with cow's milk, gram-negative Escherichia coli, which is a conditionally pathogenic microorganism, predominates in the intestine. therefore, dyspepsia is more often observed in formula-fed children.According to modern concepts, the normal intestinal flora performs three main functions: 1) creating an immunological barrier; 2) final digestion of food residues and digestive enzymes; 3) 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.

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 prerequisites 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, fatty bodies (Bish's lumps) in the thickness of the cheeks, which are characterized by considerable 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 region 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 entrance 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 mucosal fold 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 inferior, 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, 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.

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 the blood directly.

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 epithelial cells 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 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 (they form 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 the appearance characteristic of 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 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 occurs and the formation of water-soluble "direct" bilirubin. 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.

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 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 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 a 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 bifidus 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, it is possible to 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 detected, 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 raspberry - 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 cholangiopancreatography, 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.