Age characteristics digestion in children.

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

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

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

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

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

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

In newborns and children in the first months of life, the oral cavity is relatively small, the tongue is large, the muscles of the mouth and cheeks are well developed, and in the thickness of the cheeks there are fatty bodies (Bishat's lumps), which are distinguished by significant elasticity due to the predominance of solid (saturated) fatty acids in them. These features ensure proper breastfeeding. The mucous membrane of the oral cavity is tender, dry, rich in blood vessels (easily vulnerable). The salivary glands are poorly developed and produce little saliva (the submandibular and sublingual glands function to a greater extent in infants, and in children after one year of age and adults - the parotid glands). The salivary glands begin to function actively by the 3-4th month of life, but even at the age of 1 year, the volume of saliva (150 ml) is 1/10 of the amount in an adult. The enzymatic activity of saliva at an early age is 1/3-1/2 of its activity in adults, but it reaches the level of adults within 1-2 years. Although the enzymatic activity of saliva at an early age is low, its effect on milk promotes its curdling in the stomach to form small flakes, which facilitates the hydrolysis of casein. Hypersalivation at 3-4 months of age is caused by teething; saliva may flow out of the mouth due to the inability of children to swallow it. The reaction of saliva in children of the first year of life is neutral or slightly acidic - this can contribute to the development of thrush of the oral mucosa when improper care for her. At an early age, saliva has a low content of lysozyme, secretory immunoglobulin A, which makes it low bactericidal and requires compliance with proper care behind the oral cavity.

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

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

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

By the time the child is born, the secretory apparatus of the intestine is generally formed; the intestinal juice contains the same enzymes as in adults (enterokinase, alkaline phosphatease, lipase, erypsin, amylase, maltase, lactase, nuclease, etc.), but their activity low. Under the influence of intestinal enzymes, mainly the pancreas, the breakdown of proteins, fats and carbohydrates occurs. However, the pH of duodenal juice in young children is slightly acidic or neutral, so the breakdown of protein by trypsin is limited (for trypsin, the optimal pH is alkaline). Particularly tense the process is underway digestion of fats due to low activity of lipolytic enzymes. In children who are on breastfeeding, bile-emulsified lipids are broken down by 50% under the influence of mother's milk lipase. Digestion of carbohydrates occurs in the small intestine under the influence of pancreatic amylase and intestinal juice disaccharidases. Rotting processes in the intestines do not occur in healthy infants. The structural features of the intestinal wall and its large area determine in young children a higher absorption capacity than in adults and, at the same time, an insufficient barrier function due to the high permeability of the mucous membrane to toxins and microbes.

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

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

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

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

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

The main structural elements of the digestive system are formed in humans by 3-4 months of uterine existence. There is reason to believe that the fetal digestive system is very early subjected to “functional load” due to the entry of amniotic fluid into the gastrointestinal tract. It is possible that the absorption of amniotic fluid is to some extent associated with the regulation of its volume. The liquid, absorbed in the fetal intestines, returns through the placenta into the mother’s blood. It is possible that some of the protein in the amniotic fluid can be absorbed, undergoing hydrolysis, and some can be absorbed unchanged. This is a kind of training for the secretory and motor activity of the digestive canal. The antenatal period is characterized rapid development and improvement of individual components of digestive functions, and development proceeds asynchronously for various departments digestive system.

Functional activity salivary glands manifests itself with the appearance of baby teeth, at the age of 5-6 months. A particularly significant increase in salivation is detected at the end of the first year of life. During the first two years, the formation of baby teeth is intensive. At the age of 2-2.5 years, a child already has 20 teeth and can eat relatively coarse food that requires chewing. The structure of the salivary glands approaches the definitive structure approximately at this age. However, saliva secretion begins immediately after birth. Its physiological meaning lies in the fact that saliva sticks the nipple to the tongue and walls of the mouth and helps create the vacuum necessary for sucking out milk. In addition, mixing milk with saliva promotes the formation in the stomach of not compact, but very small, loose casein clots, which are more accessible for further processing. In a newborn baby, the rate of saliva secretion during sucking increases many times compared to secretion on an empty stomach. With age, the amount of saliva secreted increases. Its maximum amylolytic activity is observed at the age of 2-7 years. The activity of salivary amylase in old age decreases somewhat, but not more than 30-40%, even at the age of 80 years or more. With age, the mineral composition of saliva changes. The potassium content in it remains constant for a long time, only after 40 years it increases slightly. Sodium concentration increases slightly up to 5 years of age. During puberty, the level of this cation in boys becomes higher than in girls. Some excess sodium in men persists even after 40 years. The content of calcium and inorganic phosphorus in humans in mixed saliva during basal secretion shows a tendency to increase with age.

The differentiation of the gastric glands in children is completed mainly by the age of 7, i.e. to the period of replacement of milk teeth with permanent ones, which is important for determining “biological age”. Due to the final approach quality composition When food is added to the diet of an adult, the functions of the entire digestive system are transformed during this period. The function of hydrochloric acid synthesis is detected earlier than enzyme formation, which is associated with the earlier development of parietal cells. However, the acidity of gastric juice in children up to school age remains relatively low. The number of enzymes that break down protein increases especially intensively from 1.5 to 3 years, then at 5-6 years and at school age up to 12-14 years. The hydrochloric acid content increases to 15-16 years. Its low concentration 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 diseases.

Due to the low acidity of gastric juice in infants, pepsin can only break down milk protein. Rennin, or rennet, causes milk to curdle. Gastric juice lipase in infants breaks down no more than 25% of milk fats, but mother's milk lipase, which becomes active in the stomach, also participates in the breakdown of fats. Lipase activity increases with age. The amount and composition of gastric juice depends on the food. Thus, a lot of juice with high acidity is released into meat, and little into fat. When feeding on mother's milk, children secrete gastric juice with low acidity and low digestive power. Up to 10 children, the concentration of free hydrochloric acid in gastric juice increases, then stabilizes and remains constant for 3 years. During puberty, the secretion of hydrochloric acid increases, which is more pronounced in boys.

Sex differences persist until the age of 80, when the amount of free hydrochloric acid in gastric juice in men decreases and becomes the same as in women. At the same time, not only the acidity of gastric juice decreases, but the content of pepsin in it also decreases. In the first two decades of life, enzyme formation increases, reaching a maximum at the age of 21-40. Between 40 and 60 years, the enzyme concentration decreases sharply, and then, until old age, there is a slow decrease in the enzymatic activity of the juice. In children under 10 years of age, absorption processes are actively occurring in the stomach, while in adults these processes are carried out mainly only in the small intestine,

The amylolytic activity of duodenal contents is low during the first year of life, and then, thanks to pancreatic secretions, it exceeds adult levels. Lipolytic activity does not reach the level of an adult even by the age of 12, and proteolytic activity in childhood is even higher than in an adult, and only by the age of 12 it decreases to this level. At the age of 60-70 years, the lipolytic and proteolytic activity of pancreatic secretions decreases. There is evidence of impaired parietal digestion in the small intestine in elderly people, which is caused by weakened intestinal motility. At the same time, the absorption function also suffers.

In early childhood, the child’s liver produces quite a sufficient amount of bile to carry out the part of digestion that depends on it, especially the absorption of milk containing emulsified fat. The gallbladder bile in a child in the first years of life is slightly alkaline, the rate of emptying of the gallbladder is much higher than in adults. Accelerated emptying of the gallbladder is also observed in the elderly compared to mature age. In general, it can be noted that changes in the digestive system in old age, compared to changes, for example, in the vessels and muscles of the body, to a greater extent retain a sufficient, although reduced, “margin of safety.”

All young parents are extremely interested in absolutely everything related to children. Including the characteristics of the digestive system in children. There is no doubt that the digestive system of babies differs from that of adults. But what exactly are these differences? This is exactly what we will try to find out today in this article.

How did it all begin?

And let’s start talking about the features of the digestive system in children from the very beginning, namely, from the moment of implantation of the egg into the mucous membrane of the uterus. After all, even at this stage of development, nutrition for the fetus is simply vital. As soon as the embryo is implanted in the uterus, it begins to feed on a secretion that is produced by the lining of the uterus.

After about a week, the embryo begins to feed on the contents of the yolk sac. And already from about the middle of the second month of pregnancy, the baby’s nutrition becomes hemotrophic - that is, the fetus receives nutrients from the mother’s body, with the help of the placenta.

However, the fetus’s own digestive system does not stand aside - it is directly involved in the processing of nutrients such as protein, water, glucose and others received from the mother’s body. Despite the fact that the maturation of the fetal digestive system occurs extremely quickly, the child is born with very significant physiological immaturity of the salivary glands, pancreas, liver and other organs responsible for proper digestion.

Fortunately, nature is extremely wise. She also provided for this - for the first few months after the baby is born, the only food product for him is mother's milk. Mother's milk is not only easily absorbed by the baby's still immature digestive system, but also completely satisfies all its physiological needs. By the way, all this is true for artificial milk formulas. Although, of course, if it is possible to breastfeed the baby, it is better to give preference to breast milk.

Salivary glands

The anatomical formation of the baby's salivary glands ends at the time of birth. But the secretory function of the salivary glands is still far from ideal. And they will begin to fully function only at 4–5 months. By the way, the active production of saliva that occurs in a child at this age is very often taken by parents as a signal that the baby is starting to cut teeth.

In fact, severe drooling in a baby is due to the pronounced immaturity of the mechanisms that regulate salivation and swallowing. Saliva plays a very important role in the digestion of the baby - the first few months of life it is necessary for the proper sealing of the mouth during sucking. In addition, it is with the help of saliva that small clots of casein, a substance found in breast milk, are formed.

And during the period when the first complementary foods are introduced into the child’s diet, the role of saliva simply cannot be overestimated. It is simply necessary for the correct food bolus to form. If this does not happen, then there is a very high probability that the baby will develop the most various problems with digestion.

Pancreas and liver

By the time a baby is born, its pancreas is still relatively immature. Although it copes very easily with the breakdown of those easily digestible nutrients that are found in breast milk or artificial milk formulas. By the way, if the child is bottle-fed, the maturation of the pancreas occurs much faster. For all other babies who eat mother's milk, the final maturation of the pancreas occurs during the period when complementary foods begin to be introduced into their diet.

It is the pancreas that supplies juice to the duodenum, which contains enzymes such as lipase, which breaks down fats, and trypsin, which breaks down carbohydrates. And, of course, it is the pancreas that produces the hormone insulin, which plays a huge role in the regulation of carbohydrate metabolism. If insulin is produced in insufficient quantities, the likelihood of developing such an unpleasant disease as diabetes is very high.

The pancreas secretes pancreatic juice into the duodenum, which contains enzymes: trypsin, which digests proteins, lipase, which breaks down fats, and amylase, which breaks down carbohydrates. In addition, the pancreas produces the hormone insulin, which is the main regulator of carbohydrate metabolism. With insufficient insulin production, a serious disease develops - diabetes mellitus.

Liver. Despite the fact that the size of a newborn baby's liver is quite large, it is also still far from functional maturity. The secretion of those bile acids that are necessary for the digestion of solid foods is still too small. It begins around the same time when additional complementary foods are introduced into the baby’s diet.

At the time a baby is born, its liver is approximately twice as large as that of an adult. Of course, as a percentage of body size. But, as mentioned above, the baby’s liver is still very, very immature. Although, despite this, the liver successfully copes with many of the functions assigned to it. The liver is a real storehouse of many nutrients, such as fats, glycogen, proteins. And another extremely important function of the liver is antitoxic. It is the liver that is one of the main “filters” that remove all toxic substances from the human body.

Stomach

Despite the fact that the volume of the stomach in a newborn baby increases rapidly, its secretory function is extremely weak. Its full functioning begins at approximately 9–10 months of the baby’s life. Yes, both anatomical and physiological characteristics The stomach crumbs are very peculiar. The fundus of the stomach is extremely poorly developed, as is the entire muscle layer. And here is the entrance to the stomach small child still quite wide.

It is the combination of all these three factors that leads to the fact that young children spit up very often. And vomiting is also a fairly common occurrence. Although, of course, the baby’s swallowing of air during sucking also contributes.

The mucous membrane of a child’s stomach is extremely delicate and is replete with blood vessels. A child's stomach has all the same glands that adults have. And that is why the child’s gastric juice contains almost all the “adult” components, such as rennet, pepsin, hydrochloric acid, lipase and many, many others. However, of course, in a completely different percentage than in adults.

For example, rennet is extremely important for a child’s digestion - it is what causes milk to curdle. By the way, human milk curdles more slowly than cow’s milk, which is the basis for most infant formulas. After the milk has curdled, pepsin comes into play and is designed to break down milk proteins. And the breakdown of fats occurs under the influence of lipase.

Oral cavity

The baby’s oral cavity also has its own characteristics, one way or another connected with sucking milk. The baby's oral cavity itself is still very small - due to the low palate, which does not yet have a vault. The tongue of a small child is wide and short, with pronounced papillae. In addition, the child has extremely well developed chewing muscles.

It is thanks to this whole complex that the baby manages to clasp the nipple very tightly mother's breast. Negative pressure is created in his mouth, due to which milk enters the baby’s oral cavity. If the baby was born full-term, all sucking and swallowing reflexes are very well developed.

The mucous membrane of the child's oral cavity is extremely rich in blood vessels, but very dry. Remember, we said that saliva in babies in the first months of life is not yet produced in full. All food consumed by the child is liquid, so no problems arise.

But here it is worth reminding parents that because increased dryness The oral mucosa is especially sensitive. Therefore, it is necessary to treat it with increased attention and caution. Make sure that the child does not put rough diapers or toys into his mouth. IN otherwise abrasions and wounds may appear on the surface of the child's mucous membrane. These injuries are extremely painful and can result in the baby not being able to suck the amount of milk he needs.

The saliva of a child, like that of any other person, contains various enzymes that begin to break down food in the oral cavity. Of course, we are now talking about complementary feeding, and not about milk.

Intestines

The intestines also play an equally important role in digestion. In children, the intestines compensate for the immaturity of all other organs of the digestive system. After all, it is the child’s intestines that are responsible for membrane digestion, which is so important for a baby who eats mother’s milk or formula. It is in the intestines that the immediate breakdown of nutrients into their components occurs. And from the intestines these same nutrients are absorbed into the blood.

As food enters the stomach is digested, it moves into the intestines under the influence of intestinal peristalsis. Its first stage is the duodenum, where further digestion occurs under the influence of enzymes produced by the pancreas and liver.

Leaving the duodenum, food enters other parts of the small intestine, where it continues to be digested under the influence of intestinal juices. This is where the process of digesting food ends. By the way, the length of a child’s intestines is twice as long as that of an adult – it is six times the height of the baby.

A child’s intestines have very active peristalsis - they make two types of movements:

• Worm-like movements

With help of this type movements move food through various parts of the intestine. Without these movements, the normal digestion process is simply impossible.

• Pendulum-like movements

With the help of pendulum-like movements, the process of digestion of food occurs directly, as well as its subsequent absorption into the blood of a person - in this case, a child.

Normally, intestinal peristalsis in an adult occurs under the influence of food that has entered it. However, in babies, peristalsis can occur and intensify not only due to the mechanical effect of food, but also under the influence of some other factors: prolonged crying of the child, overheating, excessive physical activity.

The mucous membrane of a child's intestines is extremely delicate and sensitive, and its walls have extremely high permeability. That is why for a small child intestinal infections and toxins pose a particular danger. They very quickly penetrate through the intestinal wall into the circulatory system, thereby provoking the development of intoxications, sometimes very strong. In young children, the most common food poisoning can result in such serious consequences as heart failure, meningitis and others.

Microbes of the gastrointestinal tract

During intrauterine development, the baby's intestines are completely sterile. However, just a few hours after birth, the baby’s intestines are colonized by a huge number of a wide variety of bacteria. They disappear into the child’s body through the nose, mouth, and anus. Approximately on the second day after birth, a huge number of a wide variety of bacteria can be found in the baby’s stool. Moreover, there are practically no bacteria either in the stomach or in the upper intestines. They are mainly located in the large intestine and lower part of the small intestine.

Exactly which microbes predominate in the child’s intestines depends solely on the nature of the child’s feeding. If a child is fed mother's milk, which is extremely rich in carbohydrates, the child's intestines will mainly be dominated by those bacteria that are necessary for the fermentation of carbohydrates. It is this microflora that is physiological for an infant.

In the same case, if a child receives artificial milk formulas made from cow's milk, E. coli predominates in his intestines. Unfortunately, this intestinal microflora is no longer physiological for a child. And therefore, under the influence of unfavorable factors, they can provoke the development of various intestinal diseases. That is why most often those children who are bottle-fed suffer from intestinal disorders.

Chair in children

You can’t ignore the question of the baby’s stool. Indeed, in infancy, a baby’s stool can tell a lot about his health. Within physiological norm In the first day or two after birth, the baby should release original feces - meconium. Meconium has a viscous, oily consistency and a dark green color.

Meconium has no odor and is sterile. It is formed in the baby's intestines during intrauterine development - from digestive juices, swallowed amniotic fluid and intestinal epithelium. Normal bowel movements appear around the third day. They consist mainly of the remains of undigested milk, digestive juices, salts and bacteria.

Children in the first months of life usually have stool two to three times a day. However, very often in the first four to five weeks of life, stool occurs much more often - 8 - 9 times a day, sometimes even has a liquid consistency. Of course, almost all mothers get very scared, believing that the baby is very sick. However, if the child’s general well-being does not suffer in any way, the baby eats well and gains weight within the normal range, such frequent bowel movements should not be treated with increased anxiety.

Of course, it is still necessary to tell the doctor or pediatrician about this. However, in most cases, doctors associate this phenomenon with the baby’s insufficiently rapid adaptation to the still new living conditions outside the mother’s body. This happens especially often in babies who were in a hurry to be born, or were born weak and with low body weight.

However, the opposite situation also happens, in which babies who feed on the same mother’s milk have stool only once every two to three days. And this can be explained very simply - mother’s milk is digested very well. And it is absorbed almost completely, which means there is practically no waste left.

By the way, those babies who eat artificial mixtures made from cow's milk, feces have more dark color, thick consistency or more bad smell. As the child gets older, stool becomes less and less frequent. However, of course, the full maturity of digestion is still very far away. Full maturation of the digestive tract ends only by 15–16 years. Until then, parents will have to constantly take into account the digestive characteristics of their children when compiling their menu.

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ANATOMICAL AND PHYSIOLOGICAL FEATURES OF THE GASTROINTESTINAL TRACT IN CHILDREN

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

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

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

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

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

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

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

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

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

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

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

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

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

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

M.Yu. Buslaeva

Issues of aggression and aggressive behavior are relevant in scientific literature and are considered from the point of view of philosophy, pedagogy and psychology. Until the beginning of the 19th century, any active behavior, both benevolent and hostile, was considered aggressive. Later, the meaning of this word changed and became narrower. But, nevertheless, in modern psychology there is a problem of defining aggression and aggressiveness, because these terms imply a wide variety of actions.

Development of independence of children of senior preschool age in research activities

A.S. Mikerina
The relevance of the problem under consideration is explained by the fact that modern society needs citizens who are distinguished by purposefulness, observation, erudition, and the ability to find a way out difficult situation, mobility. In this regard, education is aimed at developing in children independence, activity in understanding the world around them, and a subjective position in activity. Federal State educational standard preschool education emphasizes the need to develop children's independence preschool age in types of activity specific to them: gaming, communicative, motor, visual, cognitive research, etc.

Educational activities in preschool educational organizations

I.Yu. Ivanova

One of the pressing problems of modern preschool education is the formation of parental competence in matters of development and education of preschool children. This is reflected in the “Strategy for the Development of Education in Russian Federation for the period until 2025", where the creation of conditions for educating and consulting parents on legal, economic, medical, psychological, pedagogical and other issues family education named one of the strategic goals. However, despite the increased attention of the state to solving this problem, there is a tendency in society to reduce the spirituality and cultural level of adults and children, the collapse of the system family values raising children.

Preparing parents for productive communication with children of senior preschool age

L.I. Savva

The family and, first of all, parents, their behavior and life values ​​are the main source of transferring social experience to the child, as well as the knowledge, skills and abilities necessary for constructing social contacts and relationships between people. Through the system of intrafamily relationships, a preschool child develops his own views, attitudes, ideas, masters moral standards and learns to understand social situations.

Theoretical and methodological foundations of personal development of children of senior preschool age in the process of organized communicative activities

O.G. Filippova

The existing transformations in the country have led to changes in the modern goals and values ​​of education. The information and communication era of today's world has made it possible to determine the need for every linguistic personality to strive for communicative and creative development and personal development. Starting from preschool age, it is important to develop in children the ability to establish positive relationships between people, to adequately perceive and evaluate ongoing relationships and events, as well as to know themselves and others in communication through their own speech actions and awareness of their role and place in the multicultural environment.

The fetus, starting from 3 to 4 months, makes swallowing movements, swallowing amniotic fluid containing proteins, sugars, urea, minerals and hormones. From these substances, as well as from the digestive juices of the intestine and bile, it forms original feces - meconium.

Oral cavity

The digestive system begins with the oral cavity, which in newborns and young children is relatively small, covered with a delicate, rich in blood vessels, bright pink mucous membrane. The oral cavity of a newborn baby has some peculiarities. Thus, the mucous membrane of the lips with transverse folds contributes to better coverage of the nipple during sucking. The act of sucking and the creation of negative pressure in the oral cavity are facilitated by noticeably expressed fat lumps located in the thickness of the cheeks - the so-called Bichat pads and roller-like thickenings on the gums.

The act of sucking consists of three successive phases: aspiration (creating a vacuum in the oral cavity), squeezing the nipple and swallowing milk. Covering the nipple and part of the isola with his lips, the child, with the movement of his tongue and lower jaw, creates a vacuum in the oral cavity, which is supported by Bisha's pads, then presses his jaws on the area of ​​the isola, squeezes milk out of the exit ducts of the milk passages and swallows it. Each swallowing movement is preceded by several sucking movements.

During the act of sucking, the child also swallows a certain amount of air, which, rising up the esophagus, can cause belching or, if part of the milk from the stomach is captured along with it, regurgitation. Therefore, after breastfeeding, the baby must be held in an upright position for some time until the air he swallowed with food comes out.

Salivary glands

The salivary glands in a newborn baby are underdeveloped and produce little saliva, which explains the dryness of the oral mucosa. Already in the saliva of a newborn small quantity the digestive enzyme amylase is detected, which is subsequently necessary for the digestion of complex carbohydrate compounds, such as starch, as well as lysozyme, a substance that performs the immunological protective function of the body. A newborn's saliva helps curdle milk in the stomach into more delicate flakes, and also acts as a sealant for the oral cavity during the act of sucking.

During the early development of a child, as his body develops, the salivary glands increase, the number of secreting cells in them increases and, accordingly, the amount of saliva and its enzymatic activity. This process continues until the age of 10. But already at the age of 3-4 months, the salivary glands reach significant development and it is during this period that children experience constant (physiological) salivation. This is explained by the fact that a lot of saliva is secreted, and the ability to swallow has not yet been fully developed. The highest enzymatic activity of saliva is observed in children aged 2-7 years. The secretion of saliva is also influenced by the nature of food. For example, more saliva is secreted into cow's milk than into women's milk, and into fermented milk mixtures - twice as much as into cow's milk.

Newborn tongue

The tongue of a newborn is short, wide, relatively large in size, with three distinct muscle layers and a developed network of blood and lymphatic vessels. On the surface of the tongue there are papillae with taste buds.

The newborn's hard palate is flat. The soft palate is located more horizontally than in adults. The pharynx is almost at the same level with the hard palate.

Tonsils

The tonsils develop most intensively during the first year of life, and at the age of 2-3 years they often become significantly hypertrophied and, closing the nasopharyngeal openings, make breathing difficult. After 14-16 years, the size of the tonsils already corresponds to the size of the tonsils of an adult.

Teeth

Children develop teeth at the age of 6-8 months, that is, during the period when the diet begins to change. Milk teeth (20 in total) erupt in the following sequence: at 6-8 months - the lower middle incisors, after another 1 - 1.5 months - the upper middle incisors, then the upper lateral and lower lateral incisors. By the end of the first - beginning of the second year of life, a child usually has 8 teeth, and by two years - 20 teeth. Small molars erupt at 12 - 15 months, canines - at 17 - 20 months, and by the end of the second year of life - second small molars. From 5 to 6 years of age, the process of loss of baby teeth and development of permanent teeth begins.

Esophagus

The esophagus in newborns and young children has a funnel shape. The upper part of the esophagus is flattened (this is due to the bilateral pressure of the trachea and spine), in the middle so-called cardiac part it is expanded, and closer to the stomach it takes on a cylindrical shape. The muscle layers are poorly developed. The delicate mucous membrane covering its inner surface is rich in blood vessels. The mucous glands are poorly developed, so the inner surface of the esophagus is always dry and easily wounded. As the child develops, not only the size, but also the shape of the organ changes - the funnel shape disappears and the esophagus, characteristic of an adult, gradually forms.

Stomach

The newborn's stomach, located in the left hypochondrium, has a cylindrical shape. Its muscle layer is poorly developed, the entrance to the stomach is wide, and this greatly contributes to the regurgitation of food. During the first year of life, the baby's stomach is horizontal. From the moment the child begins to walk, the stomach gradually takes on a vertical position. The mucous membrane is thick, with faint folds and a dense network of blood vessels. The muscle layer is moderately developed. The secretory glands of a child’s stomach produce the same digestive juices as those of an adult, only their activity is much lower. Digestion of incoming food in the stomach in young children occurs with low acidity, since the secretory cells of the mucous membrane produce an insufficient amount of hydrochloric acid. The digestion of proteins is facilitated by the enzymes contained in the gastric juice - chymosin, gastrixin, pepsin, cathepsin.

Depending on the nature of feeding, the activity of the protein digestion process also changes. It is known that when translating into artificial feeding The acidity of gastric juice and the activity of enzymes that break down proteins gradually begin to increase. This indicates significant functional reserves of the secretory glands of the stomach in full-term young children. Already by 8-10 months of age, the acidity of gastric juice and its digestive activity in relation to proteins increases significantly, by 3 years it approaches the levels of an adult and by 10-13 years it becomes the same as in adults.

Digestion of fats in the stomach in young children occurs mostly with the participation of the enzyme lipase, which is found in significant quantities in breast milk. At the same time, the fats of cow's milk in the stomach of young children are almost not digested, and therefore are not absorbed, because the activity of gastric lipase is insufficient for their digestion. Carbohydrates supplied with food are partially broken down in the stomach by the action of the salivary enzyme amylase. Evacuation of food from the stomach in newborns and infants is slow, which is explained by the imperfection of nervous regulatory mechanisms. With natural feeding, the stomach is empty of food after 2.5 hours, and with artificial feeding, this period is extended and amounts to 3-4 hours.

In the first months of life, the stomach grows especially rapidly. Its capacity increases noticeably with age. In a full-term newborn it is 30-35 ml, at 3 months - 100 ml, at 12 months - 250-300 ml, at 2-3 years - 400-600 ml. By the tenth year of life, the stomach takes on the shape characteristic of the stomach of an adult.

Based on materials from the book by Deryugina M.P.

"Diet food for children"