In the extrauterine period, the gastrointestinal tract is the only source of 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 digestive system

In children early age(especially newborns) there are a number of morphological features common to all parts of the gastrointestinal tract:

• thin, tender, dry, easily wounded mucous membrane;
• richly vascularized submucosal layer, consisting mainly of loose fiber;
• underdeveloped elastic and muscle tissue;
• low secretory function of glandular tissue, separating 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 is not appropriate for the child’s age, reduce the barrier function of the gastrointestinal tract and lead to frequent illnesses, create the preconditions for a general systemic reaction to any pathological impact and require very careful and thorough care of the mucous membranes.

Oral cavity in a child

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 muscles of the mouth and cheeks, roller-like duplications of the mucous membrane of the gums and transverse folds on the mucous membrane of the lips, fatty bodies (Bishat's lumps) in the thickness of the cheeks, characterized by significant elasticity due to the predominance of solid fatty acids in them. 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 3-4 months of age, a child often develops 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, with transverse ridges on their inner surface. The orbicularis oris muscle 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 fat body (Bishat's fat pads), 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 velum palatine does not touch the back wall of the pharynx, which allows the baby to breathe while sucking. With the appearance of baby teeth, there is a significant increase in the size of the alveolar processes of the jaws, and the vault of the hard palate seems to rise. 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, and protrudes forward between the jaws at the vestibule of the mouth.

Oral mucosa

The oral mucosa in children, especially young children, is thin and easily vulnerable, which must be taken into account when treating the oral cavity. The mucous membrane of the floor 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, transverse folds (ridges) are also present on the hard palate, roller-like thickenings are on the gums. All these formations provide sealing of the oral cavity during sucking. On the mucous membrane in the area of ​​the hard palate in the midline of newborns there are Bohn's nodes - yellowish formations - retention cysts of the salivary glands, disappearing by the end of the first month of life.

The oral mucosa in children in the first 3-4 months of life is relatively dry, which is due to insufficient development of the salivary glands and a deficiency of saliva. The salivary glands (parotid, submandibular, sublingual, small glands of the oral mucosa) in a newborn are characterized by low secretory activity and secrete very a 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 leaks from the mouth due to the immaturity of the regulation of salivation and swallowing of saliva (physiological drooling). The most intensive growth and development of the salivary glands occurs between 4 months and 2 years. By the age of 7, a child produces the same amount of saliva as an adult. The saliva reaction 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.

Pharynx 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 the C and | and C 1 V . By adolescence, it drops to the level C vl -C VII. The larynx in infants also has a funnel shape and is located differently than in adults. The entrance to the larynx is located high above the infero-posterior edge of the velum palatine 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.

Baby's sucking and swallowing

Sucking and swallowing are congenital unconditioned reflexes. In healthy and mature newborns, they are already formed at the time of birth. When sucking, the baby's lips tightly grasp the nipple. The jaws squeeze it, and the communication between the oral cavity and the outside air stops. Negative pressure is created in the child’s mouth, which is facilitated by lowering 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 newborn’s masticatory apparatus are adapted for the process of breastfeeding: the gingival membrane, pronounced palatal transverse folds and fat bodies in the cheeks. The adaptation of the newborn's oral cavity to sucking also serves as physiological infantile retrognathia, which later turns into orthognathia. During the sucking process, the baby makes rhythmic movements of the lower jaw from front to back. The absence of an articular tubercle facilitates sagittal movements of the child’s lower jaw.

Child's esophagus

The esophagus is a spindle-shaped muscular tube lined on the inside with 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 the length of the body remains relatively constant and is approximately 1:5. The width of the esophagus in a newborn is 5-8 mm, at 1 year - 10-12 mm, by 3-6 years - 13-15 mm and by 15 years - 18-19 mm. The size of the esophagus must be taken into account during fibro-esophageal-gastroduodenoscopy (FEGDS), duodenal intubation and gastric lavage.

Anatomical narrowing of the esophagus in newborns and children of the first year of life is weakly expressed and develops with age. The wall of the esophagus in a newborn is thin, the muscular layer is poorly developed, it grows rapidly until the age of 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 and rich in blood vessels.

Outside of the act of swallowing, the transition from the pharynx to the esophagus is closed. Peristalsis of the esophagus occurs during swallowing movements.

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

When carrying out anesthesia and the process of intensive therapy, probing of the stomach is often performed, so the anesthesiologist must know the age-related dimensions of the esophagus (table).

Table. Dimensions of the esophagus in children depending on age

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

Gastric capacity increases in proportion to age up to 1-2 years. Further increase is associated not only with body growth, but also with dietary habits. Approximate values ​​of gastric capacity in newborns and infants are presented in the table.

Table. Gastric capacity in young children

What is the size of the esophagus in children?

The indicated 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.

Physiology of gastric secretion in children of different ages in principle no different from that in adults. The acidity of gastric juice may be slightly lower than in adults, but this often depends on the nature of the diet. The pH of gastric juice in infants is 3.8-5.8, in adults at the height of digestion it is up to 1.5-2.0.

Gastric motility 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 it takes for food (chyme) to pass 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. At artificial feeding In infants, digestion time can take up to 48 hours.

Baby's stomach

Features of a child's stomach

The stomach of a newborn has the shape of a cylinder, a bull's 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 in a vertical position) is projected between T X | and T X|| , and the output is between T x|| and L,. In infants, the stomach is positioned horizontally, but as soon as the child begins to walk, it gradually takes on a more vertical position.

The cardial part, fundus and pyloric part of the stomach in a newborn are poorly expressed, the pylorus is wide. The inlet part of the stomach is often located above the diaphragm, the angle between the abdominal part of the esophagus and the adjacent wall of the fundus of the stomach is not sufficiently pronounced, and the muscular lining of the cardia of the stomach is also poorly developed. The Gubarev valve (a fold of the mucous membrane that protrudes into the cavity of the esophagus and prevents the reverse reflux of food) is almost not expressed (develops by 8-9 months of life), the cardiac sphincter is functionally defective, while the pyloric part of the stomach is functionally well developed already at the birth of the child.

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

In the first weeks of life, the stomach is located in the 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 anthralopyloric region, 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 takes on 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 a newborn's stomach 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 it 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 - to 80 ml. Subsequently, the stomach capacity increases by 25 ml monthly and by the end of the first year of life it is 250-300 ml, and by 3 years - 400-600 ml. An intensive increase in stomach capacity begins after 7 years and by 10-12 years it is 1300-1500 ml.

The muscular lining of the stomach in a newborn is poorly developed; it reaches its maximum thickness only by 15-20 years. The mucous membrane of the stomach of a newborn is thick, the folds are high. During the first 3 months of life, the surface of the mucous membrane increases 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 into which the openings of the gastric glands open increases. At birth, the gastric glands are morphologically and functionally insufficiently developed; their relative number (per 1 kg of body weight) in newborns is 2.5 times less than in adults, but quickly increases with the start of enteral nutrition.

The secretory apparatus of the stomach in children of the first year of life is not sufficiently developed, 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 (curds milk), pepsins (breaks 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.e. when switching from lactotrophic nutrition to regular nutrition. In parallel with the decrease in gastric juice pH, the activity of carbonic anhydrase, which is involved in the formation of hydrogen ions, increases. In children during 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 main 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 higher proteolytic activity. In infants, significant fluctuations in the activity of proteolytic enzymes were noted depending on the nature of feeding (with artificial feeding, the activity levels are higher). In children of the first year of life (unlike adults), 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 of newborns and infants determine the reduced protective function of gastric juice, but at the same time contribute to the preservation of Ig that comes 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 actively increases and stabilizes after 3 years. By the age of 2 years, the structural and physiological characteristics of the stomach correspond to those of an adult. In infants, it is possible to increase the tone of the stomach muscles in the pyloric region, the maximum manifestation of which is pyloric spasm. Cardiospasm is sometimes observed in older people. The frequency of peristaltic contractions in newborns is the lowest, then actively increases and stabilizes after 3 years.

In infants, the stomach is located horizontally, with the pyloric part located 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 stomach capacity of newborns is 30 - 35 ml, by 1 year it increases to 250 - 300 ml, by 8 years it reaches 1000 ml. The cardiac sphincter in infants is very poorly developed, but the pyloric sphincter functions satisfactorily. This contributes to regurgitation, which is often observed at this age, especially when the stomach is distended due to swallowing air during sucking ("physiological aerophagia"). There are fewer glands in the gastric mucosa of young children than in adults. And although some of them begin to function 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 the low barrier stomach function. This makes it absolutely necessary to carefully observe the sanitary and hygienic regime while feeding children (breast toilet, clean hands, proper expression of milk, sterility of nipples and bottles). IN last years It has been established that the bactericidal properties of gastric juice are provided by lysozyme produced by the cells of the surface epithelium of the stomach.

Maturation of the secretory apparatus of the stomach occurs earlier and more intensely in children who are bottle-fed, which is associated with the body’s adaptation to more difficult to digest food. The functional state and enzyme activity depend on many factors: the composition of the ingredients and their quantity, the emotional tone of the child, his physical activity, and general condition. It is well known that fats suppress gastric secretion, 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 partly the products of protein breakdown. Gastric motility in children in the first months of life is slow, peristalsis is sluggish, and the gas bubble is enlarged. The timing of food evacuation from the stomach depends on the nature of feeding. Thus, women's milk lingers in the stomach for 2-3 hours, cow's milk for a longer time (3-4 hours and even up to 5 hours, depending on the buffering properties of milk), which indicates the difficulties of digesting the latter and the need to switch to less frequent feedings.

Child's intestines

The intestine starts from the pylorus of the stomach and ends at the anus. There are small and large intestines. The small intestine is divided into duodenum, jejunum and ileum; large intestine - into the cecum, 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, and in adults it is only 10 cm.

In children, the intestine is relatively longer than in adults (in an infant it is 6 times the length of the body, in adults - 4 times), but its absolute length varies widely individually. The cecum and appendix are mobile, the latter is often located atypically, thereby complicating diagnosis during inflammation. The sigmoid colon is relatively longer than in adults, and in some children it even forms loops, which contributes to the development of primary constipation. With age, these anatomical features disappear. Due to weak fixation of the mucous and submucous membranes of the rectum, it may fall out with persistent constipation and tenesmus in weakened children. The mesentery is longer and more easily extensible, due to which torsions, intussusceptions, etc. easily occur. The omentum in children under 5 years of age is short, so the possibility of localizing peritonitis in a limited area abdominal cavity almost excluded. Among the histological features, it should be noted that the villi are well expressed and there are an abundance of small lymphatic follicles.

All intestinal functions (digestive, absorption, barrier and motor) in children differ from those in adults. The digestion process, 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 colossus is generally formed by the time the child is born, and even in the smallest children the same enzymes are detected in the intestinal juice as in adults (enterokinase, alkaline phosphatase, erepsin, lipase, amylase, maltase, lactase, nuclease), but significantly less active. The large intestine secretes only mucus. Under the influence of intestinal enzymes, mainly the pancreas, the breakdown of proteins, fats and carbohydrates occurs. Particularly tense the process is underway digestion of fats due to the low activity of lipolytic enzymes.

In children who are on breastfeeding, bile-emulsified lipids are broken down by 50% under the influence of mother's milk lipase. Digestion of carbohydrates occurs in the small intestine parietally 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 sugars does not undergo enzymatic breakdown and is converted into lactic acid in the large intestine by bacterial decomposition (fermentation). Rotting processes do not occur in the intestines of healthy infants. Hydrolysis products formed as a result of cavity 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 are determined in children younger age higher absorption capacity than in adults and at the same time insufficient barrier function due to the high permeability of the mucous membrane to toxins, microbes and other pathogenic factors. Ingredients are the easiest to digest human milk, the protein and fats of which are partially absorbed undigested in newborns.

The motor (motor) function of the intestine is carried out in children very energetically due to pendulum-like movements that mix food, and peristaltic movements that move 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 a voluntary act. In the first 2 - 3 days after birth, the baby secretes meconium (original feces) of a greenish-black color. It consists of bile, epithelial cells, mucus, enzymes, ingested amniotic fluid. Feces of healthy newborns who are natural feeding, have a mushy consistency, golden-yellow color, and sourish odor. In older children, stools are formed, 1-2 times a day.

Duodenum of a child

The duodenum of a newborn has a ring shape (curves are formed later), its beginning and end are located at level L. In children older than 5 months, the upper part of the duodenum is at level T X|1; the descending part gradually falls 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 formed in the intestines, and mixed with bile. The folds of the duodenal mucosa in newborns are lower than in older children, the duodenal glands are small and less branched than in adults. The duodenum has a regulating effect on the entire digestive system through hormones secreted by the endocrine cells of its mucous membrane.

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 the ileocecal valve (bauginian valve). In young children, a relative weakness of the ileocecal valve is noted, and therefore the contents of the cecum, the richest in bacterial flora, can be thrown into the ileum, causing a high frequency of inflammatory lesions of its terminal section.

The small intestine in children occupies a variable position, depending on the degree of its filling, body position, intestinal tone and muscles of the anterior abdominal wall. Compared to adults, the intestinal loops lie more compactly (due to the relatively large sizes liver and underdevelopment of the 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 they completely disappear by the age of 7 (adults normally do not have gases in the small intestine).

The mucous membrane is thin, richly vascularized and has increased permeability, especially in children of the first year of life. The 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 of adults by 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 subsequently are grouped mainly in the ileum in the form of group lymphatic follicles (Peyer's patches). Lymphatic vessels are numerous and have a wider lumen than in adults. Lymph flowing from the small intestine does not pass through the liver, and absorption products enter directly into the blood.

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

In the small intestine, the main stages of the complex process of breakdown 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 (cavitary 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 at birth. Even in newborns, the same enzymes can be detected 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 absorption 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 a slightly changed form, which can lead to the appearance of AT to cow's milk proteins. In children over a year old proteins undergo hydrolysis to form amino acids.

From the first days of a child’s life, all parts of the small intestine have fairly high hydrolytic activity. Disaccharidases appear in the intestine in the prenatal period. The activity of maltase is quite high at birth and remains so in adults; the activity of sucrase 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 last weeks 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, and it is lowest in adults. It should be noted that lactose from human milk is absorbed more slowly than oslactose from cow's milk and partially enters the colon, which contributes to the formation of gram-positive intestinal microflora in breastfed children.

Due to low lipase activity, the process of fat digestion 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 superficial layer of the mucous membrane of the small intestine.

Baby's colon

The colon of 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 child’s height. By birth, the large intestine does not complete its development. The newborn does not have omental processes (appear in the 2nd year of the child’s life), the ribbons of the colon are barely visible, and the haustra of the colon are absent (appear after 6 months). The bands of the colon, haustra and omental processes are finally formed by 6-7 years.

The cecum 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 cecum is located, the more underdeveloped the ascending colon is. The ileocecal valve in newborns looks like small folds. The ileocecal opening is ring-shaped or triangular, gapes. In children older than one year, it becomes slit-like. The vermiform appendix in a newborn has a cone-shaped shape, the entrance to it is wide open (the valve is formed in the first year of life). The vermiform 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 loops of the small intestine. Its ascending part in a newborn is very short (2-9 cm) and increases after the large intestine 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) and only by the age of 2 it occupies 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 gains the ability to easily move when filling the stomach and small intestine. The descending colon of a newborn has a smaller diameter than other parts of the colon. It is poorly 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 shortening of the mesentery and the accumulation of adipose tissue around it. The large intestine provides water resorption and evacuation-reservoir function. In it, the absorption of digested food is completed, the remaining substances are broken down (both under the influence of enzymes coming from the small intestine and bacteria inhabiting the large intestine), and feces are formed.

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

Baby's rectum

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

Functional Features baby's intestines

The motor function of the intestine (motility) consists of pendulum-like 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 antiperistaltic movements that thicken and form feces.

Motor skills in young children are more active, which contributes to frequent bowel movements. In infants, the duration of passage of food gruel through the intestines ranges 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 out - a sticky mass of dark green color with a pH of about 6.0. Meconium consists of desquamated epithelium, mucus, amniotic fluid residues, bile pigments, etc. On the 2-3rd day of life, feces are mixed with meconium, and from the 5th day, feces take on the appearance characteristic of a newborn. In children in 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, bowel movements are less frequent.

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

In infants, defecation occurs reflexively, without the participation of the will. From the end of the first year of life healthy child gradually learns that defecation becomes a voluntary act.

Pancreas

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

In a newborn, the pancreas is located deep in the abdominal cavity at the T x level, 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 young and older children, the pancreas is at the level of Ln. The gland grows most intensively in the first 3 years and during puberty.

By birth and in the first months of life, the pancreas is insufficiently differentiated, highly vascularized and poor in connective tissue. At an early age, the surface of the pancreas is smooth, and by the age of 10-12 years, tuberosity appears due to the separation of the boundaries of the lobules. The lobes and lobules of the pancreas in children are smaller in size and few in number. The endocrine part of the pancreas is more developed at birth than the exocrine part.

Pancreatic juice contains enzymes that provide 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 increases several times from birth to 1 year of age. When switching to a normal diet, in which more than half of the calorie needs are 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 large role of lipase from the salivary glands, gastric juice and breast milk lipase in the hydrolysis of fat. The activity of lipase in duodenal contents increases towards the end of the first year of life and reaches adult levels by 12 years. The proteolytic activity of pancreatic secretions in children in the first months of life is quite high, reaching a maximum at the age of 4-6 years.

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

In a newborn, the pancreas is small in size (length 5 - 6 cm, by 10 years - 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 first 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 and consists of fine-fibrous structures, and therefore compression of the pancreas is rarely observed in children with inflammatory edema of the pancreas. 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 into the duodenum, often leads to a friendly reaction from the organs of this zone with wide irradiation 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 digesting 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 secretion of adults by 5 years of age. The total volume of juice secreted and its composition depend on the amount and nature of the food eaten. The intrasecretory function of the pancreas is carried out through the synthesis of hormones (insulin, glucagon, lipocaine) involved in the regulation of carbohydrate and fat metabolism.

Liver in children

Liver sizes in children

At the time of birth, the liver 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 liver weight 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 liver weight doubles by 8-10 months and triples by 2-3 years.

Due to the different rate of increase in liver and body weight in children from 1 to 3 years of age, the edge of the liver emerges from under the right hypochondrium and is easily palpable 1-3 cm below the costal arch along the midclavicular line. From the age of 7 years, the lower edge of the liver does not protrude from under the costal arch and is not palpable in a quiet position; along the midline does not extend beyond the upper third of the distance from the navel 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 lobular structure is revealed only at 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 full of blood, as a result of which it quickly enlarges during infections and intoxications, and circulatory disorders. The fibrous capsule of the liver is thin.

About 5% of the liver volume in newborns is made up of hematopoietic cells, subsequently their number quickly decreases.

A newborn's liver contains 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.

Liver functions in a child’s body

The liver performs various and very important functions:

• produces bile, which is involved in intestinal digestion, stimulates intestinal motor activity 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 transformation of vitamins A, D, C, B12, K;
• during intrauterine development is a hematopoietic organ.

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

The neonatal period is characterized by immaturity of all stages of the hepatic intestinal circulation of bile acids: insufficiency of their uptake by hepatocytes, excretion through the canalicular 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 increased permeability of intercellular connections and 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 predominantly with taurine (in adults, with glycine). Taurine conjugates are more soluble in water and less toxic. The 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.

The enzyme systems of the liver, which ensure 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 albuminoglobulin ratio in the blood.

In children, transamination of amino acids occurs in the liver much more actively: 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 transamination processes are not mature enough, and the number of essential acids for children is greater than for adults. So, adults have 8 of them, children under 5-7 years of age 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 3-4 months of life; before this, children experience high urinary excretion of ammonia with low urea concentrations.

Children of the first year of life are resistant to ketoacidosis, although they receive foods 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 significantly lower than in the mother. After the start of breastfeeding, hypercholesterolemia is observed for 3-4 months. Over the next 5 years, cholesterol concentrations in children remain lower than in adults.

In newborns in the first days of life, insufficient activity of glucuronyl transferase is noted, with the participation of which bilirubin is conjugated with glucuronic acid and the formation of water-soluble “direct” bilirubin occurs. 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 coming from the intestines, and takes part in the metabolism of drugs. In young children, the detoxifying function of the liver is not sufficiently developed.

Liver functionality in young children is relatively low. Its enzymatic system is especially ineffective in newborns. In particular, the metabolism of indirect bilirubin, released during hemolysis of red blood cells, is not complete, resulting in physiological jaundice.

Gallbladder in a child

The gallbladder in newborns is usually hidden by the liver; its shape can be different. Its size increases with age, and by 10-12 years its length approximately doubles. The rate of bladder bile secretion 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 composition of the bile of children differs from that 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 a child’s bile is the predominance of taurocholic acid over glycocholic acid, since taurocholic acid enhances the bactericidal effect of bile and also accelerates the secretion of pancreatic juice. Bile emulsifies fats, dissolves fatty acids, and improves peristalsis.

Child's intestinal microflora

During intrauterine development, the fetal intestine is sterile. It is colonized by microorganisms 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 scant bacterial flora. In the small and especially large intestines 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 (3-lactose of human milk. When complementary foods are introduced into the diet or a child is transferred to feeding with cow's milk, gram-negative Escherichia coli, which is an opportunistic microorganism, predominates in the intestines. this is why dyspepsia is more often observed in children who are bottle-fed.According to modern concepts, normal intestinal flora performs three main functions:

Creation of an immunological barrier;

Final digestion of food debris and digestive enzymes;

Synthesis of vitamins and enzymes.

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

Historical data on the intestinal microflora

The study of intestinal microflora began in 1886, when F. Escherich described Escherichia coli (Bacterium coli coli). The term “dysbacteriosis” was first introduced by A. Nissle in 1916. Subsequently positive role normal intestinal microflora in the human body was proven 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. Dorofeychuk et al. (1986), B. A. Shenderov et al. (1997).

Characteristics of intestinal microflora in children

The microflora of the gastrointestinal tract takes part in digestion, prevents the development of pathogenic flora in the intestines, 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 intestines with microorganisms begins (the second phase), and the third phase - stabilization of the microflora - lasts at least 2 weeks. The formation of the intestinal microbial biocenosis begins from the first day of life; by the 7th-9th day in healthy full-term children, the bacterial flora is usually represented mainly by Bifidobacterium bifldum, Lactobacillus acidophilus. During natural feeding, B. bifidum predominates among the intestinal microflora; during artificial feeding, L. acidophilus, B. bifidum and enterococci are present in almost equal quantities. 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, the basis of which is 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 proliferation of putrefactive and pathogenic flora;
• normalizes intestinal motility;
• participates in the processes of digestion, metabolism, detoxification of xenobiotics;
• has 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 (opportunistic and saprophytic microorganisms); transient (occasional microorganisms incapable of long-term residence 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, make up 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 quality composition indigenous microflora in microbiocenosis.

Intestinal dysbiosis is a violation of the relationship between anaerobic and aerobic microflora in the direction of a decrease in the number of bifidobacteria and lactobacilli, normal E. coli and an increase in the number of microorganisms found in a small amount or usually absent from the intestines (opportunistic microorganisms).

Methodology for studying the digestive organs

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

inspection and observation over time;

palpation;

percussion;

laboratory and instrumental indicators.

Child's complaints

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

Questioning a child

Questioning the mother directed by the doctor makes it possible to clarify the time of onset of the disease, its connection with dietary habits and regimen, previous diseases, and family and hereditary nature. Of particular importance is a detailed clarification of feeding issues.

Abdominal pain is a common symptom reflecting a variety of pathologies childhood. Pain that occurs 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-bacterial intestinal infections, urinary tract inflammation, pleuropneumonia, rheumatism, pericarditis, Henoch-Schönlein disease, periarteritis nodosa. Recurrent abdominal pain in older children is observed in diseases such as gastritis, duodenitis, cholecystitis, pancreatitis, gastric and duodenal ulcers, and ulcerative colitis. Functional disorders and helminthic infestation may also be accompanied by abdominal pain.

Decreased or prolonged loss of appetite (anorexia) in children is often the result of exposure to psychogenic factors (overload at school, conflict situation in the family, neuroendocrine dysfunction of puberty), including improper feeding child (force feeding). However, usually a decrease in appetite indicates low gastric secretion and is accompanied by trophic and metabolic disorders.

Vomiting and regurgitation in newborns and infants can be a consequence of pyloric stenosis or pyloric spasm. In healthy children of this age, frequent regurgitation is caused by aerophagia, which is observed when feeding techniques are violated, a short frenulum of the tongue, or tight breasts 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. Vomiting may occur due to damage to the central nervous system, infectious diseases, or poisoning.

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

Constipation is rare bowel movements that occur after 48 hours or more. They can be a consequence 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 stomach, liver and bile ducts. Nutritional (consumption of food low in fiber) and infectious factors are of certain importance. Sometimes constipation is associated with the habit of delaying bowel movements and, as a result, a 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 who are 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 protrudes slightly above the level chest, and subsequently flattens out somewhat. An increase in abdominal size can be explained by a number of reasons:

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

The shape of the abdomen also has diagnostic significance: its uniform increase is observed with flatulence, hypotonia of the muscles of the anterior abdominal wall and intestines ("frog" belly - with rickets, celiac disease), local bulging with hepatolienal syndrome of various etiologies, tumors of the abdominal cavity and retroperitoneal space. Recession of the abdomen can be observed when the child is starving, pyloric stenosis, meningitis, diphtheria. Upon examination, you can determine the condition of the navel in newborns, the expansion of the venous network in cirrhosis of the liver, the divergence of the muscles of the white line and hernial protrusions, and in malnourished children in the first months of life - intestinal peristalsis, 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 with the patient in the supine position with slightly bent legs, warm hand, starting from the navel area, 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 abdominal wall tension. With deep palpation, the presence of painful points, infiltrates is revealed, the size, consistency, nature of the surface of the lower edge of the liver and spleen, enlargement of mesenteric lymph nodes in tuberculosis, lymphogranulomatosis, reticulosis and other diseases, spastic or atonic condition of the intestine, and accumulation of feces are determined.

Palpation is also possible with the child in an upright position with a half-tilt forward and arms down. In this case, the liver and spleen are well palpated, and 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 baby's abdomen

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

The anal area is examined in younger children in the lateral position, in the rest - in the knee-elbow position. Upon examination, the following are revealed: cracks in the anus, decreased sphincter tone and its gaping during dysentery, rectal prolapse due to persistent constipation or after an intestinal infection, irritation of the mucous membrane due to pinworm infestation. Digital examination of the rectum and sigmoid colonoscopy can detect polyps, tumors, strictures, fecal stones, ulcerations of the mucous membrane, etc.

Visual inspection of stool is of great importance in assessing the condition of the digestive organs. In infants with intestinal enzymatic dysfunction (simple dyspepsia), dyspeptic stools that look like chopped eggs (liquid, greenish, mixed with white lumps and mucus, acidic reaction) are often observed. Stool is very typical for colitis and dysentery. Bloody stool without admixture of feces against the background of an acutely developed severe general condition can occur in children with intussusception. Discolored stool indicates a delay in the flow of bile into the intestines and is observed in children with hepatitis, blockage or atresia of the bile ducts. Along with determining the quantity, consistency, color, smell and pathological impurities visible to the eye, the characteristics of the stool are supplemented by microscopy data (coprogram) on the presence of leukocytes, erythrocytes, mucus in the stool, as well as helminth eggs and Giardia 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. Of greatest importance is the currently widely used endoscopy, which allows visual assessment of 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 early childhood preschool age are performed under general anesthesia. Ultrasound examination of parenchymal organs, radiography of the biliary tract and gastrointestinal tract (with barium), gastric and duodenal intubation, 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. .

Laboratory and instrumental research methods are of particular importance in the diagnosis of diseases of the pancreas, which, due to its location, is not amenable to direct methods physical research. The size and contours of the gland, the presence of stones in the excretory ducts, and developmental anomalies are detected by relaxation duodenography, as well as retrograde cholangiopancreatography and echopancreatography. Violations of exocrine function observed in cystofibrosis, post-traumatic cysts, biliary atresia, pancreatitis, are accompanied by changes in the level of main enzymes 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 by studying the nature of the glycemic curve.

MINISTRY OF EDUCATION AND SCIENCE OF THE RF

FEDERAL STATE BUDGET

EDUCATIONAL INSTITUTION OF VPO

"VORONEZH STATE PEDAGOGICAL

UNIVERSITY"

Department of Anatomy and Physiology

COURSE WORK

"FOOD HYGIENE IN PRESCHOOL EDUCATIONAL INSTITUTIONS"

Completed:

4th year EHF student,

profile "Biology", OFO

Soboleva Marina

Sergeevna

Checked:

Senior Lecturer

Department of Anatomy and Physiology

Goncharova Inna Georgievna

VORONEZH 2015

Introduction………………………………………………………………………………………...3

Chapter 1. Anatomical and physiological features of the digestive system of preschool children……………………………………………………………………………….4

Chapter 2. Nutrition. Principles of rational nutrition for preschool children. Basic food substances in the diet of preschool children……………….6

2.1. Nutrition. Principles of rational nutrition for preschool children…………………………………………………………………………………………6

2.2. Basic food substances in the diet of preschool children…………………..9

Chapter 3. Sanitary and hygienic requirements for catering in preschool educational institutions…………………………………...13

Conclusion……………………………………………………………………………….19

References……………………………………………………………......20

Introduction

Preschool age (3-7 years) is the most important period when human personality is formed and strong foundations of physical health are laid.

Incomplete maturation child's body determines its instability and greater sensitivity even to minor negative influences of the external environment, which can cause deviations in health. Lack of nutrients and significant physical and mental stress can lead to illness in children, so the principle of balanced nutrition remains one of the most important in preschool age.

From the moment of birth, a child needs hygienic organization of his environment, and especially his nutrition. All this requires the body to receive a sufficient amount of proteins, fats, carbohydrates, minerals and vitamins in a balanced amount.

Purpose: to study the features of food hygiene in preschool educational institutions as a factor in preserving and strengthening the health of preschool children.

- consider the main anatomical and physiological features of the digestive system in preschool children;

Study the principles of rational nutrition for preschool children and the main food substances included in their balanced diet;

To study the sanitary and hygienic requirements for catering in preschool educational institutions.

Chapter 1 Anatomical and physiological features of the digestive system of preschool children

At preschool age, the child has formed milk teeth, which allow him to move from milk nutrition to coarser foods. Salivation increases, the quantity and composition of saliva improves with increasing variety of food. At the age of 5-6 years, the replacement of baby teeth with permanent ones begins.

The size of the stomach gradually increases - by the age of 3 the stomach capacity is 400-600 ml; at the age of 4 to 7 years it increases slowly. By the age of 6-7 years, the stomach takes on the shape characteristic of an adult organism; the length of the esophagus increases.

By this age, the muscles that provide stomach movements and intestinal peristalsis develop. The content of hydrochloric acid increases, which increases the bactericidal properties of gastric juice, which reduces the incidence of gastrointestinal disorders in children, which are caused primarily by dental caries, which ranks first in the structure of morbidity in children 5 - 7 years old.

By 3-4 years of life, the structure of the large intestine is similar to that of adults; stabilization of the intestinal microflora ends in children by the 7th year of life. The functions of the small and large intestines interact and interact. The insufficiency of absorption processes in the small intestine is to some extent compensated by the possibility of absorption in the stomach.

The maturation of the regulation of gastrointestinal motility corresponds to the maturation of the autonomic nervous system and ends by 6-7 years.

In preschool age, the functions of the pancreas and liver intensively develop, but during this period they remain underdeveloped. The activity of pancreatic and duodenal enzymes increases gradually: by 3 years the activity of proteases increases, by 7 years - lipases and amylases.

A feature of metabolic processes in a child’s body is the predominance of anabolic processes over catabolic ones. A growing body requires increased levels of nutrients, especially proteins.

The use of nutritious foods goes in two directions: to ensure the growth and development of the body and to ensure motor activity.

Taking into account the noted features in the functioning of the digestive organs, we can conclude that the nutrition of preschool children should differ from the nutrition of toddlers.

The duodenum in newborns has the shape of a ring. By six months, her descending and ascending sections are determined. The duodenum in children is mobile.

Digestion in the duodenum in children, as in adults, occurs under the influence of pancreatic juice, intestinal juice and bile. The contents of the stomach in the form of food gruel, soaked in acidic gastric juice, partially digested, are moved by movements of the stomach to its pyloric section and pass in portions from the stomach into the duodenum, where the common bile duct and pancreatic duct open. A mixture of secretions from the pancreas, duodenum and liver forms duodenal juice. The activity of duodenal juice enzymes increases with age.

Pancreas. Unlike the stomach, the cellular development of the pancreas ends already in the first months of a child’s life, which explains its special meaning in the early period of development, since the pancreas is the main site of production of digestive enzymes. During the first year of life, the mass of the pancreas increases 3 times, and pancreatic secretion increases 10 times. The growth and development of the pancreas continues up to 11 years.

Pancreatic juice contains:

• ? enzymes: trypsinogen, amylase, maltase, lipase (nuclease is absent in children);
• ? inorganic substances: salts of sodium, potassium, calcium, iron and others, creating an alkaline reaction in the juice.

The mechanism for regulating juice secretion is the same as in adults: humoral (secretin, cholecystokinin) and reflex. The humoral mechanism in children plays the greatest role in the process of regulating digestion.

The liver has insufficient parenchymal differentiation. Liver cells in children are smaller than in adults. Lobulation in the structure of the liver is detected already by the first year of life. Liver is rich in iron.

From the age of eight, the liver has almost the same structure as that of an adult. The liver size in children is relatively larger (4% of body weight) than in adults (2.5%).

The functions of the liver (especially barrier and antitoxic) in the first years of a child’s life are not sufficiently developed, this also applies to storage (in relation to the regulation of the amount of circulating blood) and regulatory (in relation to carbohydrate, fat and water-mineral metabolism) functions.

Bile formation is observed already in a three-month fetus. The intensity of bile formation and bile secretion increases with age. Bile is rich in water, mucin, pigments, and, during the neonatal period, urea, but is poor in bile acids, cholesterol, lecithin and salts, which causes insufficient absorption of fats when feeding with milk. The amount of bile secreted in a child relative to his weight is 4 times greater than in an adult.

The small intestine in children is relatively longer than in adults and has a well-developed mucous membrane with a weak muscle layer. The length of the intestine in an infant is 6 times greater than the length of the body (in an adult - 4.5 times). The most vigorous growth of the small intestine is observed in the first five years, especially between the ages of one and three years due to the transition from dairy foods to a mixed diet.

The mucous membrane is thinner, more delicate, but the folding is well expressed, there are fewer villi, the intestines have a well-developed circulatory and lymphatic system. The villi of the small intestine and the lymphatic apparatus are well developed, the myelination of the nerve plexuses is not complete, the enzymatic power of the digestive glands is insignificant in newborns, but increases with age. The muscle layer and elastic fibers in the intestinal wall are poorly developed. Intestinal juice contains all the enzymes necessary for intestinal digestion, and unlike older children, they are less active, i.e. there is some insufficiency of the secretory apparatus.

Composition of intestinal juice:

• ? mucus - 40-50%, NaHC0 3 - 2%, NaCl - 0.6% (juice reaction is alkaline, ranges from 7.3 to 7.6);
• ? enzymes: erepsin, lipase, amylase, maltase, sucrase, nuclease, enterokinase, alkaline phosphatase (about 22 in total).

Lactase in the small intestine hydrolyzes lactose in cow's milk more easily than in women's milk (with a deficiency of this enzyme, undigested lactose increases the osmotic pressure of the chyme, which leads to diarrhea and dehydration). With the transition to definitive nutrition, the synthesis of maltase and sucrase increases, and lactase production decreases. Proteins in human milk are more fully absorbed in the intestines (90-95%) than in cow's milk (60-70%). When feeding vegetables early, the activity of enterokinase and alkaline phosphatase increases, causing a retention of calcium and magnesium salts in the body. Regulation of intestinal secretion is carried out by reflex and humoral pathways.

In infancy, the low intensity of cavity digestion is compensated by the high activity of membrane digestion. A relatively large portion of the small intestine is involved in nutrient hydrolysis. Its mucous membrane is highly permeable, so not only low molecular weight, but also high molecular weight substances such as immunoglobulins and breast milk hormones are easily absorbed by the child. However, this circumstance, combined with the low level of hydrochloric acid production in the stomach, is the cause of easy development of poisoning when low-quality food enters the gastrointestinal tract.

Thus, the anatomical and physiological characteristics of the children's intestines contribute to the easy occurrence of functional disorders of its motility and secretion.

The fetal large intestine is sterile and colonization by microorganisms occurs on the first day of life. Stabilization of the microflora occurs by the second week. The mucous membrane does not produce cavity enzymes. Digestion is carried out by enzymes coming from the small intestine. The breakdown of chyme occurs due to the activity of the intestinal microbial flora, which has protective antitoxic functions, affects the rate of renewal of epithelial cells, participates in the inactivation of physiologically active substances and enzymes, and promotes the synthesis of vitamins.

There is absolutely no rotting in the intestines of healthy infants in the first months of life, and they do not produce such toxic products as indole, skatole, phenol, etc. In the intestines of older children, both fermentation and putrefaction processes occur simultaneously. Their nature and intensity depends on the characteristics of the child’s food and intestinal bacterial flora.

Between the ages of 10 and 15, intestinal growth occurs again, mainly due to the large intestine.

The motor function of the intestines is low: with breastfeeding, chyme is evacuated in 12-13 hours, with mixed feeding - in 14.5 hours, with artificial feeding - in 16 hours, if the food is vegetable - in 15 hours. This partly explains the tendency to constipation in children. However, the total time for food to pass through the gastrointestinal tract in a child is less than in an adult, which depends on the relative length of the digestive tract, as well as on the type of feeding.

Thus, the functions of the gastrointestinal tract in children are subject to the same physiological laws as in adults. The breakdown of food, which begins in the mouth and stomach, continues in the intestines. Peptones and a certain amount of native (natural, retaining their structure) proteins that have not yet been broken down in the stomach undergo peptic digestion, partly bringing them to the stage of amino acids, partly to the stage of polypeptides of varying complexity. The latter undergo hydrolysis due to the action of erepsin. The effect of trypsin in children is more significant than that of pepsin, since peptic digestion at an early age is of secondary importance.

Gastric, pancreatic and intestinal lipase, in combination with human milk lipase, break down fats into fatty acids and glycerol. The aminolytic action of the pancreas is significantly expanded and supplemented by maltase, lactase, invertase and other enzymes.

In children, as in adults, there is parietal digestion, which is even more active than cavity digestion. In newborns, unlike older children, fermentation rather than putrefaction predominates.

Consequently, the immaturity of the child’s digestive system is expressed in the insufficiency and originality of the enzymatic apparatus in various parts of the gastrointestinal tract. This feature requires a kind of nutrition, especially during the first year of life. The frequency of feeding the child during the day, recording the amount and chemical composition of milk consumed by the child are of great importance.

Digestive system in children: The growth and development of a child is determined by the optimal functioning of the digestive organs.

The functional capabilities of the digestive system at different stages of the body’s development are not the same, which requires a differential approach to feeding and nutrition depending on the age of the child. Formation digestive system in children begins from the 3-4th week of embryonic development.

The oral cavity of a newborn has characteristic features due to the sucking process. U one year old child the size of the oral cavity is relatively small; there are no longer transverse folds on the hard palate; the mucous membrane is tender, dryish, bright red (due to many blood vessels). The tongue is large and almost completely fills the oral cavity; the muscles of the tongue and lips are well developed; on the tongue - all types of taste buds; chewing muscles are well developed.

The salivary glands in a newborn are poorly developed and little saliva is secreted in the first 6-8 weeks of life, but the glands mature quickly and by the end of the 2nd year their structure is similar to the glands of adults. See also Teeth.

The esophagus in newborns and young children has a funnel-shaped shape with an expansion in its cardiac part; elastic and muscle tissue is poorly developed, the mucous membrane has many blood vessels and glands are almost completely absent. The stomach of newborns has a cylindrical or flat shape; when filled with liquid food, it becomes round; As the muscle layers develop and the nature of the food changes, it takes on a retort-like shape.

The capacity of the stomach in newborns is 30-35 ml, by 3 months - up to 100 ml, by one year - up to 200-300 ml. Its fundus and cardiac part are poorly developed in newborns and young children; the pyloric part is formed by 4-6 months, the fundus - by 10-11 months, and the sphincter of the cardiac part - only by 8 years. The gastric mucosa is rich in blood vessels and poor in elastic tissue; has the same glands as in adults.

The muscle layers of the stomach wall are poorly developed, and the pylorus is relatively strongly developed, which predisposes to regurgitation and vomiting in children in the first months of life. The duodenum in newborns and children in the first months of life has a ring-shaped shape, but after 6 months it becomes the same as in adults. Its most intensive growth occurs in the first 5 years.

The shape and size of the small intestine in children change with age. The cecum in newborns and children of the 1st year of life is funnel-shaped, after a year it looks like a blind sac, and by the age of 7 it approaches the shape of adults. In the first 2 years, the vermiform appendix has the shape of a funnel with a wide entrance, through which the contents of the cecum enter it and also freely exit from there; its length in newborns is slightly longer than in adults.

The ascending part of the colon in young children is relatively short, the transverse colon is less mobile due to the short length of the mesentery, and the descending part is relatively long. By the age of 4, the ascending and descending parts become approximately equal in length. The sigmoid colon in the first years of life is relatively long, with a wide mesentery; may have deep bends that contribute to the development of primary constipation, especially in the 1st year of life.

The rectum in newborns and infants is also slightly longer than in adults; the ampullary part is absent. Its mucous and submucosal membranes are poorly fixed and can easily fall out when the child is stressed.

The liver in newborns occupies almost half the volume of the abdominal cavity and accounts for 4.38% of body weight. In the postnatal period, the increase in its mass slows down and lags behind the increase in body weight. In children of the first 6 months of life, the liver protrudes from under the edge of the costal arch at the level of the right nipple line by 2-3 cm, at the age of up to 2 years - by 1.5 cm, 3-7 years - 1.2 cm. diverse functions of digestion and metabolism of substances, is one of the main hematopoietic organs. The lobular structure of the liver is revealed by the age of one year. By the age of 8 years, the histological structure of the liver is identical to that of an adult.

The gallbladder in newborns is spindle-shaped, in older ones it is pear-shaped; up to 5 years, its bottom is projected to the right of the midline 1.5-2 cm below the costal arch. In most children, the location of the gallbladder does not extend beyond the edge of the liver.

The pancreas in newborns is smooth, by 5-6 years it thickens and takes the same shape as in adults; its weight in newborns is from 2 to 3.6 g, length - 4-6 cm, thickness - 1-2 cm; by 2-2.5 years the weight increases to 20 g, by 10-12 - up to 30 g. The pancreas in newborns is located on the border of the abdominal cavity and retroperitoneal space at the level of the XII thoracic - I lumbar vertebrae; its body is covered in front by the stomach, the head lies in the space encircled by the duodenum, the tail part is directed obliquely upward.

In the 2nd year of life, the same topographic relationships of the pancreas with other organs are established as in adults.

Anatomical and physiological features. In young children: 1) thin, tender, dry, easily wounded mucous membrane; 2) a richly vascularized submucosal layer, consisting mainly of loose fiber; 3) underdeveloped elastic and muscle tissue; 4) low secretory function of glandular tissue, separating a small amount of digestive juices with a low content of enzymes. These features make it difficult to digest food if it is not appropriate for the child’s age, reduce the barrier function of the gastrointestinal tract and lead to frequent diseases, create the preconditions for a general systemic reaction to any pathological impact and require very careful and careful care of the mucous membranes.

Oral cavity. ensuring the act of sucking, a relatively small volume of the oral cavity and a large tongue, good development of the muscles of the mouth and cheeks, roller-like duplications of the mucous membrane of the gums and transverse folds on the mucous membrane of the lips, fatty bodies of the cheek (Bishat's lumps). The salivary glands are underdeveloped. at 3-4 months of age, physiological salivation is due to the automatism of swallowing that has not yet been developed.

Esophagus. In young children, the esophagus has a funnel shape. 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.

Stomach. In infants, the stomach is located horizontally, with the pyloric part located near the midline, and the lesser curvature facing posteriorly. When a 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 year 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 - regurgitation (“physiological aerophagia”). Keep children in the first months of life in an upright position for some time. The secretory apparatus of the stomach in children of the first year of life is not sufficiently developed 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 determines the low barrier function of the stomach. It does absolutely necessary implementation dietary requirements in accordance with the age of the child and careful adherence to the sanitary regime during feeding of children (breast toilet, clean hands, proper expression of milk, sterility of nipples and bottles).

In children in the first months of life, intragastric pH reflects a neutral environment or is close to it and only by the end of the first year of life it decreases to 2.0, ensuring maximum pepsin activity.

The main active enzyme of gastric juice is chymosin (rennet enzyme, lab enzyme), which provides the first phase of digestion - milk curdling. Pepsin (in the presence of hydrochloric acid) and lipase continue the hydrolysis of proteins and fats of curdled milk. Nevertheless, its peculiarities in children of the first year of life, which consist in the fact that it can exhibit its activity in a neutral environment, in the absence of bile acids, contribute to the hydrolysis of a certain part of the fats of human milk in the stomach. Maturation of the gastric secretory apparatus occurs earlier and more intensely in children who are bottle-fed. Thus, women's milk stays in the stomach for 2-3 hours, cow's milk - for a longer time (3-4 hours and even up to 5 hours, depending on the buffering properties of the milk).

Pancreas. In a newborn it is small in size (length 5-6 cm, by 10 years - 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 well supplied with blood vessels, intensive growth and differentiation of its structure continues up to 14 years. The organ capsule is less dense than in adults and consists of fine fibrous structures, and therefore compression of the pancreas is rarely observed in children with inflammatory edema of the pancreas. The excretory ducts of the gland are wide, which provides good drainage. albumins, globulins, trace elements and electrolytes, as well as a large set of enzymes necessary for digesting food, including proteolytic (trypsin, chymopsin, elastase, etc.), lipolytic (lipase, phospholipase A and B, etc.) and amylolytic -kih a-i (3-amylase, maltase, lactase, etc.). The secretory activity of the gland reaches the level of secretion of adults by the age of 5.

Liver mass 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 at the end of the first year of life, it is full-blooded, as a result of which it quickly increases in 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 metabolism of indirect bilirubin, released during hemolysis of red blood cells, is not complete, resulting in physiological jaundice.

Gallbladder. In newborns, it 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 composition of the bile of children differs from that 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. the predominance of taurocholic acid over glycocholic acid, as it enhances the bactericidal effect of bile and accelerates the separation of pancreatic juice. Bile emulsifies fats, dissolves fatty acids, and improves peristalsis.

Intestines. In children, the intestine is relatively longer than in adults (in an infant it is 6 times longer than the body length, in adults - 4 times. The cecum and appendix are mobile, the latter is often located atypically, thereby complicating diagnosis during inflammation. The sigmoid colon is relatively larger length than in adults, and in some children it even forms loops, which contributes to the development of habitual constipation. With age, these anatomical features disappear. Due to the weak fixation of the mucous and submucous membranes of the rectum, it may fall out with persistent constipation and tenesmus in weakened children. The mesentery is longer and more easily extensible, due to which torsions, intussusception of intestinal loops, 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. Among the histological features, it should be noted that the villi are well expressed and an abundance of small lymphatic follicles.

The intestinal secretory apparatus is generally formed by the time the child is born, and even in the smallest children the same enzymes are detected in the intestinal juice as in adults (enterokinase, alkaline phosphatase, erepsin, lipase, amylase, maltase, lactase, nuclease), but much less active. The large intestine secretes only mucus. Under the influence of intestinal enzymes, mainly the pancreas, the breakdown of proteins, fats and carbohydrates occurs. The process of fat digestion is especially intense due to the low activity of lipolytic enzymes.

Vitamins A, D, C, and group B are absorbed in the small intestine, especially in its proximal sections.

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, microorganisms and other pathogenic factors. The most easily digestible components of human milk are the proteins and fats of which are partially absorbed undigested in newborns. The motor (motor) function of the intestine is carried out in children very energetically due to pendulum-like movements that mix food, and peristaltic movements that move food to the exit. In infants, defecation occurs reflexively, in the first 2 weeks of life up to 3-6 times a day, then less often, per year, as a voluntary act. In the first 2-3 days after birth, the baby secretes meconium (original feces) of a greenish-black color. It consists of bile, epithelial cells, mucus, enzymes, and swallowed amniotic fluid. The stool of healthy newborns who are breastfed has a mushy consistency, golden-yellow color, and a sour smell. In older children, stools are formed, 1-2 times a day.

Microflora. During intrauterine development, the fetal intestine is sterile. It is colonized by microorganisms first during the passage of the mother's birth canal, then through the mouth when children come into contact with surrounding objects. According to modern concepts, normal intestinal flora performs three main functions: 1) creation of an immunological barrier; 2) final digestion of food debris and digestive enzymes; 3) synthesis of vitamins and enzymes. The normal composition of intestinal microflora (eubiosis) is easily disrupted under the influence of infection, poor diet, as well as irrational use of antibacterial agents and other drugs, leading to a state of intestinal dysbiosis.