What anatomical and physiological features of the respiratory system in children should you know first of all? Anatomical and physiological features of the respiratory system in children. Clinical significance

Fetal breathing. In intrauterine life, the fetus receives 0 2 and removes CO 2 exclusively through placental circulation. However, the large thickness of the placental membrane (10-15 times thicker than the pulmonary membrane) does not allow equalization of partial gas tensions on both sides. The fetus develops rhythmic, respiratory movements with a frequency of 38-70 per minute. These breathing movements amount to a slight expansion of the chest, which is followed by a longer contraction and an even longer pause. In this case, the lungs do not expand, remain collapsed, the alveoli and bronchi are filled with fluid, which is secreted by alveolocytes. Only a slight negative pressure arises in the interpleural fissure as a result of the separation of the outer (parietal) layer of the pleura and an increase in its volume. Respiratory movements of the fetus occur with a closed glottis, and therefore in Airways amniotic fluid does not enter.

Meaning breathing movements fetus: 1) they help increase the speed of blood movement through the vessels and its flow to the heart, and this improves blood supply to the fetus; 2) the respiratory movements of the fetus contribute to the development of the lungs and respiratory muscles, i.e. those structures that the body will need after its birth.

Features of gas transport by blood. The oxygen tension (P0 2) in the oxygenated blood of the umbilical vein is low (30-50 mm Hg), the content of oxyhemoglobin (65-80%) and oxygen (10-150 ml/l of blood) is reduced, and therefore it is still less in the vessels of the heart, brain and other organs. However, the fetus has fetal hemoglobin (HbF), which has a high affinity for 02, which improves the oxygen supply to cells due to the dissociation of oxyhemoglobin at more low values partial gas tension in tissues. By the end of pregnancy, the HbF content decreases to 40%. Voltage carbon dioxide(PC0 2) in arterial blood fetus (35-45 mm Hg) is low due to hyperventilation of pregnant women. Red blood cells lack the enzyme carbonic anhydrase, as a result of which up to 42% of carbon dioxide, which can combine with bicarbonates, is excluded from transport and gas exchange. Mainly physical dissolved CO2 is transported through the placental membrane. By the end of pregnancy, the content of CO 2 in the fetal blood increases to 600 ml/l. Despite these features of gas transport, fetal tissues have an adequate supply of oxygen due to the following factors: tissue blood flow is approximately 2 times greater than in adults; anaerobic oxidative processes predominate over aerobic ones; The energy costs of the fetus are minimal.

Breathing of a newborn. From the moment the baby is born, even before the umbilical cord is clamped, pulmonary breathing begins. The lungs expand completely after the first 2-3 breathing movements.

The causes of the first breath are:

• 1) excess accumulation CO 2 and H + and depletion of 0 2 blood after cessation of placental circulation, which stimulates central chemoreceptors;
• 2) changes in living conditions, a particularly powerful factor is irritation of skin receptors (mechano- and thermoceptors) and increasing afferent impulses from vestibular, muscle and tendon receptors;
• 3) the pressure difference in the interpleural gap and in the respiratory tract, which during the first breath can reach 70 mm of water column (10-15 times more than during subsequent quiet breathing).

In addition, as a result of irritation of the receptors located in the nostril area by the amniotic fluid (diver's reflex), inhibition stops respiratory center. The inspiratory muscles (diaphragm) are excited, which causes an increase in volume chest cavity and a decrease in intrapleural pressure. The inhalation volume turns out to be greater than the exhalation volume, which leads to the formation of an alveolar air supply (functional residual capacity). Exhalation in the first days of life is carried out actively with the participation of expiratory muscles (exhalation muscles).

When taking the first breath, significant elasticity is overcome lung tissue, caused by the force of surface tension of collapsed alveoli. During the first breath, energy is expended 10-15 times more than in subsequent breaths. To stretch the lungs of children who have not yet breathed, the air flow pressure must be approximately 3 times greater than in children who have switched to spontaneous breathing.

The first breath is facilitated by a surfactant, which in the form of a thin film covers the inner surface of the alveoli. Surfactant reduces surface tension forces and the work required for ventilation of the lungs, and also maintains the alveoli in a straightened state, protecting them from sticking together. This substance begins to be synthesized in the 6th month of intrauterine life. When the alveoli are filled with air, it spreads in a monomolecular layer over the surface of the alveoli. In non-viable newborns who died from alveolar adhesion, a lack of surfactant was found.

The pressure in the interpleural gap of a newborn during exhalation is equal to atmospheric pressure; during inhalation it decreases and becomes negative (in adults it is negative both during inhalation and during exhalation).

According to generalized data, in newborns the number of respiratory movements per minute is 40-60, the minute volume of breathing is 600-700 ml, which is 170-200 ml/min/kg.

With the beginning pulmonary respiration Due to the expansion of the lungs, acceleration of blood flow and reduction of the vascular bed in the pulmonary circulatory system, blood circulation through the pulmonary circulation changes. An open arterial (botal) duct in the first days, and sometimes weeks, can maintain hypoxia by directing part of the blood from pulmonary artery into the aorta, bypassing the small circle.

Features of frequency, depth, rhythm and type of breathing in children. Children's breathing is frequent and shallow. This is due to the fact that the work spent on breathing, compared to adults, is greater, since, firstly, diaphragmatic breathing, since the ribs are located horizontally, perpendicular to the spinal column, which limits the excursion of the chest. This type of breathing remains dominant in children up to 3-7 years of age. It requires overcoming the resistance of the abdominal organs (children have a relatively large liver and frequent bloating intestines); secondly, in children the elasticity of the lung tissue is high (low extensibility of the lungs due to the small number of elastic fibers) and significant bronchial resistance due to the narrowness of the upper respiratory tract. In addition, the alveoli are smaller, poorly differentiated, and limited in number (air/tissue surface area is only 3 m2, compared to 75 m2 in adults).

The respiratory rate in children of different ages is presented in table. 6.1.

Respiratory rate in children of different ages

Table 6.1

The respiratory rate in children changes significantly during the day, and also changes significantly more than in adults under the influence of various influences(mental excitement, exercise stress, increased body and environmental temperature). This is explained by the slight excitability of the respiratory center in children.

Up to 8 years of age, the breathing rate in boys is slightly higher than in girls. By puberty, the respiratory rate in girls becomes higher, and this ratio persists throughout life.

Breathing rhythm. In newborns and infants, breathing is irregular. Deep breathing is replaced by shallow breathing. The pauses between inhalation and exhalation are uneven. The duration of inhalation and exhalation in children is shorter than in adults: inhalation is 0.5-0.6 s (in adults 0.98-2.82 s), and exhalation is 0.7-1 s (in adults 1.62 -5.75 s). From the moment of birth, the same relationship between inhalation and exhalation as in adults is established: inhalation is shorter than exhalation.

Types of breathing. In a newborn, until the second half of the first year of life, the diaphragmatic type of breathing predominates, mainly due to contraction of the diaphragm muscles. Chest breathing is difficult because the chest has a pyramidal shape, the upper ribs, the manubrium of the sternum, the collarbone and the entire shoulder girdle are located high, the ribs lie almost horizontally, and the respiratory muscles of the chest are weak. From the moment the child begins to walk and increasingly takes a vertical position, breathing becomes abdominal. From 3-7 years due to muscle development shoulder girdle The chest type of breathing begins to predominate over the diaphragmatic one. Gender differences in the type of breathing begin to emerge from 7-8 years of age and end by 14-17 years. By this time, girls have developed a chest, and boys - abdominal type breathing.

Lung volumes in children. In a newborn baby, the volume of the lungs increases slightly during inspiration. The tidal volume is only 15-20 ml. During this period, the body is supplied with oxygen by increasing the respiratory rate. With age, along with a decrease in respiratory rate, tidal volume increases (Table 6.2). Minute volume of respiration (MVR) also increases with age (Table 6.3), amounting to 630-650 ml/min in newborns, and 6100-6200 ml/min in adults. At the same time, the relative volume of respiration (the ratio of MVR to body weight) in children is approximately 2 times greater than in adults (in newborns the relative volume of respiration is about 192, in adults it is 96 ml/min/kg). This is explained by the high level of metabolism and 02 consumption in children compared to adults. Thus, the oxygen requirement is (in ml/min/kg body weight): in newborns - 8-8.5; at 1-2 years - 7.5-8.5; at 6-7 years old - 8-8.5; at 10-11 years old -6.2-6.4; at 13-15 years old - 5.2-5.5 and in adults - 4.5.

Vital capacity of the lungs in children of different ages (V.A. Doskin et al., 1997)

Table 6.2

The vital capacity of the lungs is determined in children starting from 4-5 years old, since the active and conscious participation of the child himself is required (Table 6.2). The so-called vital capacity of a cry is determined in a newborn. It is believed that during a strong cry, the volume of exhaled air is equal to vital capacity. In the first minutes after birth it is 56-110 ml.

Age indicators of minute volume of respiration (V.A. Doskin et al., 1997)

Table 6.3

An increase in absolute indicators of all respiratory volumes is associated with the development of the lungs in ontogenesis, an increase in the number and volume of alveoli up to 7-8 years of age, a decrease in aerodynamic resistance to breathing due to an increase in the lumen of the airways, a decrease in elastic resistance to breathing due to an increase in the proportion of elastic fibers in the lungs relative to collagen , increasing the strength of the respiratory muscles. Therefore, the energy cost of breathing decreases (Table 6.3).

By the end of the 3rd - at the beginning of the 4th week of embryonic development, a protrusion of the wall of the foregut appears, from which the larynx, trachea, bronchi and lungs are formed. This protrusion grows rapidly, a flask-shaped expansion appears at the caudal end, which at the 4th week is divided into right and left parts (future right and left lungs). Each part is further divided into smaller branches (future shares). The resulting protrusions grow into the surrounding mesenchyme, continuing to divide and again forming spherical extensions at their ends - rudiments of bronchi of increasingly smaller caliber. At the 6th week they form lobar bronchi, on the 8th-10th - segmental bronchi. Formation begins from the 16th week respiratory bronchioles. Thus, by the 16th week, the bronchial tree is mainly formed. This is the so-called glandular stage of lung development. From the 16th week, the formation of a lumen in the bronchi begins (recanalization stage), and from the 24th - the formation of future acini (alveolar stage), does not end at birth; the formation of alveoli continues in the postnatal period. By the time of birth, there are about 70 million primary alveoli in the fetal lungs. Formation of the cartilaginous framework of the trachea and bronchi begins from the 10th week, from the 13th week the formation of glands in the bronchi begins, promoting the formation of a lumen. Blood vessels are formed from mesenchyme in the 20th week, and motor neurons - from the 15th week. Vascularization of the lungs occurs especially quickly at 26-28 weeks. Lymphatic vessels are formed in the 9-10th week, initially in the area of ​​the root of the lung. By birth they are fully formed.

Formation of acini, which began at the 24th week does not end at birth, and their formation continues in the postnatal period.

By the birth of a child, the respiratory tract (larynx, trachea, bronchi and acini) is filled with fluid, which is a secretion product of respiratory tract cells. It contains a small amount of protein and has a low viscosity, which facilitates its rapid absorption immediately after birth, from the moment breathing is established.

Surfactant, a layer of which (0.1-0.3 µm) covers the alveoli, begins to be synthesized at the end intrauterine development. Methyl and phosphocholine transferases take part in the synthesis of surfactant. Methyltransferase begins to form from the 22-24th week of intrauterine development, and its activity progressively increases towards birth. Phosphocholine transferase usually matures only by the 35th week of gestation. A deficiency of the surfactant system underlies respiratory distress syndrome, which is more often observed in premature infants, clinically manifesting as severe respiratory failure.

The information presented on embryogenesis suggests that congenital tracheal stenosis and lung agenesis are the result of developmental disorders at very early stages of embryogenesis. Congenital lung cysts are also a consequence of malformation of the bronchi and accumulation of secretions in the alveoli.

The part of the foregut from which the lungs originate further develops into the esophagus. If the correct process of embryogenesis is disrupted, a communication remains between the primary intestinal tube (esophagus) and the grooved protrusion (trachea) - esophageal-tracheal fistulas. Although this pathological condition It is rare in newborns; however, if it is present, their fate depends on the time of diagnosis and the speed of providing the necessary medical care. A newborn with such a developmental defect looks quite normal in the first hours and breathes freely. However, at the first attempt at feeding, asphyxia occurs due to milk entering the trachea from the esophagus - the child turns blue, a large number of wheezes are heard in the lungs, and an infection quickly develops. Treatment of such a malformation is only surgical and should be carried out immediately after diagnosis. A delay in treatment causes severe, sometimes irreversible, organic changes in the lung tissue due to the constant entry of food and gastric contents into the trachea.

It is customary to distinguish upper(nose, throat), average(larynx, trachea, lobar, segmental bronchi) and lower(bronchioles and alveoli) respiratory tract. Knowledge of the structure and function of various parts of the respiratory organs is of great importance for understanding the characteristics of respiratory organ damage in children.

Upper respiratory tract.Nose in a newborn it is relatively small, its cavities are poorly developed, and the nasal passages are narrow (up to 1 mm). The lower nasal meatus is absent. The cartilage of the nose is very soft. The nasal mucosa is delicate and rich in blood and lymphatic vessels. By the age of 4, the lower nasal passage is formed. As the facial bones (upper jaw) enlarge and teeth erupt, the length and width of the nasal passages increase. In newborns, the cavernous part of the submucosal tissue of the nose is underdeveloped, which develops only by 8-9 years. This explains the relative rarity of nosebleeds in children 1 year of age. Due to the insufficient development of cavernous tissue in young children, the inhaled air is poorly warmed; therefore, children cannot be taken outside at temperatures below -10 ° C. A wide nasolacrimal duct with underdeveloped valves contributes to the transfer of inflammation from the nose to the mucous membrane of the eyes. Due to the narrowness of the nasal passages and the abundant blood supply to the mucous membrane, the appearance of even slight inflammation of the nasal mucosa causes difficulty breathing through the nose in young children. Breathing through the mouth in children in the first half of life is almost impossible, since the large tongue pushes the epiglottis backward.

Although paranasal sinuses The nose begins to form in the prenatal period; by birth they are not sufficiently developed (Table 1).

Table 1

Development of the paranasal sinuses

These features explain the rarity of diseases such as sinusitis, frontal sinusitis, ethmoiditis, polysinusitis (disease of all sinuses) in early childhood. When breathing through the nose, air passes with greater resistance than when breathing through the mouth, therefore, when breathing through the nose, the work of the respiratory muscles increases and breathing becomes deeper. Atmospheric air passing through the nose is warmed, moistened and purified. The lower the external temperature, the greater the air warming. For example, the air temperature when passing through the nose at the level of the larynx is only 2...3 ° C lower than body temperature. In the nose, the inhaled air is purified, and foreign bodies larger than 5-6 microns in size are captured in the nasal cavity (more fine particles penetrate into the underlying sections). 0.5-1 liters of mucus per day are secreted into the nasal cavity, which moves in the posterior 2/3 of the nasal cavity at a speed of 8-10 mm/min, and in the anterior third - 1-2 mm/min. Every 10 minutes, a new layer of mucus passes through, which contains bactericidal substances (lysozyme, complement, etc.), secretory immunoglobulin A.

Pharynx in a newborn it is narrow and small. The lymphopharyngeal ring is poorly developed. Both palatine tonsils in newborns do not normally protrude from behind the arches soft palate into the cavity of the pharynx. In the second year of life, hyperplasia of the lymphoid tissue is observed, and the tonsils protrude from the anterior arches. The crypts in the tonsils are poorly developed, so tonsillitis in children under one year of age, although they occur, is less common than in older children. By 4-10 years, the tonsils are already well developed and can easily hypertrophy. Tonsils are similar in structure and function to lymph nodes.

Tonsils are like a filter for microorganisms, but with frequent inflammatory processes a focus of chronic infection can form in them. At the same time, they gradually increase in size, hypertrophy - chronic tonsillitis develops, which can occur with general intoxication and cause sensitization of the body.

The nasopharyngeal tonsils can enlarge - these are the so-called adenoid vegetations, which disrupt normal nasal breathing, and also, being a significant receptor field, can cause allergization, intoxication of the body, etc. Children with adenoids are inattentive, which affects their studies at school. In addition, adenoids contribute to the formation of malocclusion.

Among the lesions of the upper respiratory tract in children, rhinitis and tonsillitis are most often observed.

Middle and lower respiratory tract.Larynx before the birth of a child, it has a funnel-shaped shape, its cartilages are tender and pliable. The glottis is narrow and located high - at level IV cervical vertebra(in adults - at the level of the VII cervical vertebra). The cross-sectional area of ​​the airway under the vocal folds is on average 25 mm, and the length of the vocal folds is 4-4.5 mm. The mucous membrane is delicate, rich in blood and lymphatic vessels. Elastic tissue is poorly developed. Up to 3 years of age, the shape of the larynx is the same in boys and girls. After 3 years, the angle of connection of the thyroid plates in boys becomes sharper, which becomes especially noticeable by the age of 7; By the age of 10, boys have a larynx similar to that of an adult man.

Glottis remains narrow until 6-7 years. The true vocal folds of young children are shorter than those of older children (this is why they have a high voice); From the age of 12, boys' vocal folds become longer than girls'. The peculiarity of the structure of the larynx in young children also explains the frequency of its damage (laryngitis), and they are often accompanied by difficulty breathing - croup.

Trachea almost completely formed by the time the baby is born. It has a funnel shape. Its upper edge is located at the level of the IV cervical (in an adult at the VII level) vertebra. The bifurcation of the trachea lies higher than in an adult. It can be roughly defined as the intersection of lines drawn from spinae scapulae to the spine. The mucous membrane of the trachea is delicate and rich in blood vessels. The elastic tissue is poorly developed, and its cartilaginous frame is soft and easily narrows the lumen. With age, the trachea increases both in length and in diameter, however, compared with body growth, the rate of growth of the trachea lags behind, and only from puberty does the increase in its size accelerate.

The diameter of the trachea changes during the respiratory cycle. The lumen of the trachea changes especially significantly during coughing - the longitudinal and transverse dimensions decrease by 1/3. There are many glands in the mucous membrane of the trachea - approximately one gland per 1 mm 2 of surface. Thanks to the secretion of glands, the surface of the trachea is covered with a layer of mucus 5 microns thick, the speed of mucus movement is 10-15 mm/min, which is ensured by the movement of cilia of the ciliated epithelium (10-35 cilia per 1 micron 2).

The structural features of the trachea in children determine its frequent isolated lesions (tracheitis), in the form of a combination with lesions of the larynx (laryngotracheitis) or bronchi (tracheobronchitis).

Bronchi by the time of birth they are quite well formed. The mucous membrane has a rich blood supply and is covered with a thin layer of mucus, which moves at a speed of 0.25-1 cm/min. In the bronchioles, the movement of mucus is slower (0.15-0.3 cm/min). The right bronchus is like a continuation of the trachea; it is shorter and somewhat wider than the left.

Muscle and elastic fibers in children of the first year of life are still poorly developed. With age, both the length and lumen of the bronchi increase. The bronchi grow especially quickly in the first year of life, then their growth slows down. At the onset of puberty, their growth rate increases again. By the age of 12-13 years, the length of the main bronchi doubles; with age, the resistance to bronchi collapse increases. In children acute bronchitis is a manifestation of respiratory viral infection. Asthmatic bronchitis with respiratory allergies is less common. The tenderness of the structure of the bronchial mucosa and the narrowness of their lumen also explain the relatively frequent occurrence in young children. bronchiolitis with complete or partial obstruction syndrome.

Lung weight at birth equal to 50-60 g, which is 1/50 of body weight. Subsequently, it increases rapidly, and is especially intense during the first 2 months of life and during puberty. It doubles by 6 months, triples by one year of life, increases almost 6 times by 4-5 years, 10 times by 12-13 years, and 20 times by 20 years.

In newborns, the lung tissue is less airy and is characterized by the abundant development of blood vessels and loose connective tissue in the septa of the acini. Elastic tissue is underdeveloped, which explains the relatively easy occurrence of emphysema in various pulmonary diseases. Thus, the ratio of elastin and collagen in the lungs (dry tissue) in children under 8 months is 1: 3.8, while in an adult it is 1: 1.7. By the birth of a child, the respiratory part of the lungs itself (acinus, where gas exchange occurs between air and blood) is not sufficiently developed.

Alveoli begin to form from the 4-6th week of life, and their number increases very quickly during the first year, increasing until 8 years, after which the lungs increase due to the linear size of the alveoli.

According to the increase in the number of alveoli, the respiratory surface also increases, especially significantly during the first year.

This corresponds to the greater oxygen demand of children. By birth, the lumen of the terminal bronchioles is less than 0.1 mm, by 2 years it doubles, by 4 years it triples, and by 18 years it increases 5 times.

The narrowness of the bronchioles explains the frequent occurrence of pulmonary atelectasis in young children. A.I. Strukov identified 4 periods in the development of the lungs in children.

In the first period (from birth to 2 years) There is a particularly intensive development of the alveoli.

In period II (from 2 to 5 years) Elastic tissue, muscular bronchi with peribronchial and lymphoid tissue included in it develop intensively. This probably explains the increase in the number of cases of pneumonia with a protracted course and the beginning of the formation of chronic pneumonia in children of pre-preschool age.

INIIIperiod (5-7 years) the final maturation of the acinus structure occurs, which explains the more benign course of pneumonia at preschool children and school age.

In the IV period (7-12 years) there is an increase in the mass of mature lung tissue.

As you know, the right lung consists of three lobes: upper, middle and lower, and the left lung consists of two: upper and lower. Middle share right lung corresponds to the lingular lobe in the left lung. The development of individual lobes of the lung is uneven. In children of the 1st year of life, the upper lobe of the left lung is less developed, and the upper and middle lobes of the right lung are almost the same size. Only by the age of 2 years do the sizes of the individual lobes of the lung correspond to each other, as in adults.

Along with dividing the lungs into lobes in recent years great importance acquires knowledge of the segmental structure of the lungs, since it explains the features of the localization of lesions and is always taken into account when surgical interventions on the lungs.

As mentioned, the formation of the structure of the lungs occurs depending on the development of the bronchi. After dividing the trachea into the right and left bronchi, each of them is divided into lobes, which approach each lobe of the lung. Then the lobar bronchi are divided into segmental bronchi. Each segment has the shape of a cone or pyramid with the apex directed towards the root of the lung.

The anatomical and functional features of the segment are determined by the presence of independent ventilation, the terminal artery and intersegmental partitions made of elastic connective tissue. The segmental bronchus with corresponding blood vessels occupies a certain area in the lung lobe. The segmental structure of the lungs is already well expressed in newborns. There are 10 segments in the right lung, and 9 in the left lung (Fig. 1).

Rice. 1. Segmental structure of the lungs

Upper left and right lobes are divided into 3 segments: apical (1), superoposterior(2) and upper anterior(3). Sometimes another additional segment is mentioned - axillary, which is not considered independent.

Middle right lobe is divided into 2 segments: interior(4), located medially, and outer(5), located laterally. In the left lung the middle beat corresponds to reed, also consisting of 2 segments - superior lingual(4) and inferior lingual (5).

The lower lobe of the right lung is divided into 5 segments: basal-apical (6), basal-medial (7), basal-anterior (8), basal-lateral (9) and basal-posterior (10).

The lower lobe of the left lung is divided into 4 segments: basal-apical (6), basal-anterior (8), basal-lateral (9) and basal-posterior (10).

In children, the pneumonic process is most often localized in certain segments, which is associated with the characteristics of their aeration, the drainage function of their bronchi, the evacuation of secretions from them and the possibility of infection. Most often, pneumonia is localized in the lower lobe, namely in the basal-apical segment (6). This segment is to a certain extent isolated from the other segments of the lower lobe. Its segmental bronchus arises above the other segmental bronchi and runs at a right angle straight back. This creates conditions for poor drainage, since young children usually lie down for a long time. Along with damage to the 6th segment, pneumonia is also often localized in the superoposterior (2) segment of the upper lobe and the basal-posterior (10) segment of the lower lobe. This is precisely what explains common form so-called paravertebral pneumonia. A special place is occupied by damage to the middle lobe - with this localization, pneumonia is acute. There is even a term "middle lobe syndrome".

The midlateral (4) and midanterior (5) segmental bronchi are located in the area of ​​the bronchopulmonary lymph nodes; they have a relatively narrow lumen, considerable length and extend at a right angle. As a result, the bronchi are easily compressed by the enlarged lymph nodes, which suddenly leads to the shutdown of a significant respiratory surface and causes the development of severe respiratory failure.

The formation of the tracheopulmonary system begins at the 3-4th week of embryonic development. Already by the 5th-6th week of embryo development, second-order branches appear and the formation of three lobes of the right lung and two lobes of the left lung is predetermined. During this period, the trunk of the pulmonary artery is formed, growing into the lungs along the primary bronchi.

In the embryo, at the 6-8th week of development, the main arterial and venous collectors of the lungs are formed. Growth occurs within 3 months bronchial tree, segmental and subsegmental bronchi appear.

During the 11-12th week of development, areas of lung tissue are already present. They, together with the segmental bronchi, arteries and veins, form the embryonic segments of the lungs.

Rapid growth is observed between 4 and 6 months vascular system lungs.

In fetuses at 7 months, the lung tissue acquires the features of a porous canal structure; the future air spaces are filled with fluid, which is secreted by the cells lining the bronchi.

At 8-9 months of the intrauterine period, further development of the functional units of the lungs occurs.

The birth of a child requires the immediate functioning of the lungs, during which time significant changes occur with the onset of breathing. airways, especially the respiratory part of the lungs. The formation of the respiratory surface in individual parts of the lungs occurs unevenly. For the administration breathing apparatus lungs great value have the condition and readiness of the surfactant film lining the lung surface. Violation of the surface tension of the surfactant system leads to serious illnesses in young children.

In the first months of life, the child maintains the ratio of the length and width of the airways, like a fetus, when the trachea and bronchi are shorter and wider than in adults, and the small bronchi are narrower.

The pleura covering the lungs in a newborn baby is thicker, looser, contains villi and outgrowths, especially in the interlobar grooves. Pathological foci appear in these areas. Before the birth of a child, the lungs are prepared to perform the respiratory function, but individual components are in the development stage, the formation and maturation of the alveoli is rapidly proceeding, the small lumen of the muscular arteries is being reconstructed and the barrier function is being eliminated.

After three months of age, period II is distinguished.

1. period of intensive growth of the pulmonary lobes (from 3 months to 3 years).
2. final differentiation of all bronchopulmonary system(from 3 to 7 years).

Intensive growth of the trachea and bronchi occurs in the 1st–2nd year of life, which slows down in subsequent years, and the small bronchi grow intensively, and the branching angles of the bronchi also increase. The diameter of the alveoli increases, and the respiratory surface of the lungs doubles with age. In children under 8 months, the diameter of the alveoli is 0.06 mm, in 2 years - 0.12 mm, in 6 years - 0.2 mm, in 12 years - 0.25 mm.

In the first years of life, growth and differentiation of lung tissue elements and blood vessels occur. The ratio of the volumes of shares in individual segments is equalized. Already at 6-7 years of age, the lungs are a fully formed organ and are indistinguishable from the lungs of adults.

Features of the child's respiratory tract

The respiratory tract is divided into upper, which includes the nose, paranasal sinuses, pharynx, Eustachian tubes, and lower, which includes the larynx, trachea, bronchi.

The main function of breathing is to conduct air into the lungs, cleanse it of dust particles, protect the lungs from harmful effects bacteria, viruses, foreign particles. In addition, the airways warm and humidify the inhaled air.

The lungs are represented by small sacs that contain air. They connect with each other. The main function of the lungs is to absorb oxygen from the atmospheric air and release gases into the atmosphere, primarily acid coal.

Breathing mechanism. When inhaling, the diaphragm and chest muscles contract. Exhalation in older age occurs passively under the influence of elastic traction of the lungs. With bronchial obstruction, emphysema, and also in newborns, active inhalation occurs.

Normally, breathing is established at a frequency at which the volume of breathing is performed due to the minimum energy expenditure of the respiratory muscles. In newborn children, the respiratory rate is 30-40, in adults - 16-20 per minute.

The main carrier of oxygen is hemoglobin. In the pulmonary capillaries, oxygen binds to hemoglobin, forming oxyhemoglobin. In newborns, fetal hemoglobin predominates. On the first day of life, it is contained in the body about 70%, by the end of the 2nd week - 50%. Fetal hemoglobin has the ability to easily bind oxygen and difficult to release it to tissues. This helps the child in the presence of oxygen starvation.

Transport of carbon dioxide occurs in dissolved form; blood saturation with oxygen affects the content of carbon dioxide.

The respiratory function is closely related to the pulmonary circulation. This is a complex process.

During breathing, autoregulation is noted. When the lung stretches during inhalation, the inhalation center is inhibited, and exhalation is stimulated during exhalation. Deep breathing or forced inflation of the lungs leads to a reflex expansion of the bronchi and increases the tone of the respiratory muscles. When the lungs collapse and are compressed, the bronchi become narrowed.

The medulla oblongata contains the respiratory center, from where commands are sent to the respiratory muscles. The bronchi lengthen when you inhale, and shorten and narrow when you exhale.

The relationship between the functions of breathing and blood circulation appears from the moment the lungs expand during the first breath of a newborn, when both the alveoli and blood vessels expand.

With respiratory diseases in children, respiratory dysfunction and respiratory failure may occur.

Features of the structure of a child's nose

In young children, the nasal passages are short, the nose is flattened due to an insufficiently developed facial skeleton. The nasal passages are narrower, the conchae are thickened. The nasal passages are fully formed only by the age of 4 years. The nasal cavity is relatively small in size. The mucous membrane is very loose and well supplied with blood vessels. The inflammatory process leads to the development of edema and, as a result, a reduction in the lumen of the nasal passages. Mucus often stagnates in the nasal passages. It can dry out, forming crusts.

When the nasal passages close, shortness of breath may occur; during this period, the child cannot suckle at the breast, becomes anxious, abandons the breast, and remains hungry. Children, due to difficulty in nasal breathing, begin to breathe through their mouths, their warming of the incoming air is disrupted and their susceptibility to colds increases.

If nasal breathing is impaired, there is a lack of discrimination of odors. This leads to loss of appetite, as well as a violation of the idea of external environment. Breathing through the nose is physiological, breathing through the mouth is a sign of nasal disease.

Accessory cavities nose The paranasal cavities, or sinuses, as they are called, are limited spaces filled with air. The maxillary (maxillary) sinuses are formed by the age of 7. Ethmoidal - by the age of 12, the frontal is fully formed by the age of 19.

Features of the nasolacrimal duct. The nasolacrimal duct is shorter than in adults, its valves are not sufficiently developed, and the outlet is located close to the corner of the eyelids. Due to these features, the infection quickly spreads from the nose to the conjunctival sac.

Features of the pharynxchild

The pharynx in young children is relatively wide, the palatine tonsils are poorly developed, which explains the rare cases of sore throat in the first year of life. The tonsils are fully developed by the age of 4-5 years. By the end of the first year of life, almond tissue hyperplasias. But her barrier function at this age is very low. Overgrown almond tissue can be susceptible to infection, which is why diseases such as tonsillitis and adenoiditis occur.

The Eustachian tubes open into the nasopharynx and connect it to the middle ear. If an infection travels from the nasopharynx to the middle ear, otitis media occurs.

Features of the larynxchild

Larynx in children - funnel-shaped, is a continuation of the pharynx. In children, it is located higher than in adults, and has a narrowing in the area of ​​the cricoid cartilage, where the subglottic space is located. The glottis is formed by the vocal cords. They are short and thin, this is responsible for the child’s high, sonorous voice. The diameter of the larynx in a newborn in the area of ​​the subglottic space is 4 mm, at 5-7 years old - 6-7 mm, by 14 years old - 1 cm. Features of the larynx in children are: its narrow lumen, many nerve receptors, easily occurring swelling of the submucosal layer, which can lead to severe disorders breathing.

The thyroid cartilages form a more acute angle in boys over 3 years of age; from the age of 10, a typical male larynx is formed.

Features of the tracheachild

The trachea is a continuation of the larynx. It is wide and short, the tracheal frame consists of 14-16 cartilaginous rings, which are connected by a fibrous membrane instead of an elastic end plate in adults. The presence of a large number of muscle fibers in the membrane contributes to changes in its lumen.

Anatomically, the trachea of ​​a newborn is located at the level of the IV cervical vertebra, and in an adult - at the level of the VI-VII cervical vertebra. In children, it gradually descends, as does its bifurcation, which is located on the newborn's level III thoracic vertebra, in children 12 years old - at the level of the V-VI thoracic vertebra.

In progress physiological breathing the lumen of the trachea changes. During coughing, it decreases by 1/3 of its transverse and longitudinal dimensions. The mucous membrane of the trachea is rich in glands that secrete a secretion that covers the surface of the trachea with a layer 5 microns thick.

The ciliated epithelium promotes the movement of mucus at a speed of 10-15 mm/min from the inside to the outside.

Features of the trachea in children contribute to the development of its inflammation - tracheitis, which is accompanied by a rough, low-timbre cough, reminiscent of a cough “like in a barrel”.

Features of the child's bronchial tree

The bronchi in children are formed at birth. Their mucous membrane is richly supplied with blood vessels and is covered with a layer of mucus, which moves at a speed of 0.25-1 cm/min. A feature of the bronchi in children is that they are elastic and muscle fibers poorly developed.

The bronchial tree branches to the bronchi of the 21st order. With age, the number of branches and their distribution remain constant. The size of the bronchi changes rapidly in the first year of life and during puberty. They are based on cartilaginous semirings in early childhood. Bronchial cartilage is very elastic, pliable, soft and easily displaced. The right bronchus is wider than the left and is a continuation of the trachea, so foreign bodies are more often found in it.

After the birth of a child, a columnar epithelium with a ciliated apparatus is formed in the bronchi. With hyperemia of the bronchi and their swelling, their lumen sharply decreases (up to its complete closure).

Underdevelopment of the respiratory muscles contributes to a weak cough impulse in small child, which can lead to blockage of small bronchi with mucus, and this, in turn, leads to infection of the lung tissue and disruption of the cleansing drainage function of the bronchi.

With age, as the bronchi grow, wide lumens of the bronchi appear, and the bronchial glands produce less viscous secretions. acute diseases bronchopulmonary system compared to younger children.

Features of the lungsin children

The lungs in children, as in adults, are divided into lobes, and lobes into segments. The lungs have a lobular structure, the segments in the lungs are separated from each other by narrow grooves and partitions of connective tissue. The main structural unit is the alveoli. Their number in a newborn is 3 times less than in an adult. Alveoli begin to develop from 4-6 weeks of age, their formation occurs up to 8 years. After 8 years, children’s lungs increase due to their linear size, and at the same time, the respiratory surface of the lungs increases.

The following periods can be distinguished in the development of the lungs:

1) from birth to 2 years, when intensive growth of the alveoli occurs;

2) from 2 to 5 years, when elastic tissue intensively develops, bronchi with peribronchial inclusions of lung tissue are formed;

3) from 5 to 7 years, the functional abilities of the lungs are finally formed;

4) from 7 to 12 years, when a further increase in lung mass occurs due to the maturation of lung tissue.

Anatomically, the right lung consists of three lobes (upper, middle and lower). By 2 years, the sizes of the individual lobes correspond to each other, like in an adult.

In addition to the lobar division, segmental division is distinguished in the lungs: in the right lung there are 10 segments, in the left - 9.

The main function of the lungs is breathing. It is believed that 10,000 liters of air pass through the lungs daily. Oxygen absorbed from the inhaled air ensures the functioning of many organs and systems; the lungs take part in all types of metabolism.

The respiratory function of the lungs is carried out with the help of a biologically active substance - surfactant, which also has a bactericidal effect, preventing fluid from entering the pulmonary alveoli.

The lungs remove waste gases from the body.

A feature of the lungs in children is the immaturity of the alveoli; they have a small volume. This is compensated by increased breathing: than younger child, the more shallow his breathing. The respiratory rate in a newborn is 60, in a teenager it is already 16-18 respiratory movements per minute. Lung development is completed by age 20.

A wide variety of diseases can impair life expectancy in children. important function breathing. Due to the characteristics of aeration, drainage function and evacuation of secretions from the lungs, the inflammatory process is often localized in the lower lobe. This occurs in a supine state in infants due to insufficient drainage function. Paravisceral pneumonia most often occurs in the second segment of the upper lobe, as well as in the basal-posterior segment of the lower lobe. The middle lobe of the right lung may often be affected.

The following studies are of greatest diagnostic importance: X-ray, bronchological, determination of blood gas composition, blood pH, study of external respiration function, study of bronchial secretions, computed tomography.

By the frequency of breathing and its relationship with the pulse, the presence or absence of respiratory failure(see table 14).

The respiratory organs ensure the exchange of gases between the human body and its environment. Without breath there is no life. A person absorbs oxygen from the air he inhales and releases carbon dioxide and water vapor. Stopping the supply of oxygen to the body causes death in a few minutes. Due to the oxygen entering the body, oxidative processes occur in the cells and tissues of the body, which represent a very significant part of metabolism. Carbon dioxide released as a result of oxidation is removed from the body through the lungs during exhalation.

In terms of their structure and functions, the respiratory organs in children and adolescents have a number of unique features that distinguish them from the respiratory organs in adults. The main features of the respiratory organs in children include the tenderness of their tissues, the slight vulnerability of the mucous membranes lining the respiratory tract, and the abundance of blood and lymphatic vessels in the mucous membranes and walls of the respiratory tract.

The upper respiratory tract, starting from the nasal cavities and nasopharynx, is much narrower in children than in adults, and is covered from the inside with a very delicate mucous membrane. The nasal cavities in young children are small and underdeveloped, and there is no glabella at all; it develops only by the age of 15. The paranasal cavities are also not yet sufficiently developed, and the frontal sinuses develop and form only by the age of 15.

These features largely determine the easier penetration of infection into the respiratory tract in children (statistically, children are twice as likely as adults to get the flu), as well as breathing problems due to various inflammatory processes in the nose. Thus, with a runny nose, young children experience difficulty breathing, which necessitates the participation of auxiliary muscles in the act of breathing, which is expressed in the swelling of the wings of the nose, and in older children - in breathing through the mouth. The last circumstance creates especially favorable conditions for introducing infection into the body of children and adolescents and penetration of dust particles into the respiratory system.

The pharynx in young children is still narrow. Tonsils in children begin to develop towards the end of the 1st year of life. Children often develop a peculiar disease known as adenoids, i.e., growths of a special type of lymphatic tissue (adenoid), which also makes up the paired tonsils of the pharynx. Most often, adenoid growths occur in children aged 4 to 10 years, although they also occur in adolescents.

Increased growth of the larynx in children is observed from the age of 5, when its strengthening is already noticeable. physiological functions. But especially intensive growth of the larynx occurs in adolescents, starting from 13-14 years old. At the same time, differentiation of the larynx according to gender is noticeable. By the end of puberty, the size of the larynx in boys and girls is not much different from the larynx of adults.

With the development and extension of true vocal cords, and with the strengthening of the cartilage of the larynx, the tones of the voice increase. The development and change in the shape of the neighboring cavities of the nasopharynx change its sonority and timbre. As children and adolescents age, the volume of their voice increases.

During puberty, adolescents experience a sharp change in their voice, which is especially pronounced in boys (“voice fracture”). Externally, the change in voice is manifested by a kind of hoarseness, easily turning into falsetto. The change in voice sometimes occurs suddenly and is explained by increased blood flow and swelling of the mucous membrane of the vocal cords. In subsequent years of adolescence, as well as in adulthood, different voice pitches are observed in men and women. For boys, the predominant sounds are chest sounds, and for girls - throat sounds.

One of the tasks of personal hygiene for children and adolescents is to take care of the protection and normal development of their voice. Basically, everything that relates to respiratory hygiene in children and adolescents can and should be used in its entirety to protect their voice (development of the respiratory system through breathing exercises and other exercises, voice training when learning to speak and sing, dust control and keeping mucous membranes clean, preventing colds, etc.). Especially useful for the development of the vocal apparatus in children and adolescents is rational teaching them to sing, as well as loud recitation with the correct stress and modulation. It should be noted that such gymnastics of the vocal apparatus also promotes the development of the chest and lungs.

But if concerns about the protection and development of the vocal apparatus are necessary in all age periods, then they are especially important during puberty, when the voice changes. During this period, boys and girls should not be allowed to sing a lot and thereby irritate and tire their vocal apparatus. Forgetting this position can lead to serious consequences: inflammation in the larynx, in particular, damage to the vocal cords, damage to the voice, etc. If redness appears in the throat and inflammation of the vocal cords, singing should be prohibited and sudden changes in temperature should be eliminated.

The mucous membrane of the trachea in children is very delicate, abundantly permeated with capillaries and has poorly developed elastic tissue.

The lumen of the bronchi in children is narrower than in adults; their cartilage has not yet become stronger. The muscle and elastic fibers of the bronchi are still poorly developed. The bronchi in children also have a more delicate mucous membrane and are abundantly supplied with blood vessels.

All this indicates that the trachea and bronchi in children are more vulnerable than in adults. The penetration of dust particles, as well as pathogenic (disease-causing) microorganisms into them poses a much greater danger for children compared to adults.

The lungs of children are still underdeveloped. Alveoli in newborns are 3-4 times smaller in size compared to adults. So, average diameter alveoli in a newborn is 0.07 mm, and in an adult 0.2 mm. Only gradually with age do the size of the alveoli increase. The capillaries of the lungs in children are much more developed than large blood vessels, and the lumen of the capillaries is wider than in adults. Lung growth in children and adolescents occurs throughout all periods of development of the body, but they grow most intensively in the first 3 months of life and during puberty, i.e., from the ages of 12 to 16 years inclusive. Intensive growth of the lungs during puberty requires special care about respiratory hygiene in adolescents, especially since unhygienic conditions at this age pose a threat in terms of lung diseases, in particular tuberculosis.

For the development of lungs in children and adolescents, exercises of the chest muscles are especially necessary. These muscles are less developed in children than in adults. Therefore, lack of exercise of the respiratory muscles adversely affects the development of the chest and lungs.

The chest grows most intensively in adolescents during puberty, when the respiratory muscles. In terms of circumference, the chest of boys in all periods is larger than that of girls, with the exception of the age from 13 to 15 years, when girls actively develop puberty and when all growth processes are activated in them.

The described features of the structure of the respiratory organs and the mechanism of their activity in children determine the nature of their respiratory movements. Breathing in children is more shallow and at the same time more frequent than in adults. The number of breaths in one minute is:
- in a newborn - 30-44 times;
- for a 5 year old child - 26 times;
- for teenagers 14-15 years old - 20 times;
- for an adult - 16-18 times.

During movement, exercise and physical labor breathing rate increases. Breathing in young children is not only superficial, but also uneven, unrhythmic and can vary from various reasons, which is explained by insufficient coordination of respiratory movements and slight excitability of their respiratory center in the medulla oblongata. During the first 5-6 years in children deep breaths alternate with superficial ones, and the intervals between inhalations and exhalations have different durations. Insufficient depth of breathing in children is of great importance from a hygienic point of view, since it completely does not provide sufficiently vigorous ventilation of the lungs in children. This is also confirmed by data characterizing the vital capacity of the lungs in children, which is an indicator of lung capacity and the strength of the respiratory muscles.

The vital capacity of the lungs in children 5 years old is on average 800-1,000 cm3. These data are relative, since the vital capacity of the lungs in individual individuals depends on the state of health, physique, degree of training, etc. Other researchers have obtained less data. Therefore, what is of interest here is not so much the absolute numbers characterizing the vital capacity of the lungs in children and adolescents of a particular age, but rather the process of changing them by age. The greatest increase in the vital capacity of the lungs is observed in adolescents during puberty, i.e., between the ages of 14 and 17 years. The increase in the vital capacity of the lungs generally occurs until the age of 20, although in subsequent years it can increase with appropriate training. It is important to note that due to more shallow breathing in children, a significant part of the inhaled air does not reach the pulmonary vesicles. This circumstance also confirms the fact of insufficient ventilation of the lungs in children and adolescents and puts forward the requirement for the longest possible stay in the fresh air in a state of active movement and ensuring good-quality indoor air.

However, the frequency and depth of breathing, taken separately from each other for judgment, cannot serve as a sufficient criterion for assessing the amount of ventilation of the lungs. Correct solution this question is given by the so-called minute volume breathing, i.e. the volume of breathing multiplied by the number of breaths per minute. In an adult, the minute volume of breathing reaches 10 liters (10,000 cm3), although it may be less. In children and adolescents, the minute volume of breathing is less, it is:
- in a newborn - 650-700 cm3;
- for a 1 year old child - 2,600 cm3;
- for a 5 year old child - 5,800 cm3;
- for adolescents 12 years old - 8000 cm3;
- for an adult - 10,000 cm3.

Energy metabolism in children is more intense than in adults. In this regard, children need relatively more air than adults. This is also confirmed by the fact that the minute volume of respiration in relation to 1 kg of body weight in children and adolescents is greater than in adults, and it decreases as they grow. Thus, the minute volume of the lungs in relation to 1 kg of body weight is:
- in an infant - 220 cm3
- in a 6-year-old child - 168 cm3;
- in a 14-year-old teenager - 128 cm3;
- in an adult 96 cm3.

The need for more intensive ventilation in children and adolescents is associated with the construction and development of tissues and an increase in body weight.

Breathing movements have positive influence for the whole body. Thus, movements of the diaphragm and intercostal muscles have a massaging effect on the organs of the thoracic and abdominal cavities. The deeper the breath, the stronger this massaging effect will be. But besides this, the rhythm of breathing affects the body through nervous system. Thus, its effect on heart rate and blood pressure is known.

The change in inhalation and exhalation also affects mental work. When the thought is intense, the breath is usually held somewhat. Attention intensifies when you exhale and hold your breath, and it weakens and dissipates when you inhale. From here it is obvious that when rapid breathing concentrated thought and generally productive mental work are difficult. Therefore, before starting serious mental work, it is necessary to calm your breathing. It is noticed that the correct rhythmic breathing promotes concentrated mental work.

Moving on to respiratory hygiene in children and adolescents, we should first of all point out the need for constant care for the normal development of the chest. The main ones in this direction are: correct position body, especially while sitting at a desk and at home when preparing lessons, breathing exercises and others physical exercise, developing the muscles that control the movements of the chest. Particularly useful in this regard are sports such as swimming, rowing, skating and skiing.

Teaching children to breathe properly is also one of the important hygienic provisions. Correct breathing- This is, first of all, uniform, rhythmic breathing. Correct breathing is only possible through the nose. Breathing at open mouth happens in children either with a runny nose or other inflammatory phenomena in the upper respiratory tract, or with adenoid growths in the nasopharynx. When breathing through the nose, a kind of barrier is created for penetration into the respiratory tract. pathogenic microorganisms and dust particles. In addition, when breathing through the nose, cold atmospheric air is warmed in the nasal cavities and enters the larynx and underlying respiratory tract uncooled, which happens when breathing through the mouth. Thus, breathing through the nose protects children and adolescents from diseases of bronchitis and catarrh of the deep respiratory tract. It is especially important to breathe through your nose when walking quickly. winter frosts, since this deepens breathing, and breathing through the mouth entails a sharp cooling of the respiratory tract.

Dry air, which often irritates the respiratory tract, decreases when breathing through the nose, since air is humidified in the nasal cavities through the moist mucous membrane. Breathing through the nose is a sign healthy body, ensures rhythmic breathing and a relatively large depth, which in turn has a positive effect on lung ventilation.

One of the important requirements for respiratory hygiene in children and adolescents is the need to teach children to walk and stand in an upright position, as this promotes expansion of the chest, facilitates the functioning of the lungs and ensures better health. deep breathing. On the contrary, when the body is bent, reverse conditions are created that disrupt the normal activity and development of the lungs, and they absorb less air, and with it oxygen.

In the system of organizing the life and educational work of children and adolescents, it is necessary to pay special attention to ensuring that they spend as much time as possible in the fresh air and that their stay in it is associated with movement. Therefore, it is so important in the summer, and, if possible, during the winter holidays, to take children and teenagers to dachas, pioneer camps, forest schools, where they can be in the fresh air.

IN winter time years for children preschool age it is necessary to be in the fresh air for at least 5 hours a day, not in a row, but at intervals, with the exception of severe frosts below 15°, especially when there is wind; for children of primary school age - at least 4 hours and for senior school age - at least 3 hours a day. For the same purposes, it is necessary to provide students in schools with the opportunity to spend breaks between lessons, especially a long break, in the school site. For the same reasons, it is imperative to keep the air in the apartment and classroom constantly fresh and systematically, several times a day, to ventilate residential and school premises.

All the above hygiene measures, in addition to their importance for the normal development and functioning of the respiratory organs, are one of essential means hardening respiratory system and no less important from the point of view of preventing diseases in this area. Respiratory diseases in children and adolescents are most often observed in winter and spring. That's why special meaning in this direction they acquire: rational clothing for children and adolescents in accordance with the season, hardening skin care and gradual accustoming of the body to temperature changes. It should be borne in mind that pampering and fearful avoidance fresh air are one of the main factors contributing to the occurrence of catarrhal lesions of the respiratory system (

The respiratory organs are in close connection with the circulatory system. They enrich the blood with oxygen, necessary for oxidative processes occurring in all tissues.

Tissue respiration, that is, the use of oxygen directly from the blood, occurs in the prenatal period, along with the development of the fetus, and external breathing, i.e., the exchange of gases in the lungs, begins in the newborn after cutting the umbilical cord.

What is the mechanism of breathing?

With each inhalation, the chest expands. The air pressure in it decreases and, according to the laws of physics, outside air enters the lungs, filling the rarefied space formed here. When you exhale, the chest contracts and air from the lungs rushes out. The chest is brought into motion thanks to the work of the intercostal muscles and the diaphragm (the abdominal barrier).

The act of breathing is controlled by the breathing center. It is located in the medulla oblongata. Carbon dioxide accumulating in the blood serves as an irritant to the respiratory center. Inhalation is replaced by exhalation reflexively (unconsciously). But the higher department, the cerebral cortex, also takes part in the regulation of breathing; with an effort of will you can a short time hold your breath or make it more frequent, deeper.

The so-called airways, i.e., nasal cavities, larynx, bronchi, are relatively narrow in a child. The mucous membrane is tender. It has a dense network of tiny vessels (capillaries), is easily inflamed and swells; this leads to the switching off of breathing through the nose.

Meanwhile, nasal breathing very important. It warms, moisturizes and cleanses (which helps preserve tooth enamel) the air passing into the lungs, irritates the nerve endings that affect the stretching of the bronchi and pulmonary vesicles.

Increased metabolism and, in connection with this, an increased need for oxygen and active motor activity lead to an increase in the vital capacity of the lungs (the amount of air that can be exhaled after a maximum inhalation).

In a three year old child vital capacity lungs close to 500 cm cubic; by the age of 7 it doubles, by 10 it triples, and by 13 it quadruples.

Due to the fact that the volume of air in the airways of children is less than that of adults, and the need for oxidative processes is high, the child has to breathe more often.

The number of respiratory movements per minute in a newborn is 45-40, in a one-year-old - 30, in a six-year-old - 20, in a ten-year-old - 18. In physically trained people, the respiratory rate at rest is lower. This is due to the fact that they breathe more deeply. and the oxygen utilization rate is higher.

Hygiene and training of the respiratory tract

It is necessary to pay serious attention to the respiratory hygiene of children, in particular to hardening and accustoming them to nasal breathing.