home Adviсe Features of the structure and development of the respiratory system in children. Anatomical and physiological features of the respiratory system in children

Features of the structure and development of the respiratory system in children. Anatomical and physiological features of the respiratory system in children

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.

For the birth of a child Airways(larynx, trachea, bronchi and acini) are 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 of 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 insufficient development of cavernous tissue in children early age The inhaled air is poorly warmed, and 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

Name of sine	Intrauterine development period, months	Size at birth, mm	Period of fastest development	Detection time during X-ray examination
Lattice			By 7-12 years
Maxillary			From 2 to 7 years
Frontal			Slow until age 7, fully developed by age 15-20
Wedge-shaped			Slow until age 7, fully developed by age 15

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 (smaller 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. Hyperplasia is observed in the second year of life lymphoid tissue, and the tonsils emerge from behind 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 is less common with respiratory allergies. 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. The middle lobe of the 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 V last 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 during 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 the frequent form of 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.

About 70% of childhood diseases are caused by disorders normal operation respiratory organs. They are involved in passing air through the lungs, while preventing the entry of pathogenic microorganisms and further development of the inflammatory process. At the slightest disruption in the full functioning of the respiratory organs, the entire body suffers.

Photo: Respiratory organs

Features of the respiratory system in childhood

Respiratory diseases in children occur with some peculiarities. This is due to a number of factors:

narrowness of the nasal passages and glottis;
insufficient depth and increased frequency of breathing;
low airiness and increased lung density;
poor development of respiratory muscles;
unstable breathing rhythm;
tenderness of the nasal mucosa (rich in blood vessels and easily swells).

Photo: Respiratory muscles

The respiratory system becomes mature no earlier than 14 years of age.. Until this moment, the pathologies attributed to it need to be given increased attention. Disease detection respiratory system should occur in a timely manner, which increases the chances of a speedy cure bypassing complications.

Causes of diseases

The child's respiratory organs are often exposed. More often pathological processes develop under the influence of activation of staphylococci and streptococci. Allergies often lead to disturbances in the functioning of the respiratory system.

Among the disposing factors are not only anatomical features respiratory organs in childhood, as well as an unfavorable external environment, hypovitaminosis. Modern children with noticeable regularity do not follow a daily routine and do not eat properly, which affects the body’s defenses and subsequently leads to diseases. The situation may be aggravated by the lack of hardening procedures.

Photo: Activation of staphylococci is the cause of the disease

Symptoms

Despite the existence of signs characteristic of each individual disease of the child’s respiratory system, doctors identify common ones:

(obligatory symptom, peculiar defensive reaction organism);
dyspnea(signals a lack of oxygen);
sputum(special mucus produced in response to the presence of irritants);
nasal discharge(can be different color and consistency);
labored breathing;
temperature increase(this also includes general intoxication of the body, which is a combination of the body’s biological reactions to infection).

Photo: Sputum

Diseases of the respiratory system are divided into two groups. The former affect the upper respiratory tract (URT), the latter - lower sections(NDP). In general, it is not difficult to determine the onset of one of the respiratory diseases in a child, especially if a doctor takes over the work. Using a special device, the doctor will listen to the child and perform an examination. If clinical picture turns out to be blurred, a detailed examination will be needed.

Photo: Examination of a child by a doctor

Upper respiratory tract diseases

Viruses and bacteria can lead to pathologies. It is known that the presented group of diseases is one of common reasons appeal of the child's parents to the pediatrician.

According to static data, a child of preschool and primary school age can experience from 6 to 10 episodes of disruption of the upper respiratory tract per year.

Inflammation of the nasal mucosa that occurs due to a viral infection. The impetus for the development of rhinitis can be banal hypothermia, which as a result reduces the body's defenses.

Photo: Rhinitis

Acute rhinitis may be a symptom of acute infectious disease or manifest as an independent pathology.

Photo: Lower respiratory tract

Tracheitis occurs extremely rarely as an independent disease.

Photo: Breathing exercises

Is it possible to prevent trouble?

Any respiratory disease can be prevented. For this purpose, you need to temper the child’s body, regularly take him for walks. fresh air, always dress according to the weather. It is very important to avoid hypothermia and wet feet. In the off-season, the child’s health should be supported with vitamin complexes.

At the first signs of discomfort, you should contact a specialist.

Photo: At a doctor's appointment

Respiratory organs in a child differ significantly from the respiratory system of an adult. By the time of birth, the child’s respiratory system has not yet reached full development, therefore, in the absence of proper care, children experience an increased incidence of respiratory diseases. The largest number of these diseases occur between the ages of 6 months and 2 years.

Studying the anatomical and physiological characteristics of the respiratory organs and conducting a wide range of preventive measures Taking these features into account, they can contribute to a significant reduction in respiratory diseases, which are still one of the main causes of child mortality.

Nose the child is relatively small, the nasal passages are narrow. The mucous membrane lining them is tender, easily vulnerable, rich in blood and lymphatic vessels; this creates conditions for the development of an inflammatory reaction and swelling of the mucous membrane during infection of the upper respiratory tract.

Normally, a child breathes through his nose; he cannot breathe through his mouth.

With age as development progresses upper jaw and the growth of facial bones, the length and width of the burrows increase.

Eustachian tube, which connects the nasopharynx to tympanic cavity ear, relatively short and wide; it has a more horizontal direction than that of an adult. All this contributes to the introduction of infection from the nasopharynx into the middle ear cavity, which explains the frequency of its involvement in upper respiratory tract disease in a child.

The frontal sinus and maxillary cavities develop only by 2 years, but they reach their final development much later.

Larynx in young children it has a funnel shape. Its lumen is narrow, the cartilage is pliable, the mucous membrane is very delicate, rich in blood vessels. The glottis is narrow and short. These features explain the frequency and ease of narrowing of the glottis (stenosis), even with relatively moderate inflammation of the laryngeal mucosa, which leads to difficulty breathing.

Trachea and bronchi also have a narrower clearance; their mucous membrane is rich in blood vessels; when inflamed, it easily swells, which causes a narrowing of the lumen of the trachea and bronchi.

Lungs, infant differ from the lungs of an adult in the weak development of elastic tissue, greater blood supply and less airiness. The weak development of the elastic tissue of the lung and insufficient excursion of the chest explains the frequency of atelectasis (collapse lung tissue) and infants, especially in the lower posterior sections of the lungs, since these sections are poorly ventilated.

Lung growth and development occurs over a fairly long period of time. Lung growth is especially vigorous in the first 3 months of life. As the lungs develop, their structure changes: connective tissue layers are replaced by elastic tissue, the number of alveoli increases, which significantly increases the vital capacity of the lungs.

Thoracic cavity the child's is relatively small. The respiratory excursion of the lungs is limited not only due to the low mobility of the chest, but also due to its small size pleural cavity, which in a young child is very narrow, almost slit-like. Thus, the lungs almost completely fill the chest.

The mobility of the chest is also limited due to weakness of the respiratory muscles. The lungs expand mainly towards the pliable diaphragm, therefore, before walking, the type of breathing in children is diaphragmatic. With age breathing excursion The chest enlarges and a thoracic or abdominal type of breathing appears.

Age anatomical and morphological features chest cause some functional features breathing of children at different ages.

The oxygen requirement of a child during a period of intensive growth is very high due to increased metabolism. Since breathing in infants and young children is superficial, the high oxygen demand is covered by the respiratory rate.

Within a few hours after the newborn’s first breath, breathing becomes correct and fairly uniform; sometimes it is established only after a few days.

Number of respirations in a newborn up to 40-60 per minute, in a child of 6 months - 35-40, in 12 months - 30-35, in 5-6 years - 25, at the age of 15 years - 20, in an adult - 16.

The number of respirations must be counted calm state child, watching the breathing movements of the chest or placing a hand on the stomach.

Vital capacity of the lungs the child's is relatively large. In school-age children, it is determined by spirometry. The child is asked to take a deep breath and special device- spirometer - measure the maximum amount of air exhaled after this ( table 6.) (according to N.A. Shalkova).

Table 6. Vital capacity of the lungs in children (in cm3)

Age in years	Boys	Limits fluctuations

With age, the vital capacity of the lungs increases. It also increases as a result of training, with physical work and playing sports.

Breathing is regulated by the respiratory center, which receives reflex irritations from the pulmonary branches vagus nerve. The excitability of the respiratory center is regulated by the cerebral cortex and the degree of blood saturation with carbon dioxide. With age, cortical regulation of breathing improves.

As the lungs and chest develop and the respiratory muscles strengthen, breathing becomes deeper and less frequent. By the age of 7-12, the breathing pattern and shape of the chest are almost no different from those of an adult.

The correct development of the child's chest, lungs and respiratory muscles depends on the conditions in which he grows. If a child lives in a stuffy room where people smoke, cook food, wash and dry clothes, or is in a stuffy, unventilated room, then conditions are created that disrupt the normal development of his chest and lungs.

To improve the child's health and good development respiratory organs, to prevent respiratory diseases, it is necessary for the child to spend a long time in the fresh air in winter and summer. Outdoor games, sports and physical exercise are especially useful.

Exclusively important role in strengthening the health of children, it is necessary to take them out of the city, where it is possible to organize the children’s stay in the air for the whole day.

The rooms in which children are located must be thoroughly ventilated. In winter, you should open the windows or transoms several times a day according to the established procedure. In a room with central heating, if there are transoms, ventilation can be carried out very often without cooling it. During the warm season, windows should be open around the clock.

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, a trunk is formed pulmonary artery, 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. Within 3 months, the bronchial tree grows, 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 this period, with the onset of breathing, significant changes occur in the 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, the condition and readiness of the surfactant film lining the lung surface are of great importance. 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.

period of intensive growth of the pulmonary lobes (from 3 months to 3 years).
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 the upper, which includes the nose, paranasal sinuses, pharynx, eustachian tubes, and lower, which include the larynx, trachea, and 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 carbon dioxide occurs in dissolved form, oxygen saturation of the blood affects the carbon dioxide content.

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.

Respiratory diseases in children may cause problems respiratory function and respiratory failure.

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 finally 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 a disturbance in appetite, as well as a disturbance in the understanding of the external environment. Breathing through the nose is physiological, breathing through the mouth is a sign of nasal disease.

Accessory nasal cavities. 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 pharynxbaby

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 its 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 enters the middle ear from the nasopharynx, middle ear inflammation occurs.

Features of the larynxbaby

The larynx in children is funnel-shaped and is an extension 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 breathing problems.

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 tracheababy

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 in a newborn is located at the level III chest 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, disruption of the cleansing drainage function 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 it occurs intensive growth alveoli;

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 right lung There are 10 segments, 9 on the left.

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 using biological active substance— a 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.

The most various diseases may interfere with the life expectancy of 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 when children are lying down infancy 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.

Greatest diagnostic value have the following studies: x-ray, bronchology, 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 system is a collection of organs consisting of the respiratory tract (nose, pharynx, trachea, bronchi), lungs (bronchial tree, acini), as well as muscle groups that promote contraction and relaxation of the chest. Breathing provides the body's cells with oxygen, which in turn convert it into carbon dioxide. This process occurs in the pulmonary circulation.

The formation and development of the child’s respiratory system begins during the 3rd week of a woman’s pregnancy. Formed from three primordia:

Splanchnotome.
Mesenchyme.
Epithelium of the foregut.

The pleural mesothelium develops from the visceral and parietal layers of the splanchnotome. It is represented by a single-layer squamous epithelium (polygonal cells), lining the entire surface of the pulmonary system, separating it from other organs. External surface The leaf is covered with microcilia that produce serous fluid. It is necessary for the two layers of pleura to slide between each other during inhalation and exhalation.

From the mesenchyme, namely the germ layer of the mesoderm, cartilage, muscle and connective tissue structures are formed, blood vessels. The bronchial tree, lungs, and alveoli develop from the epithelium of the foregut.

During the prenatal period, the respiratory tract and lungs are filled with fluid, which is removed during childbirth with the first breath, and is also absorbed by the lymph system and partially into the blood vessels. Breathing is carried out by maternal blood enriched with oxygen through the umbilical cord.

By the eighth month of gestation, pneumocytes produce a surfactant - surfactant. He's lining inner surface alveoli, prevents their collapse and adhesion, is located at the air-liquid boundary. Protects against harmful agents with the help of immunoglobulins and macrophages. Insufficient secretion or absence of surfactant threatens the development of respiratory distress syndrome.

A feature of the respiratory system in children is its imperfection. Formation and differentiation of tissues, cellular structures performed in the first years of life and up to seven years.

Structure

Over time, the child’s organs adapt to the environment in which he will live, and the necessary immune and glandular cells are formed. In a newborn, the respiratory tract, unlike an adult body, has:

Narrower clearance.
Short stroke lengths.
Many vascular vessels in a limited area of the mucosa.
The delicate, easily traumatized architectonics of the lining membranes.
Loose structure of lymphoid tissue.

Upper paths

Baby's nose small size, its passages are narrow and short, so the slightest swelling can lead to obstruction, which will complicate the sucking process.

Structure upper paths The child has:

Two nasal sinuses are developed - the upper and middle, the lower one will be formed by the age of four. The cartilage frame is soft and pliable. The mucous membrane has an abundance of blood vessels and lymphatic vessels, and therefore minor manipulation can lead to injury. Rarely noted nose bleed– this is due to undeveloped cavernous tissue (it will be formed by the age of 9). All other cases of bleeding from the nose are considered pathological.
The maxillary sinuses, frontal and ethmoid sinuses are not closed, protrude the mucous membrane, are formed by 2 years of age, cases of inflammatory lesions are rare. Thus, the shell is more adapted to cleansing and humidifying the inhaled air. Full development of all sinuses occurs by age 15.
The nasolacrimal duct is short, exits in the corner of the eye, close to the nose, which ensures rapid upward spread of inflammation from the nose to the lacrimal sac and the development of polyetiological conjunctivitis.
The pharynx is short and narrow, which allows it to quickly become infected through the nose. At the level between the oral cavity and the pharynx there is a nasopharyngeal ring-shaped Pirogov-Waldeyer formation, consisting of seven structures. The concentration of lymphoid tissue protects the entrance to the respiratory and digestive organs from infectious agents, dust, and allergens. Features of the structure of the ring: poorly formed tonsils, adenoids, they are loose, susceptible to colonization of inflammatory agents in their crypts. Chronic foci of infection, frequent respiratory diseases, sore throats, and difficulty in nasal breathing occur. Such children appear neurological disorders, they usually go with open mouth and are less amenable to schooling.
The epiglottis is scapula-shaped, relatively wide and short. During breathing, it rests on the root of the tongue - it opens the entrance to lower paths, during the period of eating – prevents the entry foreign body into the respiratory passages.

Lower Paths

The larynx of a newborn is located higher than that of an adult and is very mobile due to the muscular frame. It looks like a funnel with a diameter of 0.4 cm, the narrowing is directed towards the vocal cords. The chords are short, which explains the high timbre of the voice. With slight swelling, during acute respiratory diseases, symptoms of croup and stenosis occur, which is characterized by heavy, wheezing breathing with the inability to take a full breath. As a result, hypoxia develops. The laryngeal cartilages are rounded, their sharpening in boys occurs by the age of 10–12 years.

At the time of birth, the trachea is already formed, located at the level of the 4th cervical vertebra, mobile, funnel-shaped, then acquires a cylindrical appearance. The lumen is significantly narrowed, unlike in an adult; there are few glandular areas in it. When coughing, it can shrink by a third. Considering the anatomical features, during inflammatory processes, narrowing and the occurrence of barking cough, symptoms of hypoxia (cyanosis, shortness of breath). The tracheal framework consists of cartilaginous half-rings, muscle structures, and a connective tissue membrane. The bifurcation at birth is higher than in older children.

The bronchial tree is a continuation of the tracheal bifurcation and is divided into the right and left bronchus. The right one is wider and shorter, the left one is narrower and longer. The ciliated epithelium is well developed, producing physiological mucus that cleanses the bronchial lumen. Mucus moves outward with cilia at a speed of up to 0.9 cm per minute.

A feature of the respiratory system in children is weak cough impulse, due to poorly developed torso muscles, incomplete myelin coating of the nerve fibers of the tenth pair of cranial nerves. As a result, infected sputum does not pass away, accumulates in the lumen of bronchi of different sizes and becomes clogged with thick secretions. The structure of the bronchus contains cartilaginous rings, with the exception of the terminal sections, which consist only of smooth muscle. When they are irritated, a sharp narrowing of the passage may occur - an asthmatic picture appears.

The lungs are an air tissue, their differentiation continues until the age of 9, they consist of:

Lobes (right of three, left of two).
Segments (right – 10, left – 9).
Dolek.

The bronchioles end in a sac in the baby. As the child grows, lung tissue grows, the sacs turn into alveolar clusters, and vital capacity indicators increase. Active development from the 5th week of life. At birth, the weight of the paired organ is 60–70 grams, well supplied with blood and vascularized with lymph. Thus, it is full-blooded, and not airy as in older people. An important point is that the lungs are not innervated, inflammatory reactions are painless, and in this case, you can miss a serious illness.

Due to the anatomical and physiological structure, pathological processes develop in the basal sections, and cases of atelectasis and emphysema are not uncommon.

Functional Features

The first breath is carried out due to a decrease in oxygen in the blood of the fetus and an increase in the level of carbon dioxide, after clamping the umbilical cord, as well as a change in living conditions - from warm and humid to cold and dry. Signals along nerve endings enter the central nervous system and then to the respiratory center.

Features of respiratory function in children:

Conducting air.
Cleaning, warming, moisturizing.
Saturation with oxygen and purification from carbon dioxide.
Protective immune function, synthesis of immunoglobulins.
Metabolism – synthesis of enzymes.
Filtration – dust, blood clots.
Lipid and water metabolism.
Shallow breaths.
Tachypnea.

In the first year of life, respiratory arrhythmia occurs, which is considered normal, but its persistence and the occurrence of apnea after one year of age is fraught with respiratory arrest and death.

The frequency of breathing movements directly depends on the age of the baby - the younger, the more often the breath is taken.

NPV norm:

Taking into account the characteristics of the respiratory system in children, the attentiveness and awareness of parents, timely examination, therapy reduces the risk of transition to chronic stage illness and serious complications.