Age-related breathing characteristics. The large surface area of ​​the alveoli promotes better gas exchange. · Breathing is one of the main processes of functioning and vital activity of the human body; without breathing, life can last only a few

Human breathing in age dynamics.

The development of the lungs in the human embryo begins at the 3rd week of embryonic life. Between the 5th week and 4th month of the embryo’s life, bronchi and bronchioles form; by the time of birth, the number of pulmonary segments is already the same as in an adult.

The child prepares for independent breathing in advance - as soon as labor begins. The first breath occurs under the influence of a combination of many factors: irritation of the skin as the child passes through birth canal and immediately after birth, changing the position of his body, ligating the umbilical cord. A powerful stimulant the respiratory center is cold irritation - a temperature difference during birth of 12 - 16 degrees.

The fetal lungs are filled with fluid produced by respiratory epithelial cells. As the baby moves through the birth canal, its chest is compressed and fluid is forced out of the airway. Negative pressure is created in the chest, and atmospheric air is sucked into it. The first portions of air fill only those Airways, which were freed from fluid during childbirth.

During childbirth, during contractions, placental circulation is disrupted, the supply of oxygen to the child’s body decreases, as a result of which carbon dioxide accumulates in his blood and tissues.

Hypercapnia and hypoxia, which occur during childbirth and in the first seconds and minutes of a newborn’s life, lead to a sharp excitation of the respiratory center in the medulla oblongata. A convulsive contraction of the diaphragm and skeletal muscles involved in breathing occurs, and the lungs expand. At this moment, the first breath occurs, accompanied by the cry of the newborn baby.

The respiratory rate of full-term newborns in the 1st week of life ranges from 30 to 50 per minute.

The main structural unit of the lung in a child (as well as in an adult) is the acinus. In newborns, the acinus is not sufficiently differentiated. Differentiation occurs long after birth. For example, in a newborn the number of alveoli is 24 million, and their diameter is 0.05 mm, which is 12 times and, accordingly, 4 times less than in adults. If the weight of a newborn’s lungs is 50 g, then by 1 year it increases 3 times, by 12 - 10 times, and in an adult - 20 times.

The child’s lungs are poor in elastic fibers, especially in the circumference of the alveoli and in the walls of the pulmonary capillaries; between the lobules of the lungs and the alveoli, loose connective tissue, rich in blood vessels. Up to 3 years, increased differentiation of individual elements of the lungs occurs; from 3 to 7 years, its pace slows down. By the age of 7-8 years, the processes of differentiation of the bronchi end. Particularly enhanced growth and improvement of the respiratory organs is observed in the puberty period (12-16 years). During this period, the nasal passages, larynx, trachea and the general surface of the lungs reach their maximum development. The lumen of the trachea and bronchi increases, their muscle and elastic fibers develop.

IN puberty the volume of the lungs increases due to an increase in the volume of the alveoli (their number reaches the adult level by 8 years (Fig. 16)). At the same time, the volume of the lungs and the surface of the alveoli are still significantly smaller than in adults.

Due to the difficulty of determining vital capacity of the lungs (vital capacity of the lungs) in newborns, they usually determine the vital capacity of the cry, considering that with a very strong cry, the volume of exhaled air is almost equal to vital capacity. Thus, they were able to determine vital capacity in the first minutes after birth: it was 56-110 ml.

In children, vital capacity is usually measured from 4-6 years of age. To a large extent, it depends on physical development, age, gender, etc. Figure 17 shows the average values ​​of vital capacity depending on age and gender. As you can see, vital capacity increases with age, with the greatest increase observed at 12-17 years of age (puberty), reaching the value for an adult by 17 years of age.

The respiratory rate per minute in children of the first year of life is 29-60. In children 1-2 years old this value is 35-40, in 2-4 year olds 25-35, in 4-6 year olds - 23-26 cycles per minute. In children school age a further decrease in breathing occurs (up to 18-20 times). The child's high breathing rate ensures high pulmonary ventilation.

Volume breathing air(DO) in a child at 1 month is 30 ml, at 1 year - 70 ml, at 6 years - 156 ml, at 10 - 230 ml, at 14 years - 300 ml, and only by the age of 16-17 it reaches the size of an adult .

Minute breathing volume is the amount of air that a person inhales in 1 minute. In a newborn, MOD is 650-700 ml, by the end of the first life - 2700 ml, by 6 years - 3500 ml, in an adult - 5000-6000 ml.

In the process of growth and development of the body, with an increase in the inspiratory reserve, the maximum ventilation of the lungs or maximum voluntary ventilation (MVV) also increases. Let us remember that this means the maximum capacity of the breathing apparatus. To determine it, a person is asked to breathe as often and deeply as possible for 15 seconds.

The value of MPV increases over time, reaching the level of an adult by the age of 16-17 years.

From about 11 years of age, the increase in MPV in girls begins to lag behind that in boys.

MPV in preschoolers is 10 times greater than MPV; in puberty 13 times; on average in an adult - 20-25 times. This shows that in the process of growth and development of the body, external respiration reserves increase.

In the fetus, the gas exchange organ is the placenta, and the supply of oxygen depends on the oxygen tension in the mother’s blood, the oxygen capacity of the fetus’s blood, the characteristics of its hemoglobin, etc. At this period of development, the body has special adaptive mechanisms that ensure the delivery of oxygen to tissues. The oxygen capacity of the fetal blood is increased towards the end of intrauterine life. Fetal hemoglobin has an increased affinity for oxygen; the dissociation curve of the oxyform of hemoglobin is shifted to the left, which facilitates the flow of oxygen from the mother’s body into the fetal blood. An increase in the oxygen capacity of the fetal blood is an important mechanism of biological adaptation to the conditions of intrauterine life. By the 35-40th day of postnatal life, the oxyhemoglobin dissociation curve approaches that of an adult.

High intensity of oxidative metabolism shown above, features of external respiration function, blood circulation, respiratory function blood determine the uniqueness of the body’s oxygen regimes on early stages its development. Due to the lower power of the breathing apparatus, the rate of oxygen entering the child’s lungs is low. As the body's oxygen demand increases with age, the total volume and power of the respiratory organs, pulmonary ventilation, and with it the rate of oxygen supply to the lungs increases.

The changing relationship between the rate of oxygen delivery and its consumption leads to the fact that the body's oxygen regimes become more and more efficient with age. An increase in the efficiency of oxygen regimes is manifested in the fact that the “idle” flow of venous blood, in terms of providing tissues with oxygen, decreases; oxygen transport rate venous blood exceeds the rate of its tissue consumption by 2.2-2.4 times in the first (4-7 years) and second childhood (8-12 years), 2.7-2.8 times in adolescence (13-16 years ) and only 1.7 times in adults.

The general trend towards increasing the efficiency of the body's oxygen regimes during the growth and development of a child and adolescent is due to the fact that the regulation of breathing and blood circulation becomes more and more perfect with age, and the functions of these systems are more economical. For example, in a child, for every liter of oxygen consumed, there are 29-30, and in adolescents, 32-34 liters of air passing through the lungs, while in an adult it is only 24-25 liters. To deliver 1 liter of oxygen to tissues, a child and a teenager need 22-21 liters of blood; an adult only needs 15-16 liters.

One of best models physical activity is used to identify the functional capabilities of external respiration and the entire gas exchange and gas transport system.

In children and adolescents, during muscular work, oxygen consumption cannot increase to the same levels as in adults. Children have lower maximum values ​​of pulmonary ventilation and blood flow. For example, during physical activity (BMD test), pulmonary ventilation in children and adolescents increases only 10-12 times (8-9 years - up to 50-60 l/min; 14-15 years - up to 60-70 l/min ), while even in untrained adults it reaches 100 l/min.

Due to small size heart, less power of the heart muscle, systolic blood volume in children and adolescents during intense muscular activity cannot increase as much as in adults.

The increase in pulmonary ventilation in children during exercise is carried out mainly due to increased breathing, and not due to an increase in the tidal volume of inhalation and exhalation. A small increase in the diffusion surface of the lungs during exercise is the reason for less utilization of oxygen from the alveolar air. For example, 1 liter of oxygen in children at rest is extracted from 5 liters, and in adults from 3.5 liters of air entering the alveoli. During physical activity, the oxygen utilization rate increases approximately 2 times, and in adults, 3 times.

The use of oxygen from arterial blood in children is approximately 50%, while in adults it is 70% (in high-class athletes it reaches 85-90%). The relatively small oxygen capacity of the blood and the lower utilization of oxygen from it lead to the fact that in children and adolescents during physical activity the efficiency of blood circulation is not as high as in adults. Less performance, lower efficiency and economy of oxygen regimes indicate worse regulation of oxygen regimes in the child’s body during muscular work.

Fetal breathing. Respiratory movements in the fetus occur long before birth. The stimulus for their occurrence is a decrease in the oxygen content in the blood of the fetus.

The breathing movements of the fetus consist of a slight expansion of the chest, which is followed by a longer decline, and then an even longer pause. When inhaling, the lungs do not expand, but only a slight negative pressure appears in the pleural fissure, which is absent at the time of collapse chest. Meaning breathing movements The fetus is that they help increase the speed of blood movement through the vessels and its flow to the heart. And this leads to improved blood supply to the fetus and oxygen supply to tissues. In addition, fetal breathing movements are considered a form of lung function training.

Breathing of a newborn. The occurrence of the first breath of a newborn is due to a number of reasons. After ligation of the umbilical cord in a newborn, the placental exchange of gases between the blood of the fetus and mother stops. This leads to an increase in blood levels carbon dioxide irritating cells respiratory center And causing rhythmic breathing.

The reason for the first breath of a newborn is a change in the conditions of his existence. The action of various environmental factors on all body surface receptors becomes the irritant that reflexively contributes to the occurrence of inhalation. A particularly powerful factor is irritation of skin receptors.

A newborn's first breath is especially difficult. When it is carried out, the elasticity of the lung tissue is overcome, which is increased due to the surface tension forces of the walls of the collapsed alveoli and bronchi. The formation in the alveoli contributes to the reduction of surface tension forces. surfactant. It is believed that to stretch the lungs, a certain change in the shape of the chest with age is necessary, matching the force of contraction respiratory muscles and compliance of lung tissue. If the muscles are weak, stretching of the lungs will not occur and breathing movements will not occur.

After the first 1 to 3 respiratory movements occur, the lungs are fully expanded and evenly filled with air. During the first inhalation, the air pressure in the lungs becomes equal to atmospheric pressure and the lungs stretch to such an extent that the layers of the visceral and parietal pleura come into contact with each other.

The chest grows faster than the lungs, so pleural cavity Negative pressure arises, and conditions are created for constant stretching of the lungs. Creating negative pressure in the pleural cavity and maintaining it at a constant level also depends on the properties of the pleural tissue. It has high absorption capacity. Therefore, gas introduced into the pleural cavity and reducing the negative pressure in it is quickly absorbed, and the negative pressure in it is restored again.

The mechanism of breathing in a newborn. The child's breathing patterns are related to the structure and development of his chest. In a newborn, the chest has a pyramidal shape; by the age of 3 it becomes cone-shaped, and by the age of 12 it becomes almost the same as that of an adult. Upper ribs, manubrium, clavicle and entire shoulder girdle in a newborn they are located high. All ribs lie almost horizontally, the respiratory muscles are weak. Due to this structure, the chest takes little part in the act of breathing. This is accomplished mainly by lowering the diaphragm.

Newborns have an elastic diaphragm, its tendon part occupies a small area, and the muscle part occupies a large area. As it develops, the muscular part of the diaphragm increases even more. It begins to atrophy from the age of 60, and in its place the tendon part increases.

Since infants mainly breathe diaphragmatically, during inhalation the resistance of the internal organs located in the abdominal cavity. In addition, when breathing, you have to overcome the elasticity of the lung tissue, which is still high in newborns and decreases with age. One also has to overcome bronchial resistance, which is much greater in children than in adults. Therefore, the work spent on breathing is much greater in children compared to adults.

Changes in breathing type with age. Diaphragmatic breathing persists until the second half of the first year of life. As the child grows, the chest moves down and the ribs take on an oblique position. In this case, infants experience mixed breathing (thoracic-abdominal), and stronger mobility of the chest is observed in its lower parts. Due to the development of the shoulder girdle (3–7 years), chest breathing begins to predominate. From 8 to 10 years of age, gender differences in the type of breathing arise: in boys, a predominantly diaphragmatic type of breathing is established, and in girls, a thoracic type of breathing is established.

Changes in the rhythm and frequency of breathing with age. In newborns and infants, breathing is arrhythmic. Arrhythmicity is expressed in the fact that deep breathing is replaced by shallow breathing, the pauses between inhalations and exhalations 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 - 0.7 - 1 s (in adults - from 1.62 to 5.75 s). From the moment of birth, the same relationship between inhalation and exhalation is established as in adults: inhalation is shorter than exhalation.

The frequency of respiratory movements in children decreases with age. In the fetus it ranges from 46 to 64 per minute. Up to 8 years of age, the respiratory rate (RR) is higher in boys than in girls. By the time of puberty, the respiratory rate in girls becomes greater, and this ratio remains throughout life. By the age of 14–15 years, the respiratory rate approaches the value of an adult.

The respiratory rate in children is much greater than in adults and changes under the influence of various influences. It increases with mental arousal, slight physical exercise, and a slight increase in body and environmental temperature.

Changes in the respiratory and minute volumes of the lungs and their vital capacity with age. The vital capacity of the lungs, tidal and minute volumes in children gradually increase with age due to the growth and development of the chest and lungs.

In a newborn baby, the lungs are inelastic and relatively large. During inhalation, their volume increases slightly, by only 10–15 mm. Providing the child's body with oxygen occurs by increasing the breathing rate. Tidal volume of the lungs increases with age along with a decrease in respiratory rate.

With age absolute value MOR increases, but relative MOR (ratio of MOR to body weight) decreases. In newborns and children of the first year of life it is twice as much as in adults. This is due to the fact that in children, with the same relative tidal volume, the respiratory rate is several times higher than in adults. In this regard, pulmonary ventilation is greater per 1 kg of body weight in children (in newborns it is 400 ml, at 5–6 years of age it is 210, at 7 years of age – 160, at 8–10 years of age – 150, 11 – for 13-year-olds – 130–145, for 14-year-olds – 125, and for 15–17-year-olds – 110). Thanks to this, the growing organism's greater need for O 2 is ensured.

The value of vital capacity increases with age due to the growth of the chest and lungs. In a 5-6 year old child it is 710-800 ml, in a 14-16 year old child it is 2500-2600 ml. From 18 to 25 years of age, the vital capacity of the lungs is maximum, and after 35 to 40 years of age it decreases. The vital capacity of the lungs varies depending on age, height, type of breathing, gender (girls have 100–200 ml less than boys).

In children with physical work breathing changes in a peculiar way. During exercise, the RR increases and the RR remains almost unchanged. Such breathing is uneconomical and cannot ensure long-term performance of work. Pulmonary ventilation in children, when performing physical work, it increases by 2–7 times, and with heavy loads (middle distance running) by almost 20 times. When performing maximum work, girls have less oxygen consumption than boys, especially at 8 - 9 years old and at 16 - 18. All this should be taken into account when practicing physical labor and sports with children of different ages.

The lungs and airways begin to develop in the embryo at 3 weeks from the mesodermal mesenchyme. Subsequently, during the growth process, the lobar structure of the lungs is formed; after 6 months, alveoli are formed. At 6 months, the surface of the alveoli begins to become covered with a protein-lipid lining - surfactant. Its presence is a necessary condition normal lung aeration after birth. If there is a lack of surfactant, after air enters the lungs, the alveoli collapse, which leads to severe breathing problems even without treatment.

The fetal lungs do not function as an organ of external respiration. But they are not in a dormant state; the alveoli and bronchi of the fetus are filled with fluid. The fetus, starting from the 11th week, experiences periodic contractions of the inspiratory muscles - the diaphragm and intercostal muscles.

At the end of pregnancy, fetal breathing movements occupy 30-70% of the total time. The frequency of respiratory movements usually increases at night and in the morning, as well as with increased physical activity of the mother. Breathing movements are necessary for normal development lungs. After they are turned off, the development of alveoli and the increase in lung mass slows down. In addition, the breathing movements of the fetus represent a kind of preparation of the respiratory system for breathing after birth.

Birth causes sudden changes in the state of the respiratory center located in medulla oblongata, leading to the start of ventilation. The first breath occurs, as a rule, after 15-70 seconds. after birth.

The main conditions for the occurrence of the first breath are:

1. Increases in the blood of humoral irritants of the respiratory center, CO 2, H + and lack of O 2;

2. A sharp increase in the flow of sensitive impulses from skin receptors (cold, tactile), proprioceptors, vestibuloreceptors. These impulses activate reticular formation brain stem, which increases the excitability of neurons in the respiratory center;

3. Elimination of sources of inhibition of the respiratory center. Irritation of the receptors located in the nostril area by the liquid greatly inhibits breathing (diver's reflex). Therefore, immediately after the appearance of the fetal head, obstetricians remove mucus and amniotic fluid from the face.

Thus, the occurrence of the first breath is the result simultaneous action a number of factors.

The beginning of pulmonary ventilation is associated with the beginning of the functioning of the pulmonary circulation. Blood flow through the pulmonary capillaries increases sharply. Pulmonary fluid is absorbed from the lungs into the bloodstream, and some of the fluid is absorbed into the lymph.

In children younger age calm breathing - diaphragmatic. This is due to the structural features of the chest. The ribs are located at a greater angle to the spine, so contraction of the intercostal muscles is less effective in changing the volume of the thoracic cavity. The energy cost of a child's breath is much higher than that of an adult. The reason is the narrow airways and their high aerodynamic resistance, as well as the low extensibility of the lung tissue.

Another distinctive feature is more intensive ventilation of the lungs per kilogram of body weight in order to satisfy high level oxidative processes and lower permeability of the pulmonary alveoli for O 2 and CO 2. Thus, in newborns, the respiratory rate is 44 cycles per minute, the tidal volume is 16 ml, and the minute respiratory volume is 720 ml/min. In children 5-8 years of age, the respiratory rate decreases and reaches 25-22 cycles per minute, the tidal volume is 160-240 ml, and the minute respiratory volume is 3900-5350 ml/min. In adolescents, the respiratory rate ranges from 18 to 17 cycles per minute, tidal volume - from 330 to 450 ml, minute respiratory volume - from 6000 to 7700 ml/min. These values ​​are closest to the level of an adult.

With age, the vital capacity of the lungs and the permeability of the pulmonary alveoli for O 2 and CO 2 increase. This is due to an increase in body weight and working muscles, with an increase in the need for energy resources. In addition, breathing becomes more economical, as evidenced by a decrease in respiratory rate and tidal volume.

The greatest morphofunctional changes in the lungs cover the age period up to 7-8 years. At this age there is intense differentiation bronchial tree and an increase in the number of alveoli. An increase in lung volumes is also associated with a change in the diameter of the alveoli. In the period from 7 to 12 years, the diameter of the alveoli doubles, and by adulthood it triples. The total surface of the alveoli increases 20 times.

Thus, the development of the respiratory function of the lungs occurs unevenly. The most intensive development is observed at the ages of 6-8, 10-13, 15-16 years. In these age periods growth and expansion of the tracheobronchial tree predominates. In addition, at this time, the process of differentiation of lung tissue occurs most intensively, which is completed by 8-12 years. Critical periods for the development of functional capabilities of the respiratory system are observed at the ages of 9-10 and 12-13 years.

The stages of maturation of the regulatory functions of the lungs are divided into three periods: 13-14 years (chemoreceptor), 15-16 years (mechanoreceptor), 17 years and older (central). Marked close connection formation of the respiratory system with physical development and maturation of other body systems.

The intensive development of skeletal muscles at the age of 12-16 years affects the nature of age-related changes in the adolescent’s respiratory system. In particular, adolescents with high growth rates often experience delayed development of the respiratory system. Outwardly, this manifests itself in the form of shortness of breath even when performing small tasks. physical activity. Such children complain about fatigue, have low muscle performance, avoid intense activities physical exercise. It is recommended for them gradual increase classes physical culture under the supervision of a doctor.

In contrast, adolescents who play sports have smaller annual height gains and higher lung function. But in general, the development of the respiratory system in the overwhelming majority of children bears the “imprints of civilization.” Low physical activity limits the mobility of the chest. Breathing in this case is superficial, and its physiological value is low. It is necessary to teach children proper and deep breathing, which is a necessary condition for maintaining health and expanding the ability to adapt to physical activity.

Respiratory system.

Age-related characteristics of the respiratory system.

Breathing is a process of constant exchange of gases between the body and the environment, necessary for life. Breathing ensures a constant supply of oxygen to the body, which is necessary for the implementation of oxidative processes, which are the main source of energy. Without access to oxygen, life can last for several minutes. Oxidative processes produce carbon dioxide, which must be removed from the body. Blood is the carrier of oxygen from the lungs to the tissues, and carbon dioxide from the tissues to the lungs.

The act of breathing consists of three processes:

1.External or pulmonary respiration– exchange of gases between the body and the environment.

2. Internal or tissue respiration occurring in cells.

3.Transport of gases by blood, i.e. transfer of oxygen from the blood to the tissues and carbon dioxide from the tissues to the lungs.

The human respiratory system is divided into:

The airways include the nasal cavity, nasopharynx, larynx, trachea, and bronchi.

The respiratory part or lungs - consists of a parenchymal formation, which is divided into alveolar vesicles in which gas exchange occurs.

All parts of the respiratory system undergo significant structural transformations with age, which determines the characteristics of breathing child's body at different stages of development.

The airways and respiratory part begin with the nasal cavity. Air enters through the nostrils, the nasal cavity is divided into two halves, and at the back, with the help of the choanae, it communicates with the nasopharynx. The walls of the nasal cavity are formed by bones and cartilage, lined with mucous membrane. The mucous membrane of the nasal cavity is abundantly supplied with blood vessels and covered with stratified ciliated epithelium.

Passing through the nasal cavity, the air is warmed, moistened and purified. In the nasal cavity there are olfactory bulbs, thanks to which a person perceives smell.

By the time of birth, the child’s nasal cavity is underdeveloped; it is distinguished by narrow nasal openings and the virtual absence of paranasal sinuses, the final formation of which occurs in adolescence. The volume of the nasal cavity increases 2.5 times with age. Structural features of the nasal cavity of children early age make it difficult nasal breathing, children breathe frequently open mouth, which leads to susceptibility to colds. Adenoids may be a factor in this. A “stuffy” nose affects speech - nasal sound. Mouth breathing causes oxygen starvation, congestion in the chest and cranium, deformation of the chest, decreased hearing, frequent otitis media, bronchitis, abnormal (high) development of the hard palate, violation of the nasal septum and shape lower jaw. Connected to the nasal cavity are the airborne sinuses of the adjacent bones - the paranasal sinuses. IN paranasal sinuses nose can develop inflammatory processes: sinusitis - inflammation of the maxillary, maxillary paranasal sinus; Frontal sinusitis is inflammation of the frontal sinus.

From the nasal cavity, air enters the nasopharynx, and then into the oral and laryngeal parts of the pharynx.

The child's pharynx is shorter and wider, as well as the low location of the auditory tube. The structural features of the nasopharynx lead to the fact that diseases of the upper respiratory tract in children are often complicated by inflammation of the middle ear. Disease of the tonsil glands located in the pharynx also seriously affects the health of children. Tonsillitis is inflammation of the tonsils. Adenoids are one of the types of diseases of the tonsil glands - an enlargement of the third tonsil.

The next link in the airways is the larynx. The larynx is located on the front surface of the neck, at the level of 4-6 cervical vertebrae, on both sides of it are the lobes of the thyroid gland, and behind it is the pharynx. The larynx is shaped like a funnel. Its skeleton is formed by paired and unpaired cartilage, connected by joints, ligaments and muscles. Unpaired cartilages - thyroid, epiglottis, cricoid. Paired cartilages – corniculate, arytenoid. The epiglottis covers the entrance to the larynx during swallowing. The inside of the larynx is covered with a mucous membrane with ciliated epithelium. The larynx serves to conduct air and at the same time is an organ of sound production, in which two vocal cords participate, these are mucous folds consisting of elastic connective fibers. The ligaments are stretched between the thyroid and arytenoid cartilages, and limit the glottis.

In children, the larynx is shorter, narrower and higher than in adults. The larynx grows most intensively in the 1-3 years of life and during puberty - in boys an Adam's apple is formed, the vocal cords lengthen, the larynx becomes wider and longer than in girls, and the voice breaks. The mucous membrane of the airways is more abundantly supplied with blood vessels, is tender and vulnerable, and contains fewer mucous glands that protect it from damage.

The trachea extends from the lower edge of the larynx. The trachea is about 12 cm long (its length increases in accordance with the growth of the body, maximum accelerated growth at 14-16 years), consists of cartilaginous half-rings. The posterior wall of the trachea is soft and adjacent to the esophagus. The inside is lined with a mucous membrane containing glands that secrete mucus. From the neck area the trachea passes into chest cavity and is divided into two bronchi, wider and shorter on the left, and narrower and longer on the right. The bronchi enter the lungs and there they divide into bronchi of smaller diameter - bronchioles, which are divided into even smaller ones, forming the bronchial tree, which in turn forms the hilum of the lungs. There are two lungs in the chest cavity; they have the shape of a cone. On the side of each lung facing the heart, there are depressions - the gates of the lung, through which the bronchus, lung nerve, blood and lymphatic vessels. The bronchus branches in each lung. The bronchi, like the trachea, contain cartilage in their walls. The smallest branches of the bronchi are bronchioles; they do not have cartilage, but are equipped with muscle fibers and are capable of narrowing.

The lungs are located in the chest. Every lung is covered serosa– pleura. The pleura consists of two sheets: the parietal sheet is adjacent to the chest, the intranosal sheet is fused with the lung. Between the two sheets there is a space - the pleural cavity, filled with serous fluid, which facilitates the sliding of the pleural sheets during respiratory movements. There is no air in the pleural cavity and the pressure there is negative. The pleural cavity does not communicate with each other.

The right lung consists of three, and the left of two lobes. Every lung department consists of segments: on the right - 11 segments, on the left - 10 segments. Each segment in turn consists of many pulmonary lobes. The structural unit is the acenus - the terminal part of the bronchiole with alveolar vesicles. The bronchioles turn into expansion - alveolar ducts, on the walls of which there are protrusions - alveoli. which are the final part of the respiratory tract. The walls of the pulmonary vesicles consist of a single layer squamous epithelium and capillaries are adjacent to them. Gas exchange occurs through the walls of the alveoli and capillaries: oxygen enters the blood from the alveoli, and carbon dioxide returns back. There are up to 350 million alveoli in the lungs, and their surface reaches 150 m2. The large surface area of ​​the alveoli promotes better gas exchange.

In children, the lungs grow due to an increase in the volume of the alveoli (in newborns, the diameter of the alveoli is 0.07 mm, in adults it reaches 0.2 mm). Increased lung growth occurs up to three years of age. The number of alveoli by the age of 8 reaches the number in an adult. At the age of 3 to 7 years, the growth rate of the lungs is reduced. The alveoli grow especially vigorously after the age of 12; by this age the volume of the lungs increases 10 times compared to a newborn, and by the end of puberty 20 times. Accordingly, gas exchange in the lungs changes, an increase in the total surface of the alveoli leads to an increase in the diffusion capabilities of the lungs.

The exchange of gases between atmospheric air and the air in the alveoli occurs due to the rhythmic alternation of the acts of inhalation and exhalation.

There is no muscle tissue in the lungs, they actively contract, they cannot. The respiratory muscles play an active role in the act of inhalation and exhalation. When they are paralyzed, breathing becomes impossible, although respiratory organs however, they are not affected.

Inhalation is carried out as follows: under the influence of nerve impulses from the chest and diaphragm, the intercostal muscles lift the ribs and move them slightly to the side, thereby increasing the volume of the chest. When the diaphragm contracts, its dome flattens, which also leads to an increase in the volume of the chest. At deep breathing Other muscles of the chest and neck also take part. The lungs are located in a hermetically sealed chest and move passively behind its moving walls, since they are attached to the chest with the help of the pleura. This is facilitated by negative pressure in the chest. When you inhale, the lungs stretch, the pressure in them drops and becomes below atmospheric pressure, and outside air rushes into the lungs. When you exhale, the muscles relax, the ribs drop, the volume of the chest decreases, the lungs contract, the pressure in them increases and air rushes out. The depth of inspiration depends on the expansion of the chest during inhalation. The condition of the lung tissue is very important for the act of breathing. which has elasticity i.e. lung tissue has a certain resistance to stretching.

As the musculoskeletal apparatus of the respiratory system matures, and the characteristics of its development in boys and girls determine age and gender differences in breathing types. In young children, the ribs have a slight bend and occupy an almost horizontal position. The upper ribs and shoulder girdle are located high, the intercostal muscles are weak. In this regard, newborns breathe diaphragmatically. As the intercostal muscles develop and the child grows, the chest goes down, the ribs take an oblique position - the child’s breathing becomes thoraco-abdominal with a predominance of the diaphragmatic. At the age of 3 to 7 years, chest breathing predominates. And at the age of 7-8 years, gender differences in the type of breathing are revealed. In boys, the abdominal type predominates, and in girls, the thoracic type predominates. Sexual differentiation ends by the age of 14-17 years. The types of breathing in boys and girls can change depending on sports and work activity.

Age-related features of the structure of the chest and muscles determine the features of the depth and frequency of breathing in childhood. IN calm state an adult makes 16-20 breathing movements per minute, 500 ml is inhaled per breath. air. The volume of air characterizes the depth of breathing.

The newborn's breathing is rapid and shallow. In children of the first year of life, the respiratory rate is 50-60 respiratory movements per minute, 1-2 years 30-40 respiratory movements per minute, 2-4 years 25-35 respiratory movements per minute, 4-6 years 23-26 respiratory movements per minute. In school-age children, there is a further decrease in the breathing rate, 18-20 respiratory movements per minute. The high frequency of respiratory movements in a child ensures high ventilation of the lungs. The volume of exhaled air in a child at 1 month of life is 30 ml, at 1 year - 70 ml, at 6 years - 156 ml, at 10 years - 240 ml, at 14 years - 300 ml. Minute breathing volume - This is the amount of air that a person exhales in 1 minute; the more often the breath, the higher the minute volume.

An important characteristic of the functioning of the respiratory system is the vital capacity of the lungs (VC) - greatest number air that a person can exhale after taking a deep breath. Vital capacity changes with age and depends on body length, the degree of development of the chest and respiratory muscles, and gender. At calm breathing In one breath, about 500 cm 3 of air enters the lungs - respiratory air. With maximum inhalation after a quiet exhalation, an average of 1500 cm 3 of air enters the lungs more than with a quiet inhalation - additional volume. With maximum exhalation after a normal inhalation, 1500 cm 3 more air can come out of the lungs than during a normal exhalation - the reserve volume. All these three types of volume - respiratory, additional, reserve - together make up vital capacity: 500 cm 3 +1500 cm 3 +1500 cm 3 = 3500 cm 3. After exhalation, even the deepest, about 100 cm 3 of air remains in the lungs - residual air, it remains even in the lungs of a corpse, a breathing child or an adult. Air enters the lungs with the first breath after birth. Vital vital capacity is determined using a special device - a spirometer. Typically, vital capacity is greater in men than in women. Trained people have a higher vital capacity than untrained people. A child's vital capacity can be determined with his conscious participation only after 4-5 years.

Regulation of breathing is carried out by the central nervous system, special areas of which determine automatic breathing - alternating inhalation and exhalation and voluntary breathing, providing adaptive changes in the respiratory system that correspond to the situation and type of activity. The activity of the respiratory center is regulated reflexively, by impulses coming from various receptors and humorally.

The breathing center is a group nerve cells, which are located in the medulla oblongata, its destruction leads to respiratory arrest. In the respiratory center there are two sections: the inhalation section and the exhalation section, the functions of which are interconnected. When the inhalation department is excited, the exhalation department is inhibited and vice versa.

Special clusters of nerve cells in the pons and diencephalon are involved in the regulation of breathing. IN spinal cord there is a group of cells whose processes go into the spinal nerves to the respiratory muscles. In the respiratory center, excitation alternates with inhibition. When you inhale, the lungs expand and their walls stretch, which irritates the endings of the vagus nerve. Excitation is transmitted to the respiratory center and inhibits its activity. The muscles stop receiving stimulation from the respiratory center and relax, the chest drops, its volume decreases, and exhalation occurs. When relaxed, the centripetal fibers vagus nerve cease to be excited, and the respiratory center does not receive inhibitory impulses; it becomes excited again - another inhalation occurs. In this way, self-regulation occurs: inhalation causes exhalation, and exhalation causes inhalation.

The activity of the respiratory center is also regulated humorally, changing depending on the chemical composition of the blood. The reason for changes in the activity of the respiratory center is the concentration of carbon dioxide in the blood. It is a specific respiratory stimulant: an increase in the concentration of carbon dioxide in the blood leads to stimulation of the respiratory center - breathing becomes frequent and deep. This continues until the level of carbon dioxide in the blood decreases to normal. The respiratory center responds to a decrease in the concentration of carbon dioxide in the blood by decreasing excitability until it completely stops its activity for some time. The leading physiological mechanism affecting the respiratory center is reflex, followed by humoral. Breathing is subordinate to the cerebral cortex, as evidenced by the fact of voluntary holding of breath or changes in the frequency and depth of breathing, increased breathing during emotional states of a person.

Description of work

Breathing is a process of constant exchange of gases between the body and environment. Breathing ensures a constant supply of oxygen to the body, which is necessary for the implementation of oxidative processes, which are the main source of energy. Without access to oxygen, life can last for several minutes.

2. Structure, functions and age-related characteristics of the airways (nasal cavity, larynx, trachea, bronchi)………………………………………………………3

5. The mechanism of inhalation and exhalation…………………………………………… …….....11

General characteristics and age characteristics
respiratory system

Structure, functions and age characteristics
airways (nasal cavity, larynx, trachea, bronchi)

Structure, functions and age-related characteristics of the lungs

Breathing regulation