§2. Ministry of Public Education of the Republic of Uzbekistan Navoi State Pedagogical Institute Department: fundamentals of medical knowledge §2. Regulation of breathing and its age-related features

Topic No. 11 AGE FEATURES OF THE RESPIRATORY ORGANS. HYGIENIC REQUIREMENTS FOR THE AIR ENVIRONMENT OF EDUCATIONAL PREMISES. STRUCTURE AND FUNCTIONS OF THE RESPIRATORY ORGANS AND THEIR AGE FEATURES.

Plan:

1.Development of the respiratory system in children.

2. Mechanism of the first breath.

3.Functional features of the respiratory system in children.

4.Respiration regulation and its age-related characteristics.

Literatures:

1.A.V Mazurin. Propaedeutics of childhood diseases 1986.

2. A.G. Khripkova. Age physiology and school hygiene 1989.

3. B. Aminov. Man and his health. 1997

4 Popular Medical Encyclopedia 1985.

1.Development of the respiratory system in children. By the end of the 3rd to 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; At the caudal end, a flask-shaped expansion appears, which at the 4th week is divided into the right and left parts (the future right and left lungs). At the 6th week, lobar bronchi are formed, at the 8-10th week - segmental bronchi. From the 16th week, respiratory bronchioles are formed. From the 24th week – the formation of future acini.

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

The meaning of breathing. 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 only a few minutes. Oxidative processes produce carbon dioxide, which must be removed from the body.

The concept of breathing includes the following processes:

1) external respiration - exchange of gases between the external environment and the lungs - pulmonary ventilation; 2) exchange of gases in the lungs between alveolar air and capillary blood - pulmonary respiration; 3) transport of gases by blood, transfer of oxygen from the lungs to tissues and carbon dioxide from tissues to the lungs; 4) exchange of gases in tissues; 5) internal, or tissue, respiration - biological processes occurring in the mitochondria of cells. The human respiratory system includes: airways, which include the nasal cavity, nasopharynx, larynx, trachea, bronchi; lungs - consisting of bronchioles, alveolar sacs and richly supplied with vascular branches; the musculoskeletal system that provides respiratory movements: this includes the ribs, intercostal and other auxiliary muscles, and the diaphragm. All parts of the respiratory system undergo significant structural transformations with age, which determines the breathing characteristics of the child’s body at different stages of development, the airways and the respiratory tract begin nasal cavity. The mucous membrane of the nasal cavity is abundantly supplied with blood vessels and covered with stratified ciliated epithelium. The epithelium contains many glands that secrete mucus, which, together with dust particles penetrated with inhaled air, is removed by the flickering movements of the cilia. In the nasal cavity, the inhaled air is warmed, partially cleared of dust and moistened. At 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 approximately 2.5 times with age. The structural features of the nasal cavity of young children make nasal breathing difficult; children often breathe with their mouths open, which leads to susceptibility to colds. One of the factors that makes breathing through the nose difficult is the adenoids. A “stuffy” nose affects speech, causing a closed nasal tone and tongue-tiedness. With a “stuffy” nose, the air is not sufficiently cleared of harmful impurities, dust, and is not sufficiently moistened, which causes frequent inflammation of the larynx and trachea. Mouth breathing causes oxygen starvation, congestion in the chest and cranium, deformation of the chest, decreased hearing, frequent otitis media, bronchitis, dryness of the oral mucosa, abnormal (high) development of the hard palate, disruption of the normal position of the nasal septum and the shape of the lower jaw. Inflammatory processes can develop in the paranasal sinuses of the nasal cavity of children - sinusitis and frontal sinusitis. Sinusitis - inflammation of the paranasal (maxillary - maxillary) nasal cavity. Typically, sinusitis develops after an acute infection (scarlet fever, measles, influenza). The infection enters through blood from the nasal cavity or from a neighboring lesion (carious tooth). The patient experiences general malaise, chills, the temperature rises to 38° in the first days of the disease, a headache or neuralgic pain appears radiating to the cheek, upper teeth and temple, the nasal mucosa (unilaterally) swells, discharge appears (on the same side) . It is necessary to immediately send the child to a medical facility for timely treatment. Insufficient treatment leads to the disease becoming chronic.

Frontit- inflammation of the frontal sinus. The patient complains of pain above the eyebrow, in the forehead and the lower wall of the frontal sinus, lacrimation and photophobia are observed. The complex of these symptoms appears periodically, they continue from 10-11 am and subside by 15-16 pm. When the body is in an upright position, copious discharge (purulent) is observed. It is important to refer the child to a medical facility for timely treatment. Often the disease becomes chronic. Air enters the nasal cavity nasopharynx- upper part of the pharynx. The nasal cavity, larynx, and auditory tubes, which connect the pharyngeal cavity to the middle ear, also open into the pharynx. The child's pharynx is shorter, wider and has a lower 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, since the infection easily penetrates the ear through the wide and short auditory tube. Diseases of the tonsil glands located in the pharynx. Tonsillitis- tonsillitis. It can be acute (angina) and chronic. Chronic tonsillitis develops after frequent tonsillitis and some other infectious diseases accompanied by inflammation of the mucous membrane of the pharynx (scarlet fever, measles, diphtheria). Microbial (streptococcus and adenovirus) infection plays a special role in the development of chronic tonsil disease. Chronic tonsillitis contributes to the occurrence of rheumatism, inflammation of the kidneys, and organic damage to the heart.

One of the types of diseases of the tonsil glands is adenoids - an enlargement of the third tonsil located in the nasopharynx. For the enlargement of the tonsil, a number of past infections and climatic conditions are important (in cold climates, adenoids in children are more common than in warm climates). Enlargement of the tonsil is observed mainly in children under 7-8 years of age. With adenoids, the following are observed: a long-lasting runny nose, difficulty nasal breathing, especially at night (snoring, unrefreshing, restless sleep with frequent awakenings), dullness of smell, an open mouth, causing the lower lip to droop, nasolabial folds smooth out, a special “adenoid” expression appears faces. The next link of the airways is larynx. The skeleton of the larynx is formed by cartilage, connected by joints, ligaments and muscles. The laryngeal cavity is covered with a mucous membrane, which forms two pairs of folds that close the entrance to the larynx during swallowing. The lower pair of folds cover the vocal cords. The space between the vocal cords is called glottis. T Thus, the larynx not only connects the pharynx with the trachea, but also participates in speech function. The larynx in children is shorter, narrower and located higher than in adults. The larynx grows most intensively in the 1st-3rd years of life and during puberty. During puberty, gender differences appear in the structure of the larynx. In boys, an Adam's apple forms, the vocal cords lengthen, the larynx becomes wider and longer than in girls, and the voice breaks. The lower edge of the larynx departs trachea. Its length increases in accordance with the growth of the body; the maximum acceleration of tracheal growth is noted at the age of 14-16 years. The circumference of the trachea increases according to the increase in the volume of the chest. The trachea branches into two bronchus, the right one is shorter and wider. The greatest growth of the bronchi occurs in the first year of life and during puberty.

The mucous membrane of the airways in children is more abundantly supplied with blood vessels, is tender and vulnerable, it contains fewer mucous glands that protect it from damage. These features of the mucous membrane lining the airways in childhood, combined with a narrower lumen of the larynx and trachea, make children susceptible to inflammatory diseases of the respiratory system.

Lungs. With age, the structure of the main respiratory organ - the lungs - changes significantly. The primary bronchus, having entered the gates of the lungs, is divided into smaller bronchi, which form the bronchial tree. The thinnest branches are called bronchioles. Thin bronchioles enter the pulmonary lobules and within them are divided into terminal bronchioles.

Bronchioles branch into alveolar ducts with sacs, the walls of which are formed by many pulmonary vesicles - alveoli The alveoli are the final part of the respiratory tract. The walls of the pulmonary vesicles consist of a single layer of squamous epithelial cells. Each alveolus is surrounded

Outside there is a dense network of capillaries. Gases are exchanged through the walls of the alveoli and capillaries - oxygen passes from the air into the blood, and carbon dioxide and water vapor enter the alveoli from the blood.

There are up to 350 million alveoli in the lungs, and their surface reaches 150 m. The large surface of the alveoli promotes better gas exchange. On one side of this surface there is alveolar air, constantly renewed in its composition, on the other - blood continuously flowing through the vessels. Diffusion of oxygen and carbon dioxide occurs through the extensive surface of the alveoli. During physical work, when the alveoli stretch significantly during deep entrances, the size of the respiratory surface increases. The larger the total surface of the alveoli, the more intense the diffusion of gases.

Each lung is covered by a serous membrane called pleura. The pleura has two layers. One is tightly fused to the lung, the other is attached to the chest. Between both leaves there is a small pleural cavity, filled with serous fluid (about 1-2 ml), which facilitates the sliding of the pleura during respiratory movements. Gas exchange takes place in the alveoli: oxygen from the alveolar air passes into the blood, and carbon dioxide enters the alveoli from the blood.

The walls of the alveoli and the walls of the capillaries are very thin, which facilitates the penetration of gases from the lungs into the blood and vice versa. Gas exchange depends on the surface through which gases diffuse and the difference in partial pressure of the diffusing gases. Such conditions exist in the lungs. With a deep breath, the alveoli stretch and their surface reaches 100-150 m. The surface of the capillaries in the lungs is also large. There is also a sufficient difference in the partial pressure of gases, alveolar air and the tension of these gases in the venous blood. For oxygen, this difference is 70 mmHg. Art., for carbon dioxide - 7 mm Hg. Art.

The lungs in children grow mainly due to an increase in the volume of the alveoli (in a newborn, the diameter of the alveoli is 0.07 mm, in an adult it already reaches 0.2 mm). Up to 3 years of age, increased growth of the lungs and differentiation of their individual elements occurs. The number of alveoli by the age of 8 reaches the number in an adult. Between the ages of 3 and 7 years, the rate of lung growth decreases. Alveoli grow especially vigorously after 12 years of age. By the age of 12, the volume of the lungs increases 10 times compared to the volume of the lungs of a newborn, and by the end of puberty - 20 times (mainly due to an increase in the volume of the alveoli). 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.

Breathing movements. 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, and therefore they cannot actively contract. The respiratory muscles play an active role in the act of inhalation and exhalation. When the respiratory muscles are paralyzed, breathing becomes impossible, although the respiratory organs are not affected.

When inhaling, the external intercostal muscles and the diaphragm contract. The intercostal muscles lift the ribs and move them slightly to the side. The volume of the chest increases. When the diaphragm contracts, its dome flattens, which also leads to an increase in the volume of the chest. When breathing deeply, other muscles of the chest and neck are also involved. The lungs, being in a hermetically sealed chest, passively follow its moving walls during inhalation and exhalation, since they are attached to the chest with the help of the pleura. This is also facilitated by negative pressure in the chest cavity. Negative pressure is pressure below atmospheric pressure. During inhalation it is 9-12 mmHg below atmospheric. Art., and during exhalation - by 2-6 mm Hg. Art.

During development, the chest grows faster than the lungs, which is why the lungs are constantly (even when exhaling) stretched. The stretched elastic tissue of the lungs tends to shrink. The force with which lung tissue tends to compress due to elasticity is counteracted by atmospheric pressure. Around the lungs, in the pleural cavity, a pressure equal to atmospheric pressure minus the elastic traction of the lungs is created. This creates negative pressure around the lungs. Due to the negative pressure in the pleural cavity, the lungs follow the expanding chest. The lungs are stretched. Atmospheric pressure acts on the lungs from the inside through the airways, stretches them, and presses them against the chest wall.

In a distended lung, the pressure becomes lower than atmospheric pressure, and due to the pressure difference, atmospheric air rushes through the respiratory tract into the lungs. The more the volume of the chest increases during inhalation, the more the lungs stretch, the deeper the inhalation.

■ When the respiratory muscles relax, the ribs lower to their original position, the dome of the diaphragm rises, the volume of the chest, and therefore the lungs, decreases and the air is exhaled out. The abdominal muscles, internal intercostal and other muscles take part in deep exhalation. The gradual maturation of the musculoskeletal apparatus of the respiratory system 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 the entire shoulder girdle are located high, the intercostal muscles are weak. Due to these characteristics, in newborns it is predominant diaphragmatic breathing with minor involvement of the intercostal muscles. The diaphragmatic type of breathing persists until the second half of the first year of life. As the intercostal muscles develop and the child grows, the chest moves down and the ribs take on an oblique position. Gradually, the breathing of infants becomes abdominal, with a predominance of the diaphragmatic, and in the upper part of the chest the mobility remains small. At the age of 3 to 7 years, due to the development of the shoulder girdle, the chest type of breathing, and by the age of 7 it becomes pronounced.

At 7-8 years old, gender differences in the type of breathing are revealed: In boys it becomes predominant abdominal type of breathing, for girls - chest. Sexual differentiation of breathing ends by the age of 14-17 years. It should be noted that the type of breathing in boys and girls can change depending on sports and work activities.

Age-related characteristics of the structure of the chest and muscles determine the characteristics of the depth and frequency of breathing in childhood. An adult makes an average of 15-16 breathing movements per minute, and 500 ml of air is inhaled in one breath during quiet breathing. The volume of air entering the lungs in one breath characterizes the depth of breathing.

The breathing of a newborn baby is frequent and shallow. The frequency is subject to significant fluctuations of 48-63 respiratory cycles per minute during sleep. In children of the first year of life, the frequency of respiratory movements per minute during wakefulness is 50-60, and during sleep - 35-40. In children 1-2 years old, during wakefulness, the respiratory rate is 35-40, in 2-4 year olds - 25-35, and in 4-6 year olds - 23-26 cycles per minute. In school-age children, breathing decreases further (18-20 times per minute).

The high frequency of respiratory movements in a child ensures high pulmonary ventilation.

The volume of inhaled 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 - 239 ml, at 14 years - 300 ml.

Due to the high breathing rate in children, the minute volume of breathing (in terms of 1 kg of weight) is significantly higher than in adults. Minute breathing volume- this is the amount of air that a person inhales in 1 minute; it is determined by the product of the amount of inhaled air and the number of respiratory movements in 1 minute. In a newborn, the minute breathing volume is 650-700 ml of air, by the end of the first year of life - 2600-2700 ml, by 6 years - 3500 ml, in a 10-year-old child - 4300 ml, in a 14-year-old child - 4900 ml, in an adult person - 5000-6000 ml. An important characteristic of the functioning of the respiratory system is vital capacity lungs - the largest amount of air that a person can exhale after a deep breath. The vital air capacity of the lungs changes with age (Table 18) and depends on body length, the degree of development of the chest and respiratory muscles, and gender. It is usually greater in men than in women. Athletes have a larger vital capacity than untrained people: for weightlifters, for example, it is about 4000 ml, for football players - 4200, for gymnasts - 4300, for swimmers - 4900, for rowers - 5500 ml or more.

Since measuring the vital capacity of the lungs requires the active and conscious participation of the child himself, it can be determined only after 4-5 years.

By the age of 16-17 years, the vital capacity of the lungs reaches values ​​characteristic of an adult. A spirometer is used to determine the vital capacity of the lungs. Vital capacity is an important indicator of physical development.

Average vital capacity of the lungs (in ml)

REGULATION OF BREATHING AND ITS AGE FEATURES

Respiratory center. Regulation of breathing is carried out by the central nervous system, special areas of which determine automatic breathing - alternating inhalation and exhalation and arbitrary breathing, providing adaptive changes in the respiratory system corresponding to a specific external situation and activity. The group of nerve cells responsible for the respiratory cycle is called respiratory center. The respiratory center is located in the medulla oblongata, its destruction leads to respiratory arrest. The respiratory center is in a state of constant activity: excitation impulses arise rhythmically in it. These impulses arise automatically. Even after the centripetal pathways leading to the respiratory center are completely turned off, rhythmic activity can be registered in it. The automaticity of the respiratory center is associated with the metabolic process in it. Rhythmic impulses are transmitted from the respiratory center through centrifugal neurons to the intercostal muscles and diaphragm, ensuring a sequential alternation of inhalation and exhalation. The activity of the respiratory center is regulated reflexively, by impulses coming from various receptors, and humorally, changing depending on the chemical composition of the blood.

Reflex regulation. Receptors, the excitation of which enters the respiratory center along centripetal pathways, include chemoreceptors, located in large vessels (arteries) and responding to a decrease in oxygen tension in the blood and an increase in the concentration of carbon dioxide, and mechanoreceptors lungs and respiratory muscles. The regulation of breathing is also influenced by the receptors of the airways. The receptors of the lungs and respiratory muscles are of particular importance in the alternation of inhalation and exhalation; the ratio of these phases of the respiratory cycle, their depth and frequency, largely depends on them. When you inhale, when the lungs stretch, the receptors in their walls are irritated. Impulses from the lung receptors along the centripetal fibers of the vagus nerve reach the respiratory center, inhibit the inhalation center and excite the exhalation center. As a result, the respiratory muscles relax, the chest drops, the diaphragm takes the form of a dome, the volume of the chest decreases and exhalation occurs. Exhalation, in turn, reflexively stimulates inhalation. The cerebral cortex takes part in the regulation of breathing, providing the finest adaptation of breathing to the needs of the body in connection with changes in environmental conditions and the vital functions of the body. A person can arbitrarily, at will, hold his breath for a while, change the rhythm and depth of breathing movements. The influences of the cerebral cortex explain the pre-start changes in breathing in athletes - a significant deepening and increased breathing before the start of the competition. It is possible to develop conditioned breathing reflexes. If you add 5-7% carbon dioxide to the inhaled air, which in such a concentration speeds up breathing, and accompany the inhalation with the sound of a metronome or a bell, then after several combinations the bell or sound of a metronome alone will cause increased breathing.

Humoral influences on the respiratory center. The chemical composition of the blood, in particular its gas composition, has a great influence on the state of the respiratory center. The accumulation of carbon dioxide in the blood irritates the receptors in the blood vessels carrying blood to the head and reflexively stimulates the respiratory center. Other acidic products entering the blood act in a similar way, for example lactic acid, the content of which in the blood increases during muscle work. Features of breathing regulation in childhood. By the time a child is born, his respiratory center is able to ensure a rhythmic change in the phases of the respiratory cycle (inhalation and exhalation), but not as perfectly as in older children. This is due to the fact that at the time of birth the functional formation of the respiratory center has not yet completed. This is evidenced by the great variability in the frequency, depth, and rhythm of breathing in young children. The excitability of the respiratory center in newborns and infants is low. Children in the first years of life are more resistant to oxygen deficiency (hypoxia) than older children.

The formation of the functional activity of the respiratory center occurs with age. By the age of one, the ability to adapt breathing to various living conditions is already well expressed. The sensitivity of the respiratory center to carbon dioxide increases with age and at school age reaches approximately the level of adults. It should be noted that during puberty, temporary disturbances in the regulation of breathing occur and the body of adolescents is less resistant to oxygen deficiency than the body of an adult. The need for oxygen, which increases as the body grows and develops, is ensured by improved regulation of the respiratory apparatus, leading to an increasing economization of its activity. As the cerebral cortex matures, the ability to voluntarily change breathing improves - to suppress respiratory movements or produce maximum ventilation of the lungs. In an adult, during muscular work, pulmonary ventilation increases due to increased and deepening breathing. Activities such as running, swimming, skating, skiing, and cycling dramatically increase the volume of pulmonary ventilation. In trained people, pulmonary gas exchange increases mainly due to an increase in the depth of breathing. Children, due to the characteristics of their breathing apparatus, cannot significantly change the depth of breathing during physical exertion, but rather increase their breathing speed. The already frequent and shallow breathing in children during physical activity becomes even more frequent and shallow. This results in lower ventilation efficiency, especially in young children. The body of a teenager, unlike an adult, quickly reaches the maximum level of oxygen consumption, but also stops working faster due to the inability to maintain oxygen consumption at a high level for a long time. Voluntary changes in breathing play an important role when performing a number of breathing exercises and help to correctly combine certain movements with the breathing phase (inhalation and exhalation). One of the important factors in ensuring optimal functioning of the respiratory system under various types of loads is the regulation of the ratio of inhalation and exhalation. The most effective and facilitating physical and mental activity is the respiratory cycle, in which the exhalation is longer than the inhalation. Teaching children to breathe correctly when walking, running and other activities is one of the teacher’s tasks. One of the conditions for proper breathing is taking care of the development of the chest. For this, correct body position is important, especially while sitting at a desk, breathing exercises and other physical exercises that develop the muscles that move the chest. Particularly useful in this regard are sports such as swimming, rowing, skating, and skiing.

Typically, a person with a well-developed chest breathes evenly and correctly. It is necessary to teach children to walk and stand with a straight posture, as this helps expand the chest, facilitates the functioning of the lungs and ensures deeper breathing. When the body is bent, less air enters the body.

The correct position of the body of children during various activities helps to expand the chest and facilitates deep breathing. On the contrary, when the body is bent, the opposite conditions are created, the normal activity of the lungs is disrupted, they absorb less air, and at the same time oxygen.

Much attention is paid in the process of physical education to the education of children and adolescents in proper breathing through the nose in a state of relative rest, during work activity and performing physical exercises. Breathing exercises, swimming, rowing, skating, and skiing especially help improve breathing.

Breathing exercises also have great health benefits. When you inhale calmly and deeply, intrathoracic pressure decreases as the diaphragm moves down. The flow of venous blood to the right atrium increases, which facilitates the work of the heart. The diaphragm, which descends during inhalation, massages the liver and upper abdominal organs, helps remove metabolic products from them, and from the liver - venous stagnant blood and bile.

During deep exhalation, the diaphragm rises, which increases the outflow of venous blood from the lower extremities, pelvis and abdomen. As a result, blood circulation is facilitated. At the same time, with a deep exhalation, a light massage of the heart occurs and its blood supply improves. In breathing exercises there are three main types of breathing, called according to the form of execution - chest, abdominal and full breathing. Considered to be the most beneficial for health full breath. There are various breathing exercises. It is recommended to perform these complexes up to 3 times a day, at least an hour after meals. Hygienic importance of indoor air. Air purity and its physical and chemical properties are of great importance for the health and performance of children and adolescents. Staying children and adolescents in a dusty, poorly ventilated room causes not only a deterioration in the functional state of the body, but also many diseases. It is known that in closed, poorly ventilated and aerated rooms, simultaneously with an increase in air temperature, its physicochemical properties sharply deteriorate. The human body is not indifferent to the content of positive and negative ions in the air. In atmospheric air, the number of positive and negative ions is almost equal, light ions significantly predominate over heavy ones.

Studies have shown that light and negative ions have a beneficial effect on humans, and their number in work areas is gradually decreasing. Positive and heavy ions begin to predominate, which depress human life. In parallel with the deterioration of the ionic composition, the increase in temperature and humidity in classrooms, the concentration of carbon dioxide increases, ammonia and various organic substances accumulate. The deterioration of the physico-chemical properties of air, especially in rooms with a reduced height, entails a significant deterioration in the performance of cells in the human cerebral cortex. From the beginning to the end of classes, the dustiness of the air and its bacterial contamination increases, especially if wet cleaning and ventilation of the premises were poorly carried out before the start of classes. The number of colonies of microorganisms in 1 m3 of air in such conditions by the end of classes in the second shift increases 6-7 times, along with harmless microflora it also contains pathogenic ones.

High temperatures in classrooms (up to 26°) lead to stress on thermoregulatory processes and decreased performance. In such conditions, the mental performance of students by the end of lessons decreases sharply. The influence of temperature conditions on the performance of students during physical education and labor is even more clearly evident.

In the premises of schools, boarding schools, boarding schools at schools, with a relative humidity of 40-60% and an air velocity of no more than 0.2 m/s, its temperature is normalized in accordance with the climatic regions. The difference in air temperature in the room both vertically and horizontally set within 2-3°C. The low air temperature in the gym, workshops and recreational premises corresponds to the type of activity of children and adolescents in these premises.

During classes, special care should be taken about the thermal comfort of students sitting in the first row from the windows, strictly observe the established gaps, and do not seat children near radiators (stoves). In schools with strip glazing, the gaps between the first row of desks and the windows in winter should be increased to 1.0-1.2 m. Due to the low thermal resistance of glass and the high air permeability of window frames, the large glazed surface of the outer wall in winter becomes a source of powerful radiation and convection cooling. Already at an outside air temperature below -15°C, the temperature of the inner surface of the glass drops to an average of 6-10°C, and under the influence of wind to 0°C.

Hygienic requirements To heating schools.

Of the existing central heating systems in children's institutions, a low-pressure water heating system is used. This heating, when using devices with large heat capacity, ensures uniform air temperature in the room throughout the day, does not make the air too dry and eliminates the sublimation of dust on heating devices. Dutch ovens, which have a high heat capacity, are used as local heating appliances. The furnaces are fired from the corridors at night, and the pipes are closed no later than 2 hours before the students arrive.

MINISTRY OF HEALTH OF THE REPUBLIC OF UZBEKISTAN

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TASHKENT MEDICAL ACADEMY

DEPARTMENT OF NORMAL, PATHOLOGICAL PHYSIOLOGY AND PATHOLOGICAL ANATOMY FOR STUDENTS OF DENTAL AND MEDICAL-PEDAGOGICAL FACULTIES

Lecture No. 8

SUBJECT: “AGE FEATURES OF BREATHING PHYSIOLOGY”

Tashkent - 2010

Lecture outline:

1. External and internal breathing. Lung volumes

2.Gas exchange in the lungs

3.Transport of gases by blood. Breathing regulation

4. Age-related changes in breathing

5.Respiratory hygiene

Purpose of the lecture: teaching students classical information in the field of respiratory physiology, basic methods of studying the respiratory system and methods of artificial respiration.

In the human and animal bodies, oxygen reserves are limited. Therefore, the body needs a continuous supply of oxygen from the environment. Carbon dioxide must also be constantly and continuously removed from the body, which is always formed during the metabolic process and is a toxic compound in large quantities.

Breathing is a complex continuous process, as a result of which the gas composition of the blood is constantly updated. This is its essence.

In the process of breathing, it is customary to distinguish three parts: external, or pulmonary, respiration, gas transport by blood and internal, or tissue, respiration.

External respiration is the exchange of gases between the body and the atmospheric air surrounding it. External respiration can be divided into two stages - the exchange of gases between atmospheric and alveolar air and the gas exchange between the blood of the pulmonary capillaries and the alveolar air. External respiration is carried out due to the activity of the external respiration apparatus.

The external respiration apparatus includes the airways, lungs, pleura, the skeleton of the chest and its muscles, as well as the diaphragm. The main function of the external respiration apparatus is to provide the body with oxygen and relieve it of excess carbon dioxide. The functional state of the external respiration apparatus can be judged by the rhythm, depth, frequency of breathing, the size of the lung volumes, the indicators of oxygen absorption and carbon dioxide release, etc.

Transport of gases is carried out by blood. It is provided by the difference in partial pressure (tension) of gases along their path: oxygen from the lungs to the tissues, carbon dioxide from the cells to the lungs.

Internal or tissue respiration can also be divided into two stages. The first stage is the exchange of gases between blood and tissues. The second is the consumption of oxygen by cells and the release of carbon dioxide by them (cellular respiration).

A person breathes atmospheric air, which has the following composition: 20.94% oxygen, 0.03% carbon dioxide, 79.03% nitrogen. Exhaled air contains 163% oxygen, 4% carbon dioxide, and 79.7% nitrogen.

The composition of exhaled air is not constant and depends on the intensity of metabolism, as well as on the frequency and depth of breathing. As soon as you hold your breath or make several deep breathing movements, the composition of the exhaled air changes.

Alveolar air differs in composition from atmospheric air, which is quite natural. In the alveoli, gases are exchanged between air and blood, while oxygen diffuses into the blood, and carbon dioxide diffuses out of the blood. As a result, the oxygen content in the alveolar air sharply decreases and the amount of carbon dioxide increases. The percentage of individual gases in the alveolar air: 14.2-14.6% oxygen, 5.2-5.7% carbon dioxide, 79.7-80% nitrogen. Alveolar air differs in composition from exhaled air. This is explained by the fact that the exhaled air contains a mixture of gases from the alveoli and harmful space.

Each lung is covered on the outside with a serous membrane-pleura, consisting of two layers: parietal and pulmonary (visceral). Between the layers of the pleura there is a narrow gap filled with serous fluid, the pleural cavity. Normally, there is no cavity, but it can occur if the layers of the pleura are pushed apart by exudate that forms in some pathological conditions, or by air, for example, during a chest injury.

Negative intrathoracic pressure and its increase during inspiration have great physiological significance. Due to negative pressure, the alveoli are always in a stretched state, which significantly increases the respiratory surface of the lungs, especially during inhalation. Negative intrathoracic pressure plays a significant role in hemodynamics, ensuring venous return of blood to the heart and improving blood circulation in the pulmonary circle, especially during the inhalation phase. The suction effect of the chest also promotes lymph circulation.

The respiratory cycle consists of inhalation, exhalation and a respiratory pause. Usually the inhalation is shorter than the exhalation. The duration of inhalation in an adult is from 0.9 to 4.7 s, the duration of exhalation is 1.2-6 s. The duration of inhalation and exhalation depends mainly on reflex effects coming from the receptors of the lung tissue. The respiratory pause is a variable component of the respiratory cycle. It varies in size and may even be absent.

Respiratory movements occur with a certain rhythm and frequency, which are determined by the number of chest excursions per minute. In an adult, the respiratory rate is 12-18 per minute. In children, breathing is shallow and therefore more frequent than in adults. So, a newborn breathes about 60 times per minute, a 5-year-old child 25 times per minute. At any age, the frequency of respiratory movements is 4-5 times less than the number of heartbeats.

The frequency and depth of breathing is influenced by many factors, in particular the emotional state, mental stress, changes in the chemical composition of the blood, the degree of fitness of the body, the level and intensity of metabolism.

Inhalation mechanism. Inhalation (inspiration) occurs due to an increase in the volume of the chest in three directions - vertical, sagittal (antero-posterior) and frontal (costal). The change in the size of the chest cavity occurs due to contraction of the respiratory muscles.

Depending on the predominant participation of the muscles of the chest and diaphragm in the act of inhalation, thoracic, or costal, and abdominal, or diaphragmatic, types of breathing are distinguished. In men, the abdominal type of breathing predominates, in women - thoracic.

As you inhale, the lungs passively follow the expanding chest. The respiratory surface of the lungs increases, but the pressure in them decreases and becomes 0.26 kPa (2 mm Hg. cTA below atmospheric). This promotes the flow of air through the airways into the lungs. The glottis prevents rapid equalization of pressure in the lungs, since the airways in this place are narrowed. Only at the height of inspiration does the dilated alveoli become completely filled with air.

Exhalation (expiration) occurs as a result of relaxation of the external intercostal muscles and raising of the dome of the diaphragm. In this case, the chest returns to its original position and the respiratory surface of the lungs decreases. The narrowing of the airways in the area of ​​the glottis causes the slow release of air from the lungs - At the beginning of the exhalation phase, the pressure in the lungs becomes 3-4 mm Hg. Art. above atmospheric, which facilitates the release of air from them into the environment.

To study the functional state of the external respiration apparatus, both in clinical practice and in physiological laboratories, determination of lung volumes is widely used.

There are four positions of the chest, which correspond to the four main volumes of the lungs: tidal, inspiratory reserve volume, expiratory reserve volume and residual volume.

Tidal volume is the amount of air that a person inhales and exhales during quiet breathing. Its volume is 300-700 ml. Tidal volume ensures the maintenance of a certain level of partial pressure of oxygen and carbon dioxide in the alveolar air, thereby contributing to the normal tension of gases in the arterial blood. Inspiratory reserve volume is the amount of air that can be introduced into the lungs if a maximum inhalation is taken after a quiet inhalation. The inspiratory reserve volume is 1500-2000 ml. The inspiratory reserve volume determines the ability of the lungs to expand further, which is necessary when the body's need for gas exchange increases.

The expiratory reserve volume is the volume of air that is removed from the lungs if, following a calm inhalation and exhalation, a maximum exhalation is performed. It is 1500-2000 ml. The expiratory reserve volume determines the degree of constant stretching of the lungs.

Residual volume is the volume of air that remains in the lungs after maximal exhalation. The residual volume is 1000-1500 ml of air.

Tidal volume, reserve volumes of inhalation and exhalation make up the so-called vital capacity of the lungs.

The vital capacity of the lungs (an indicator of external respiration) is the deepest breathing that a given person is capable of. It is determined by the amount of air that can be removed from the lungs if, after a maximum inhalation, a maximum exhalation is made.

The vital capacity of the lungs in young men is 3.5-4.8 liters, in women 3-3.5 liters). Indicators of vital capacity of the lungs are variable. They depend on gender, age, height, weight, body position, state of the respiratory muscles, level of excitability of the respiratory center and other factors.

The total lung capacity consists of the vital capacity of the lungs and the residual air volume.

Collapsed air is the minimum amount of air that remains in the lungs after a bilateral open pneumothorax. The presence of collapsed air in the lungs is proven by simple experiment. It has been established that a piece of lung tissue after pneumothorax floats in water, and the lung of a stillborn (not breathing) fetus drowns.

Pulmonary ventilation - the amount of air exchanged in 1 minute. Due to pulmonary ventilation, the alveolar air is renewed and the partial pressure of oxygen and carbon dioxide is maintained in it at a level that ensures normal gas exchange. Pulmonary ventilation is determined by multiplying the tidal volume by the number of breaths in 1 minute (minute respiratory volume). In an adult in a state of relative physiological rest, pulmonary ventilation is 8 liters per minute. Determination of minute volume of respiration has diagnostic value.

Lung volumes can be determined using special devices - a spirometer and a spirograph. The spirographic method allows you to graphically record the values ​​of lung volumes,

Transport of oxygen by blood. Oxygen in the blood is in two states: physical dissolution and in chemical connection with hemoglobin. Of the 19 vol% oxygen extracted from arterial blood, only 0.3 vol% is dissolved in the plasma, while the rest of the oxygen is chemically bound to the hemoglobin of red blood cells.

Hemoglobin forms a very fragile, easily dissociable compound with oxygen - oxyhemoglobin. 1 g of hemoglobin binds 1.34 ml of oxygen. The hemoglobin content in the blood averages 140 g/l (14 g%). 100 ml of blood can bind 14 X 134 = 18.76 ml of oxygen (or 19 vol%), which is basically the so-called oxygen capacity of the blood. Therefore, the oxygen carrying capacity of blood represents the maximum amount of oxygen that can be bound by 100 ml of blood.

The affinity of hemoglobin for oxygen decreases significantly when the blood reaction shifts to the acidic side, which is observed in the tissues and cells of the body due to the formation of carbon dioxide. This property of hemoglobin is important for the body.

Transport of carbon dioxide by blood. The solubility of carbon dioxide in the blood is higher than the solubility of oxygen. However, only 2.5-3 vol% of carbon dioxide out of its total amount (55-58 vol%) is in a dissolved state. Most of the carbon dioxide is contained in the blood and red blood cells in the form of carbonic acid salts (48-51 vol%), about 4-5 vol% - in combination with hemoglobin in the form of carbhemoglobin, about 2/3 of all carbon dioxide compounds are in the plasma and about 1/3 in erythrocytes.

It has now been established that red blood cells contain carbonic anhydrase (carbonic anhydrase), a biological catalyst, an enzyme that significantly (300 times) accelerates the breakdown of carbonic acid in the capillaries of the lungs. In tissue capillaries, with the participation of carbonic anhydrase, carbonic acid is synthesized in erythrocytes. The activity of carbonic anhydrase in erythrocytes is so great that the synthesis of carbonic acid is accelerated tens of thousands of times. Carbonic acid removes bases from reduced hemoglobin, resulting in the formation of carbonic acid salts - sodium bicarbonates in plasma and potassium bicarbonates in red blood cells. In addition, hemoglobin forms a chemical compound with carbon dioxide - carbhemoglobin.

The ultimate goal of respiration is to supply all cells with oxygen and remove carbon dioxide from the body. To achieve this goal of breathing, a number of conditions are necessary: ​​1) normal operation of the external respiratory apparatus and sufficient ventilation of the lungs; 2) normal transport of gases by blood; 3) providing the circulatory system with sufficient blood flow; 4) the ability of tissues to “take” oxygen from flowing blood, utilize it and release carbon dioxide into the blood.

Thus, tissue respiration is ensured by functional relationships between the respiratory, blood and circulatory systems.

The rhythmic sequence of inhalation and exhalation, as well as changes in the nature of respiratory movements depending on the state of the body (rest, work of varying intensity, emotional manifestations, etc.) are regulated by the respiratory center.

The respiratory center, located in the medulla oblongata, sends impulses to the motor neurons of the opium brain, which innervate the respiratory muscles. The diaphragm is innervated by axons of motor neurons located at the level of the III-IV cervical segments of the spinal cord. Motor neurons, processes that form the intercostal nerves that innervate the intercostal muscles, are located in the anterior horns (III-XII) of the thoracic segments of the spinal cord.

Regulation of the activity of the respiratory center is carried out with the help of humoral, reflex mechanisms and nerve impulses coming from the overlying parts of the brain.

A specific regulator of the activity of neurons in the respiratory center is carbon dioxide, which acts on respiratory neurons directly and indirectly. In the neurons of the respiratory center, during their activity, metabolic products (metabolites) are formed, including carbon dioxide, which has a direct effect on inspiratory nerve cells, exciting them. In the reticular formation of the medulla oblongata, near the respiratory center, chemoreceptors sensitive to carbon dioxide were found. With an increase in carbon dioxide tension in the blood, chemoreceptors are excited, and nerve impulses are sent to inspiratory neurons, which leads to an increase in their activity.

In the mechanism of the stimulating effect of carbon dioxide on the respiratory center, an important place belongs to the chemoreceptors of the vascular bed. In the area of ​​the carotid sinuses and aortic arch, chemoreceptors were found that are sensitive to changes in the tension of carbon dioxide and oxygen in the blood.

The experiment showed that washing the carotid sinus or aortic arch, which are humorally isolated but with preserved nerve connections, with a liquid containing a high carbon dioxide content is accompanied by stimulation of respiration (Heymans reflex). In similar experiments, it was found that an increase in oxygen tension in the blood inhibits the activity of the respiratory center.

Regulation of the activity of the respiratory center is represented by three levels.

The first level of regulation is the spinal cord. The centers of the phrenic and intercostal nerves are located here, causing contraction of the respiratory muscles. However, this level of breathing regulation cannot ensure a rhythmic change in the phases of the respiratory cycle, since a huge number of afferent impulses from the respiratory apparatus, bypassing the spinal cord, are sent directly to the medulla oblongata.

The second level of regulation is the medulla oblongata. Here is the respiratory Center, which processes a variety of afferent impulses coming from the respiratory apparatus, as well as from the main reflexogenic vascular zones. This level of regulation ensures a rhythmic change in the phases of breathing and the activity of spinal motor neurons, the axons of which innervate the respiratory muscles.

The third level of regulation is the upper parts of the brain, including cortical neurons. Only with the participation of the cerebral cortex is it possible to adequately adapt the reaction of the respiratory system to changing environmental conditions.

Artificial respiration is usually used in cases of spontaneous breathing or a sharp decrease in pulmonary ventilation.

Effective methods of artificial respiration have become widespread - mouth to mouth and mouth to nose, based on the blowing of exhaled air into the lungs of the victim by the first aid provider. With this method of artificial respiration, the required level of pulmonary ventilation can be ensured.

Artificial respiration mouth to mouth and mouth to nose is carried out in the following order. The victim is placed on a horizontal surface (floor, table, hard bed) without a pillow, with his head thrown back as far as possible. A cushion or pillow 10-15 cm high is placed under the shoulders. The lower jaw is pushed forward. Before starting artificial respiration, make sure that the airways are open and, if necessary, free the oral cavity from foreign bodies and vomit. Then the exhaled air is blown into the victim’s mouth or nose. The oxygen content in the exhaled air (16-17%) is quite sufficient to ensure normal gas exchange, and a high percentage of carbon dioxide (3-4%) helps stimulate the victim’s respiratory center.

Mouth-to-mouth breathing can be done using an oronasal mask from an anesthesia machine or a special air duct. In addition, air can be rhythmically forced into the donkey's respiratory tract by bellows or by a pump driven manually or by a motor.

Methods of artificial respiration based on chest compression (exhalation) and passive expansion (inhalation) are currently practically not used, since they do not provide a sufficient level of pulmonary ventilation.

In recent years, long-term artificial respiration has been carried out using special devices of various designs with automatic regulation of the depth and frequency of respiratory movements depending on the oxygen content in the blood.

Features of breathing regulation in childhood.

By the time a child is born, his respiratory center is able to provide a rhythmic change in the phases of the respiratory cycle (inhalation and exhalation), but not as perfectly as in older children. This is due to the fact that at the time of birth the functional formation of the respiratory center has not yet completed.

This is evidenced by the great variability in the frequency, depth, and rhythm of breathing in young children. The excitability of the respiratory center during this period is low.

By the age of 11, the ability to adapt breathing to various living conditions already becomes well expressed.

The sensitivity of the respiratory center to carbon dioxide increases with age and at school age reaches approximately the level of adults.

It should be noted that during puberty, temporary disturbances in the regulation of breathing occur, and the body of adolescents is less resistant to oxygen deficiency than the body of an adult.

As the cerebral cortex matures, the ability to voluntarily change breathing improves - to suppress respiratory movements or produce maximum ventilation of the lungs.

Voluntary changes in breathing play an important role when performing a number of breathing exercises and help to correctly combine certain movements with the breathing phase.

One of the conditions for proper breathing is taking care of the development of the chest. Correct body positions for children during various activities promote expansion of the chest and facilitate deep breathing. On the contrary, when the torso is bent, the normal activity of the lungs is disrupted, or less air is absorbed, and at the same time oxygen.

Much attention is paid in the process of physical education to the education of children and adolescents in proper breathing through the nose in a state of relative rest, during work activity and performing physical exercises. Breathing exercises, swimming, rowing, and skiing especially help improve breathing.

Breathing exercises also have great health benefits. It is recommended to perform breathing exercises up to 3 times a day, at least an hour after meals.

Air purity and its physical and chemical properties are of great importance for the health and performance of children and adolescents. Staying children and adolescents in a dusty, poorly ventilated room causes not only a deterioration in the functional state of the body, but also many diseases.

The human body is not indifferent to the content of positive and negative ions in the air. Light and negative ions have a beneficial effect on humans, this was the basis for the use of artificial ionization of the air in enclosed spaces of children's institutions and gyms.

The physiological need of children for clean air is provided by the installation of a central exhaust ventilation system and vents or transoms.

Control questions

1. The essence and meaning of breathing.

2. Links of the respiratory process.

3. Phases of the respiratory cycle and their characteristics.

4. Types of pulmonary volumes.

5. Pulmonary ventilation.

6. The mechanism of the first breath of a newborn.

7. Methods of artificial respiration. SRS:

Types of hypoxia. Pathological types of breathing. Breathing during physical activity.

Regulation of breathing and its age-related features

Respiratory center. Regulation of breathing is carried out by the central nervous system, special areas of which determine automatic breathing - alternating inhalation and exhalation and arbitrary breathing, providing adaptive changes in the respiratory system corresponding to a specific external situation and activity. The group of nerve cells responsible for the respiratory cycle is usually called respiratory center. The respiratory center is located in the medulla oblongata, its destruction leads to respiratory arrest. The respiratory center is in a state of constant activity: excitation impulses arise rhythmically in it. These impulses arise automatically. Even after the centripetal pathways leading to the respiratory center are completely turned off, rhythmic activity can be registered in it. The automaticity of the respiratory center is associated with the metabolic process in it. Rhythmic impulses are transmitted from the respiratory center through centrifugal neurons to the intercostal muscles and diaphragm, ensuring a sequential alternation of inhalation and exhalation. The activity of the respiratory center is regulated reflexively, by impulses coming from various receptors, and humorally, changing depending on the chemical composition of the blood. Reflex regulation. Receptors, the excitation of which enters the respiratory center along centripetal pathways, include chemoreceptors, located in large vessels (arteries) and responding to a decrease in oxygen tension in the blood and an increase in the concentration of carbon dioxide, and mechanoreceptors lungs and respiratory muscles. The regulation of breathing is also influenced by receptors in the airways. The receptors of the lungs and respiratory muscles are of particular importance in the alternation of inhalation and exhalation; the ratio of these phases of the respiratory cycle, their depth and frequency, largely depends on them. When you inhale, when the lungs stretch, the receptors in their walls are irritated. Impulses from the lung receptors along the centripetal fibers of the vagus nerve reach the respiratory center, inhibit the inhalation center and excite the exhalation center. As a result, the respiratory muscles relax, the chest drops, the diaphragm takes the form of a dome, the volume of the chest decreases and exhalation occurs. Exhalation, in turn, reflexively stimulates inhalation. The cerebral cortex takes part in the regulation of breathing, providing the finest adaptation of breathing to the needs of the body in connection with changes in environmental conditions and the vital functions of the body. A person can arbitrarily, at will, hold his breath for a while, change the rhythm and depth of breathing movements. The influences of the cerebral cortex explain the pre-start changes in breathing in athletes - a significant deepening and increased breathing before the start of the competition. It is possible to develop conditioned breathing reflexes. If you add 5-7% carbon dioxide to the inhaled air, which in such a concentration speeds up breathing, and accompany the inhalation with the sound of a metronome or a bell, then after several combinations the bell or sound of a metronome alone will cause increased breathing. Humoral influences on the respiratory center. The chemical composition of the blood, in particular its gas composition, has a great influence on the state of the respiratory center. The accumulation of carbon dioxide in the blood irritates the receptors in the blood vessels carrying blood to the head and reflexively stimulates the respiratory center. Other acidic products entering the blood act in a similar way, for example lactic acid, the content of which in the blood increases during muscle work. Features of breathing regulation in childhood. By the time a child is born, his respiratory center is able to ensure a rhythmic change in the phases of the respiratory cycle (inhalation and exhalation), but not as perfectly as in older children. This is due to the fact that at the time of birth the functional formation of the respiratory center has not yet completed. This is evidenced by the great variability in the frequency, depth, and rhythm of breathing in young children. The excitability of the respiratory center in newborns and infants is low. Children in the first years of life are more resistant to oxygen deficiency (hypoxia) than older children. The formation of the functional activity of the respiratory center occurs with age. By the age of 11, the ability to adapt breathing to various living conditions is already well expressed. The sensitivity of the respiratory center to carbon dioxide increases with age and at school age reaches approximately the level of adults. It should be noted that during puberty, temporary disturbances in the regulation of breathing occur and the body of adolescents is less resistant to oxygen deficiency than the body of an adult. The need for oxygen, which increases as the body grows and develops, is ensured by improving the regulation of the respiratory apparatus, leading to an increasing economization of its activity. As the cerebral cortex matures, the ability to voluntarily change breathing improves - to suppress respiratory movements or produce maximum ventilation of the lungs. In an adult, during muscular work, pulmonary ventilation increases due to increased and deepening breathing. Activities such as running, swimming, skating, skiing, and cycling dramatically increase the volume of pulmonary ventilation. In trained people, pulmonary gas exchange increases mainly due to an increase in the depth of breathing. Children, due to the characteristics of their breathing apparatus, cannot significantly change the depth of breathing during physical exertion, but rather increase their breathing speed. The already frequent and shallow breathing in children during physical activity becomes even more frequent and shallow. This results in lower ventilation efficiency, especially in young children. The body of a teenager, unlike an adult, quickly reaches the maximum level of oxygen consumption, but also stops working faster due to the inability to maintain oxygen consumption at a high level for a long time. Voluntary changes in breathing play an important role when performing a number of breathing exercises and help to correctly combine certain movements with the breathing phase (inhalation and exhalation). One of the important factors in ensuring optimal functioning of the respiratory system under various types of loads is the regulation of the ratio of inhalation and exhalation. The most effective and facilitating physical and mental activity is the respiratory cycle, in which the exhalation is longer than the inhalation. Teaching children to breathe correctly when walking, running and other activities is one of the teacher’s tasks. One of the conditions for proper breathing is taking care of the development of the chest. For this, correct body position is important, especially while sitting at a desk, breathing exercises and other physical exercises that develop the muscles that move the chest. Particularly useful in this regard are sports such as swimming, rowing, skating, and skiing. Usually a person With a well-developed chest breathes evenly and correctly. It is necessary to teach children to walk and stand with a straight posture, as this helps expand the chest, facilitates the functioning of the lungs and ensures deeper breathing. When the body is bent, less air enters the body. The correct position of the body of children during various activities helps to expand the chest and facilitates deep breathing. On the contrary, when the body is bent, the opposite conditions are created, the normal activity of the lungs is disrupted, they absorb less air, and at the same time oxygen. Much attention is paid in the process of physical education to the education of children and adolescents in proper breathing through the nose in a state of relative rest, during work activity and performing physical exercises. Breathing exercises, swimming, rowing, skating, and skiing especially help improve breathing. Breathing exercises also have great health benefits. When you inhale calmly and deeply, intrathoracic pressure decreases as the diaphragm moves down. The flow of venous blood to the right atrium increases, which facilitates the work of the heart. The diaphragm, which descends during inhalation, massages the liver and upper abdominal organs, helps remove metabolic products from them, and from the liver - venous stagnant blood and bile. During deep exhalation, the diaphragm rises, which increases the outflow of venous blood from the lower extremities, pelvis and abdomen. As a result, blood circulation is facilitated. At the same time, with a deep exhalation, a light massage of the heart occurs and its blood supply improves. In breathing exercises there are three main types of breathing, called according to the form of execution - chest, abdominal and full breathing. Considered to be the most beneficial for health full breath. There are various breathing exercises. It is recommended to perform these complexes up to 3 times a day, at least an hour after meals. Hygienic importance of indoor air. Air purity and its physical and chemical properties are of great importance for the health and performance of children and adolescents. Staying children and adolescents in a dusty, poorly ventilated room causes not only a deterioration in the functional state of the body, but also many diseases. It is known that in closed, poorly ventilated and aerated rooms, simultaneously with an increase in air temperature, its physicochemical properties sharply deteriorate. It is worth noting that the human body is not indifferent to the content of positive and negative ions in the air. In atmospheric air, the number of positive and negative ions is almost equal; light ions significantly predominate over heavy ones. Studies have shown that light and negative ions have a beneficial effect on humans, and their number in work areas is gradually decreasing. Positive and heavy ions begin to predominate, which depress human life. In schools, before classes, 1 cm 3 of air contains about 467 light and 10 thousand heavy ions, and at the end of the school day the number of the former decreases to 220, and the latter increases to 24 thousand. The beneficial physiological effect of negative air ions was the basis for the use of artificial ionization of air closed premises of children's institutions, gyms. Sessions of short (10 minutes) stay in a room where 1 cm 3 of air contains 450-500 thousand light ions produced by a special air ionizer not only have a positive effect on performance, but also have a hardening effect. In parallel with the deterioration of the ionic composition, the increase in temperature and air humidity in classrooms, the concentration of carbon dioxide increases, ammonia and various organic substances accumulate. The deterioration of the physico-chemical properties of air, especially in rooms with a reduced height, entails a significant deterioration in the performance of cells in the human cerebral cortex. From the beginning to the end of classes, the dustiness of the air and its bacterial contamination increases, especially if wet cleaning and ventilation of the premises were poorly carried out before the start of classes. The number of colonies of microorganisms in 1 m 3 of air in such conditions by the end of classes in the second shift increases 6-7 times, along with harmless microflora it also contains pathogenic ones. With a room height of 3.5 m, at least 1.43 m 2 per student is required. Reducing the height of educational and residential (boarding school) premises requires an increase in area per student. With a room height of 3 m, a minimum of 1.7 m 2 is required per student, and with a height of 2.5 m - 2.2 m 2. Since during physical work (physical education lessons, work in workshops) the amount of carbon dioxide released by students increases 2-3 times, the required volume of air that needs to be provided in the gym and workshops accordingly increases to 10-15 m 3. Accordingly, the area per student increases. The physiological need of children for clean air is provided by the installation of a central exhaust ventilation system and vents or frames. The flow of air into the room and its change occur naturally. Air exchange occurs through the pores of the building material, cracks in window frames, and doors due to the difference in temperature and pressure inside and outside the room. However, this exchange is limited and insufficient. The device of supply and exhaust artificial ventilation in children's institutions has not justified itself. For this reason, a central exhaust ventilation device with wide aeration - an influx of atmospheric air - has become widespread. The opening part of the windows (transoms, vents) in each room in its total area should be at least 1:50 (preferably 1:30) of the floor area. Transoms are more suitable for ventilation, since their area is larger and outside air flows upward through them, which ensures effective air exchange in the room. Through ventilation is 5-10 times more effective than usual. With through ventilation, the content of microorganisms in indoor air also sharply decreases. The current norms and rules provide for natural exhaust ventilation in the amount of a single exchange per hour. It is assumed that the remaining volume of air is removed through recreational premises, followed by exhaust from sanitary facilities and through fume hoods in chemistry laboratories. In workshops, the air flow should provide 20 m 3 / h, in gyms - 80 m 3 / h per student. Additional fume hoods are installed in chemical and physical laboratories and in the carpentry workshop. In order to combat dust, general cleaning should be carried out at least once a month, including washing panels, radiators, window sills, doors, and thoroughly wiping furniture. Microclimate. Temperature, humidity and air velocity (cooling force) in a classroom characterize its microclimate. The importance of an optimal microclimate for the health and performance of students and teachers is no less than other parameters of the sanitary condition and maintenance of educational premises of schools and vocational schools. Due to the increase in outdoor and indoor air temperatures, schoolchildren have noticed a decrease in performance. In different seasons of the year, children and adolescents show peculiar changes in attention and memory. The relationship between fluctuations in outside air temperature and the performance of children partly served as the basis for establishing the start and end dates of the school year. The best time for studying is considered to be autumn and winter. During school hours, even with negative outside temperatures, the temperature in the classrooms already increases by 4° before the big break, and by the end of classes - by 5.5°. Fluctuations in temperature naturally affect the thermal state of students, which is reflected in changes in the temperature of the skin of the extremities (feet and hands). The temperature of these parts of the body increases with increasing air temperature. High temperatures in classrooms (up to 26°) lead to stress on thermoregulatory processes and decreased performance. In such conditions, the mental performance of students by the end of lessons decreases sharply. The influence of temperature conditions on the performance of students during physical education and labor is even more clearly evident. In the premises of schools, boarding schools, boarding schools at schools, vocational schools with a relative humidity of 40-60% and an air speed of no more than 0.2 m/s, its temperature is normalized in accordance with climatic regions (Table 19). the air temperature in the room both vertically and horizontally is set within 2-3°C. The low air temperature in the gym, workshops and recreational premises corresponds to the type of activity of children and adolescents in these premises.

Respiratory center. Regulation of breathing is carried out by the central nervous system, special areas of which determine automatic breathing - alternating inhalation and exhalation and arbitrary breathing, providing adaptive changes in the respiratory system corresponding to a specific external situation and activity. The group of nerve cells responsible for the respiratory cycle is called respiratory center. The respiratory center is located in the medulla oblongata, its destruction leads to respiratory arrest.
The respiratory center is in a state of constant activity: excitation impulses arise rhythmically in it. These impulses arise automatically. Even after the centripetal pathways leading to the respiratory center are completely turned off, rhythmic activity can be registered in it. The automaticity of the respiratory center is associated with the metabolic process in it. Rhythmic impulses are transmitted from the respiratory center through centrifugal neurons to the intercostal muscles and diaphragm, ensuring a sequential alternation of inhalation and exhalation.
The activity of the respiratory center is regulated reflexively, by impulses coming from various receptors, and humorally, changing depending on the chemical composition of the blood.
Reflex regulation. Receptors, the excitation of which enters the respiratory center along centripetal pathways, include chemoreceptors, located in large vessels (arteries) and responding to a decrease in oxygen tension in the blood and an increase in the concentration of carbon dioxide, and mechanoreceptors lungs and respiratory muscles. The regulation of breathing is also influenced by receptors in the airways. The receptors of the lungs and respiratory muscles are of particular importance in the alternation of inhalation and exhalation; the ratio of these phases of the respiratory cycle, their depth and frequency, largely depends on them.
When you inhale, when the lungs stretch, the receptors in their walls are irritated. Impulses from the lung receptors along the centripetal fibers of the vagus nerve reach the respiratory center, inhibit the inhalation center and excite the exhalation center. As a result, the respiratory muscles relax, the chest drops, the diaphragm takes the form of a dome, the volume of the chest decreases and exhalation occurs. Exhalation, in turn, reflexively stimulates inhalation.
The cerebral cortex takes part in the regulation of breathing, providing the finest adaptation of breathing to the needs of the body in connection with changes in environmental conditions and the vital functions of the body. A person can arbitrarily, at will, hold his breath for a while, change the rhythm and depth of breathing movements. The influences of the cerebral cortex explain the pre-start changes in breathing in athletes - a significant deepening and increased breathing before the start of the competition. It is possible to develop conditioned breathing reflexes. If you add 5-7% carbon dioxide to the inhaled air, which in such a concentration speeds up breathing, and accompany the inhalation with the sound of a metronome or a bell, then after several combinations the bell or sound of a metronome alone will cause increased breathing.
Humoral influences on the respiratory center. The chemical composition of the blood, in particular its gas composition, has a great influence on the state of the respiratory center. The accumulation of carbon dioxide in the blood irritates the receptors in the blood vessels carrying blood to the head and reflexively stimulates the respiratory center. Other acidic products entering the blood act in a similar way, for example lactic acid, the content of which in the blood increases during muscle work.
Features of breathing regulation in childhood. By the time a child is born, his respiratory center is able to ensure a rhythmic change in the phases of the respiratory cycle (inhalation and exhalation), but not as perfectly as in older children. This is due to the fact that at the time of birth the functional formation of the respiratory center has not yet completed. This is evidenced by the great variability in the frequency, depth, and rhythm of breathing in young children. The excitability of the respiratory center in newborns and infants is low. Children in the first years of life are more resistant to oxygen deficiency (hypoxia) than older children.
The formation of the functional activity of the respiratory center occurs with age. By the age of 11, the ability to adapt breathing to various living conditions is already well expressed.
The sensitivity of the respiratory center to carbon dioxide increases with age and at school age reaches approximately the level of adults. It should be noted that during puberty, temporary disturbances in the regulation of breathing occur and the body of adolescents is less resistant to oxygen deficiency than the body of an adult. The need for oxygen, which increases as the body grows and develops, is ensured by improved regulation of the respiratory apparatus, leading to an increasing economization of its activity. As the cerebral cortex matures, the ability to voluntarily change breathing improves - to suppress respiratory movements or produce maximum ventilation of the lungs.
In an adult, during muscular work, pulmonary ventilation increases due to increased and deepening breathing. Activities such as running, swimming, skating, skiing, and cycling dramatically increase the volume of pulmonary ventilation. In trained people, pulmonary gas exchange increases mainly due to an increase in the depth of breathing. Children, due to the characteristics of their breathing apparatus, cannot significantly change the depth of breathing during physical exertion, but rather increase their breathing speed. The already frequent and shallow breathing in children during physical activity becomes even more frequent and shallow. This results in lower ventilation efficiency, especially in young children.
The body of a teenager, unlike an adult, quickly reaches the maximum level of oxygen consumption, but also stops working faster due to the inability to maintain oxygen consumption at a high level for a long time.
Voluntary changes in breathing play an important role when performing a number of breathing exercises and help to correctly combine certain movements with the breathing phase (inhalation and exhalation).
One of the important factors in ensuring optimal functioning of the respiratory system under various types of loads is the regulation of the ratio of inhalation and exhalation. The most effective and facilitating physical and mental activity is the respiratory cycle, in which the exhalation is longer than the inhalation.
Teaching children to breathe correctly when walking, running and other activities is one of the teacher’s tasks. One of the conditions for proper breathing is taking care of the development of the chest. For this, correct body position is important, especially while sitting at a desk, breathing exercises and other physical exercises that develop the muscles that move the chest. Particularly useful in this regard are sports such as swimming, rowing, skating, and skiing.
Usually a person With a well-developed chest breathes evenly and correctly. It is necessary to teach children to walk and stand with a straight posture, as this helps expand the chest, facilitates the functioning of the lungs and ensures deeper breathing. When the body is bent, less air enters the body.
The correct position of the body of children during various activities helps to expand the chest and facilitates deep breathing. On the contrary, when the body is bent, the opposite conditions are created, the normal activity of the lungs is disrupted, they absorb less air, and at the same time oxygen.
Much attention is paid in the process of physical education to the education of children and adolescents in proper breathing through the nose in a state of relative rest, during work activity and performing physical exercises. Breathing exercises, swimming, rowing, skating, and skiing especially help improve breathing.
Breathing exercises also have great health benefits. When you inhale calmly and deeply, intrathoracic pressure decreases as the diaphragm moves down. The flow of venous blood to the right atrium increases, which facilitates the work of the heart. The diaphragm, which descends during inhalation, massages the liver and upper abdominal organs, helps remove metabolic products from them, and from the liver - venous stagnant blood and bile.
During deep exhalation, the diaphragm rises, which increases the outflow of venous blood from the lower extremities, pelvis and abdomen. As a result, blood circulation is facilitated. At the same time, with a deep exhalation, a light massage of the heart occurs and its blood supply improves.
In breathing exercises there are three main types of breathing, called according to the form of execution - chest, abdominal and full breathing. Considered to be the most beneficial for health full breath. There are various breathing exercises. It is recommended to perform these complexes up to 3 times a day, at least an hour after meals.
Hygienic importance of indoor air. Air purity and its physical and chemical properties are of great importance for the health and performance of children and adolescents. Staying children and adolescents in a dusty, poorly ventilated room causes not only a deterioration in the functional state of the body, but also many diseases.
It is known that in closed, poorly ventilated and aerated rooms, simultaneously with an increase in air temperature, its physicochemical properties sharply deteriorate. The human body is not indifferent to the content of positive and negative ions in the air. In atmospheric air, the number of positive and negative ions is almost equal; light ions significantly predominate over heavy ones.
Studies have shown that light and negative ions have a beneficial effect on humans, and their number in work areas is gradually decreasing. Positive and heavy ions begin to predominate, which depress human life. In schools, before classes, 1 cm 3 of air contains about 467 light and 10 thousand heavy ions, and at the end of the school day the number of the former decreases to 220, and the latter increases to 24 thousand.
The beneficial physiological effect of negative air ions was the basis for the use of artificial ionization of indoor air in children's institutions and gyms. Sessions of short (10 minutes) stay in a room where 1 cm 3 of air contains 450-500 thousand light ions produced by a special air ionizer not only have a positive effect on performance, but also have a hardening effect.
In parallel with the deterioration of the ionic composition, the increase in temperature and air humidity in classrooms, the concentration of carbon dioxide increases, ammonia and various organic substances accumulate. The deterioration of the physico-chemical properties of air, especially in rooms with a reduced height, entails a significant deterioration in the performance of cells in the human cerebral cortex.
From the beginning to the end of classes, the dustiness of the air and its bacterial contamination increases, especially if wet cleaning and ventilation of the premises were poorly carried out before the start of classes. The number of colonies of microorganisms in 1 m 3 of air in such conditions by the end of classes in the second shift increases 6-7 times, along with harmless microflora it also contains pathogenic ones.
With a room height of 3.5 m, at least 1.43 m 2 per student is required. Reducing the height of educational and residential (boarding school) premises requires an increase in area per student. With a room height of 3 m, a minimum of 1.7 m 2 is required per student, and with a height of 2.5 m - 2.2 m 2.
Since during physical work (physical education lessons, work in workshops) the amount of carbon dioxide released by students increases 2-3 times, the required volume of air that needs to be provided in the gym and workshops accordingly increases to 10-15 m 3. Accordingly, the area per student increases.
The physiological need of children for clean air is provided by the installation of a central exhaust ventilation system and vents or transoms.
The flow of air into the room and its change occur naturally. Air exchange occurs through the pores of the building material, cracks in window frames, and doors due to the difference in temperature and pressure inside and outside the room. However, this exchange is limited and insufficient.
The device of supply and exhaust artificial ventilation in children's institutions has not justified itself. Therefore, the device of central exhaust ventilation with wide aeration - an influx of atmospheric air - has become widespread.
The opening part of the windows (transoms, vents) in each room in its total area should be at least 1:50 (preferably 1:30) of the floor area. Transoms are more suitable for ventilation, since their area is larger and outside air flows upward through them, which ensures effective air exchange in the room. Through ventilation is 5-10 times more effective than usual. With through ventilation, the content of microorganisms in indoor air also sharply decreases.
The current norms and rules provide for natural exhaust ventilation in the amount of a single exchange per hour. It is assumed that the remaining volume of air is removed through recreational premises, followed by exhaust from sanitary facilities and through fume hoods in chemistry laboratories. In workshops, the air flow should provide 20 m 3 / h, in gyms - 80 m 3 / h per student. Additional fume hoods are installed in chemical and physical laboratories and in the carpentry workshop. In order to combat dust, general cleaning should be carried out at least once a month, including washing panels, radiators, window sills, doors, and thoroughly wiping furniture.
Microclimate. Temperature, humidity and air velocity (cooling force) in a classroom characterize its microclimate. The importance of an optimal microclimate for the health and performance of students and teachers is no less than other parameters of the sanitary condition and maintenance of educational premises of schools and vocational schools. Due to the increase in outdoor and indoor air temperatures, schoolchildren have noticed a decrease in performance. In different seasons of the year, children and adolescents show peculiar changes in attention and memory. The relationship between fluctuations in outside air temperature and the performance of children partly served as the basis for establishing the start and end dates of the school year. The best time for studying is considered to be autumn and winter.
During school hours, even with negative outside temperatures, the temperature in the classrooms already increases by 4° before the big break, and by the end of classes - by 5.5°. Fluctuations in temperature naturally affect the thermal state of students, which is reflected in changes in the temperature of the skin of the extremities (feet and hands). The temperature of these parts of the body increases with increasing air temperature.
High temperatures in classrooms (up to 26°) lead to stress on thermoregulatory processes and decreased performance. In such conditions, the mental performance of students by the end of lessons decreases sharply. The influence of temperature conditions on the performance of students during physical education and labor is even more clearly evident.
In the premises of schools, boarding schools, boarding schools at schools, vocational schools with a relative humidity of 40-60% and an air speed of no more than 0.2 m/s, its temperature is normalized in accordance with climatic regions (Table 19). the air temperature in the room both vertically and horizontally is set within 2-3°C. The low air temperature in the gym, workshops and recreational premises corresponds to the type of activity of children and adolescents in these premises.

During classes, special care should be taken about the thermal comfort of students sitting in the first row from the windows, strictly observe the established gaps, and do not seat children near radiators (stoves). In schools with strip glazing, the gaps between the first row of desks and the windows in winter should be increased to 1.0-1.2 m. Due to the low thermal resistance of glass and the high air permeability of window frames, the large glazed surface of the outer wall in winter becomes a source of powerful radiation and convection cooling. Already at an outside air temperature below -15°C, the temperature of the inner surface of the glass drops to an average of 6-10°C, and under the influence of wind to 0°C. Hygienic requirements for heating schools. Of the existing central heating systems in children's institutions, a low-pressure water heating system is used. This heating, when using devices with large heat capacity, ensures uniform air temperature in the room throughout the day, does not make the air too dry and eliminates the sublimation of dust on heating devices. Dutch ovens, which have a high heat capacity, are used as local heating appliances. The furnaces are fired from the corridors at night, and the pipes are closed no later than 2 hours before the students arrive.

Chapter XII Age-related characteristics of excretory organs.
Personal hygiene. Hygiene of clothes and shoes

§1. Structure and function of the kidneys
§2. Structure and function of the skin
§3. Hygienic requirements for children's clothing and shoes
§4. Frostbite, burns. Prevention and first aid

The importance of excretory organs. The excretory organs play an important role in maintaining the constancy of the internal environment; they remove metabolic products from the body that cannot be used, excess water and salts. The excretion processes involve the lungs, intestines, skin and kidneys. The lungs remove carbon dioxide, water vapor, and volatile substances from the body. Heavy metal salts and excess unabsorbed nutrients are removed from the intestines with feces. The sweat glands of the skin secrete water, salts, and organic substances; their increased activity is observed during intense muscular work and an increase in ambient temperature.
The main role in excretory processes belongs to the kidneys, which remove water, salts, ammonia, urea, and uric acid from the body, restoring the constancy of the osmotic properties of the blood. Some toxic substances produced in the body or taken in the form of drugs are eliminated through the kidneys.
The kidneys maintain a certain constant blood reaction. When acidic or alkaline metabolic products accumulate in the blood, the release of excess corresponding salts through the kidneys increases. In maintaining a constant blood reaction, the ability of the kidneys to synthesize ammonia, which binds acidic products, plays a very important role.

Structure and function of the kidneys

The structure of the kidneys. The kidneys (there are two of them - right and left) are bean-shaped; The outer edge of the kidney is convex, the inner edge is concave. They are red-brown in color, weighing about 120 g.
There is a deep notch on the concave, inner edge of the kidney. This is the gate of the kidney. The renal artery enters here, and the renal vein and ureter exit.

The kidneys receive more blood than any other organ, and they produce urine from substances carried by the blood. The structural and functional unit of the kidney is the renal corpuscle - nephron(Fig. 43), each kidney has about 1 million nephrons. The nephron consists of two main parts: blood vessels and the renal tubule.
The total length of the tubules of one kidney corpuscle reaches 35-50 mm. The kidneys have approximately 130 km of tubes through which fluid passes. Every day, the kidneys filter about 170 liters of fluid, which is concentrated in about 1.5 liters of urine and removed from the body.
Age-related features of kidney function. WITH The amount and composition of urine changes with age. Children produce relatively more urine than adults, and urination occurs more often due to intense water metabolism and a relatively large amount of water and carbohydrates in the child’s diet.
Only in the first 3-4 days the amount of urine released in children is small. A one-month-old child produces 350-380 ml of urine per day, by the end of the first year of life - 750 ml, at 4-5 years - about 1 liter, at 10 years - 1.5 liters, and during puberty - up to 2 liters.
In newborns, the urine reaction is strongly acidic; with age, it becomes slightly acidic. The reaction of urine may vary depending on the nature of the food the child receives. When eating predominantly meat foods, the body produces a lot of acidic metabolic products, and accordingly, the urine becomes more acidic. When eating plant foods, the urine reaction shifts to the alkaline side.
In newborns, the permeability of the renal epithelium is increased, which is why protein is almost always found in the urine. Healthy children and adults should not have protein in their urine.
Urination and its mechanism. Emission of urine is a reflex process. Urine entering the bladder causes an increase in pressure in it, which irritates the receptors located in the bladder wall. There is excitement that reaches the micturition center in the lower part of the spinal cord. From here, impulses travel to the muscles of the bladder, causing it to contract; the sphincter relaxes and urine flows from the bladder into the urethra. This is the involuntary release of urine. It occurs in infants.
Older children, like adults, can voluntarily hold and force urination. This is due to the establishment of cortical conditioned reflex regulation of urination. "but by the age of two, children have formed conditioned reflex mechanisms of urinary retention not only during the day, but also at night. However, at the age of 5-10 years, children, sometimes before puberty, experience nocturnal involuntary urinary incontinence - enuresis. In the autumn-winter periods of the year, due to the greater possibility of cooling the body, enuresis becomes more frequent. With age, enuresis, associated primarily with functional abnormalities in the psychoneurological status of children, goes away. However, children must be examined by doctors - a urologist and a neurologist.
Enuresis is promoted by mental trauma, overwork (especially from physical exertion), hypothermia, sleep disturbance, irritating, spicy food and an abundance of liquid taken before bedtime. Children experience their illness very hard, experience fear, do not fall asleep for a long time, and then fall into deep sleep, during which a weak urge to urinate is not perceived.
Prevention of diseases of the excretory organs. In orphanages, boarding schools and pioneer camps, children suffering from enuresis require special attention from adults. What happens to a child at night should never be discussed in groups.
Children suffering from enuresis must, as directed by the doctor, establish and strictly observe a daily routine, rest, a properly balanced diet, without irritating, salty and spicy foods, limit fluid intake, especially before bedtime, and exclude heavy physical activity in the afternoon (playing games). football, basketball, volleyball, etc.). Children should be raised at least twice during the night to empty their bladder.
Violation of the rules of personal hygiene can lead to inflammation in children of the urethra and urinary tract, which are highly vulnerable, characterized by reduced resistance and increased desquamation of the epithelium. It is necessary to teach children to keep their external genitalia clean, wash them with warm water and soap in the morning and evening before bed. For these purposes, you need to have a special individual towel, wash it and be sure to boil it once a week.
Prevention of acute and chronic kidney diseases is, first of all, the prevention of infectious diseases (scarlet fever, otitis media, purulent skin lesions, diphtheria, measles, etc.) and their complications.

Structure and function of the skin

Peculiarities of skin structure. The skin covering the human body makes up 5% of body weight, its area in an adult is 1.5-2 m 5. The skin consists of epithelial and connective tissues containing tactile bodies, nerve fibers, blood vessels, sweat and sebaceous glands (Fig. 44).

The skin performs a variety of functions. It participates in maintaining the constancy of the internal environment as an excretory organ. The tactile bodies contained in it are receptors of the skin analyzer and play an important role in ensuring contacts of the body with the external environment. The skin performs an important protective function. It protects the body from mechanical influences, which is achieved by the strength of the superficial stratum corneum, the strength and extensibility of the tissue that forms the skin. Constant renewal of the surface layer of the skin helps cleanse the surface of the body. The role of the skin in the processes of thermoregulation is great: 80% of heat transfer occurs through the skin, which occurs due to the evaporation of sweat and heat radiation. The skin contains thermoreceptors that reflexively maintain body temperature.
Under normal conditions, at a temperature of +18...+-20°C, 1.5% oxygen enters the body through the skin. However, with intense physical work, the supply of oxygen through the skin can increase 4-5 times.
The excretory function of the skin is carried out by the sweat glands. Sweat glands are located in the subcutaneous connective tissue. The number of sweat glands ranges from 2 to 3.5 million. It is individual and determines whether the body sweats more or less. Sweat glands on the body are distributed unevenly, most of them are in the armpits, on the palms of the hands and soles of the feet, and less on the back, legs and thighs. With sweat, a significant amount of water and salts, as well as urea, are released from the body. The daily amount of sweat in an adult at rest is 400-600 ml. About 40 g of table salt and 10 g of nitrogen are released per day through sweat. Carrying out an excretory function, sweat glands help maintain a constant osmotic pressure and blood pH.
Age-related features of the structure and function of the skin. One of the main features of the skin of children and adolescents is that their surface is relatively larger than that of adults. The younger the child, the more skin surface he has per 1 kg of body weight. The absolute surface of the skin in children is smaller than in adults and increases with age. Per 1 kg of body weight there is the following skin surface area: in a newborn - 704 cm2, in a 1-year-old child - 528, in a 6-year-old preschooler - 456, in a 10-year-old schoolchild - 423, in a 15-year-old teenager - 378 and in adults - 221 cm 2.
This feature causes a significantly greater heat transfer from the body of children compared to adults. Moreover, the younger the children, the more pronounced this feature is. High heat transfer also causes high heat generation, which is also higher per unit body weight in children and adolescents than in adults. Over a long period of development, thermoregulatory processes change. Adult-type skin temperature regulation is established by the age of 9 years.
Throughout life, the total number of sweat glands does not change; their size and secretory function increase. The constant number of sweat glands with age determines their greater density in childhood. The number of sweat glands per unit of body surface in children is 10 times greater than in adults. The morphological development of sweat glands is mainly completed by the age of 7 years.
Sweating begins in the 4th week of life. A particularly noticeable increase in the number of functioning sweat glands was noted in the first 2 years. The intensity of sweating on the palms reaches a maximum at 5-7 years of age, then gradually decreases. Heat transfer through evaporation increases during the first year from 260 kcal per 1 m 2 of surface to 570 kcal per 1 m 2.
The secretory activity of the sebaceous glands also changes with age. The activity of these glands reaches a high level in the period immediately preceding the birth of a child. They create a kind of “lubricant” that facilitates the passage of the child through the birth canal. After birth, the secretion of the sebaceous glands fades, its intensification occurs again during puberty and is associated with neuroendocrine changes.
Skin, nails and hair care. Intact skin delays the penetration of most chemicals and microorganisms into the body. Keeping the body clean ensures the normal functioning of all skin functions. On the skin, dirt is retained by excess sebum and sloughing epithelium. The resulting lumps close the skin pores. Blockage of skin pores with dirt prevents the normal separation of the contents of the sweat and sebaceous glands. Pustules form more easily in clogged glands on dirty skin. Pollution causes itching of the skin, scratching, which also contributes to the violation of the integrity of the skin and the penetration of infection. In addition, the bactericidal properties of dirty skin drop sharply; they are almost 17 times lower than clean skin. Due to the release of special substances (lysozyme, etc.), the mucous membranes of the mouth, respiratory tract, gastrointestinal tract and urinary tract also have bactericidal properties.
Many infectious diseases are transmitted through unwashed, dirty hands and infection with worms occurs. Washing with plain and cold water without soap does not dissolve the secretions of the sebaceous glands, and therefore is not enough to keep the skin clean. Soap softens the skin and facilitates the removal of dead epithelial cells. Soap should form a large amount of foam when lathering and not dry out the skin. Baby soap meets these requirements to the greatest extent.
Children should be taught to wash their hands, face, neck and legs (in the evening) every morning and evening before going to bed, and during the day to thoroughly wash their hands before eating, after using the restroom, performing self-care work in the school building and on the site, and playing with animals. Children should be taught to especially carefully, using soapy brushes, to clean and rinse the subungual space and folds around the nails, where dirt, microorganisms and worm eggs most accumulate. It is recommended to cut the nails on the fingers and toes short: on the fingers - arched, along the elevation of the finger, and on the toes - straight. Incorrect cutting of nails at the corners contributes to their ingrowth into the fingers.
Each time after washing, hands must be wiped dry, otherwise cracks will appear on the skin and pimples will form. Each child must have their own towels for face, hands and feet. Sharing a towel can transmit infection. Compliance with the rules of personal hygiene includes at least weekly washing of the entire body with hot water at a temperature of 35-37 ° C and changing underwear. Hot water causes increased secretion from the sweat and sebaceous glands and dilation of the skin pores, which provides a greater opportunity to wash away dirt that gets into the pore openings. In addition to soap, when washing the skin, various types of washcloths play an important role in cleaning it. Bed linen is changed every 10-14 days. It should be boiled and lightly starched.
A number of special measures are used to prevent sweating of the feet in children and adolescents. Sweating can be caused by a number of reasons: rarely washing your feet, overheating them, wearing rubber shoes without insoles, etc. Proper care can eliminate sweating. First of all, this means washing your feet daily, first with warm and then with cool water. If sweating feet persists, then it is obviously associated with some disease. In such cases, it is necessary to consult a doctor as soon as possible.
Scalp hair also requires constant care. They usually become dirty quickly due to the abundant secretion of sebum. Along with dust and dirt, insects that cause skin diseases can enter the hair. The itching of the skin they cause leads to scratching and infection of other areas of the head. Children are recommended to wash oily hair every 5-6 days, dry hair every 10-12. Soft water rinses hair better, so if there is a need to soften the water, add one teaspoon of baking soda to it. It is advisable to wash oily hair with special types of shampoos or certain types of soap (green, sulfur, tar), alternating their use with baby soap.
Each child should use only his own fine-toothed comb and comb. A fine comb is used only after combing, otherwise you can pull out a lot of hair. Combs should be chosen with non-sharp teeth so that when combing your hair you do not damage or irritate your scalp.
Before each wash, combs should be thoroughly washed with a brush and soap. Girls are not recommended to tightly pull their hair, as this contributes to hair loss. Constantly wearing hats even indoors has a negative effect on hair.
Hair, even short ones, requires constant monitoring, and if necessary, insect killers and nit shell-dissolving agents must be immediately used.
Prevention of skin diseases. Prevention of skin diseases is, first of all, following all hygienic rules for caring for skin, hair, nails, being careful when playing with stray pets, and keeping your classroom and workplace clean at school, and your corner at home.
When organizing socially useful productive work for students at poultry farms and livestock farms on collective farms (state farms), school teachers are obliged to know whether the animals and birds are healthy and whether they are affected by any diseases, including fungal ones.
Neglect of skin care rules leads to a decrease in its protective properties, creating favorable conditions for the proliferation of pathogenic microbes, fungi, and the introduction of scabies mites . Pustular lesions and skin eczema, scabies, ringworm, and scab develop.
Pustular Skin diseases are caused by cocci, most often staphylo- and streptococci. In addition to following the rules of personal hygiene, attention is paid to the preventive treatment of minor wounds (scratches, abrasions, cuts) in children with disinfecting liquids and a 1% alcohol solution of brilliant green. Children with such diseases are isolated and treated. Attending school is permitted only after recovery and presentation of a doctor’s certificate confirming recovery. Baths and showers are temporarily canceled.
Scabies- a contagious disease transmitted from sick to healthy by scabies mite. In children's institutions, especially in boarding schools, scabies can take on the character of a mass disease. The scabies mite penetrates the skin and makes passages in it. The disease is accompanied by severe itching. Children scratch the skin until it bleeds and often introduce an additional infection, most often a pustular infection. Infection occurs through contact with sick people and animals, or through the use of the patient’s belongings (underwear, gloves). If scabies is detected, patients are isolated. In boarding schools, children are placed in isolation and given anti-scabies treatment. The clothes and personal belongings of sick people are disinfected or boiled. All other children in the boarding school are subjected to a thorough preventive examination.

In this part we are talking about age-related features of breathing regulation: about the morphological and functional features of the respiratory center, about the mechanism of breathing regulation in a child.

Age-related features of breathing regulation.

Morphological and functional features of the respiratory center.

In the fetus and infant, the structures of the respiratory center are not fully mature morphologically and functionally. Each stage of development corresponds to its own level of maturity of regulatory mechanisms that ensure the adaptation of the developing organism to the conditions of existence.

The respiratory movements of the fetus are regulated mainly by the bulbar part of the respiratory center.

The excitability of the respiratory center and its sensitivity to the gas composition of the blood in the fetus, newborns and infants is low. This is evidenced by the presence of an irregular rhythm of breathing movements. The activity of neurons in the respiratory center and their excitability at school age becomes the same as in adults.

During puberty, adolescents experience an increase in the excitability of the respiratory center, and therefore the coordination of the functions of the respiratory apparatus deteriorates. At the end of puberty, respiratory function returns to normal.

The peculiarity of the fetal respiratory center is that its cells do not respond to an increase in CO 2 content in the blood, but are sensitive to a decrease in oxygen content (hypoxemia). Chemoreceptors of the carotid sinus and aortic arch do not respond to increased carbon dioxide levels. The sensitivity of the respiratory center to CO 2 content increases with age: in adolescents 9-16 years old and in adults it is approximately the same.

Voluntary regulation of breathing, and therefore cortical regulation, develops along with speech in the first years of a child’s life.

The mechanism of breathing regulation in a child.

To carry out the act of respiration, the blood of the fetus must have a certain content of oxygen and CO 2. If, through hyperventilation, the CO 2 content in the mother’s blood is reduced, then the fetal respiratory movements decrease until they cease completely. Fetal breathing is negatively affected by increased oxygen levels in its blood. So, if the O2 content in the mother’s blood is increased by inhaling pure oxygen, then the fetus stops breathing and the heart rate decreases. After prolonged cessation of breathing, the fetus develops rare respiratory movements, repeating after 2-3 minutes.

If the mother inhales a gas mixture with a lower content of O 2 (16%), then the fetus's breathing improves - deeper respiratory movements occur.

The respiratory center is highly sensitive to low oxygen levels in the blood. With hypoxemia in the fetus, the frequency and depth of respiratory movements increase and typical changes occur in the cardiovascular system (heart rate increases, blood pressure rises and blood turnover rate increases). It has been established that the fetus reacts to hypoxemia with the same reaction even if the influence of the vagus and sinocarotid nerves is excluded.

Studies of this kind give reason to conclude that the mechanism of adaptation of the fetus to hypoxemia is different than that of an adult. In an adult, this reaction is carried out reflexively through the chemoreceptors of the carotid and aortic zones, and in the fetus it has a central origin. Hypoxemic blood of the fetus washes the cells of the respiratory center and the center of sympathetic regulation of the heart, which entails an increase in the frequency and amplitude of breathing and changes in the cardiovascular system.

Adaptation to hypoxemia in the fetus is not accompanied by an increase in the oxygen capacity of the blood. Research has established that in the hypoxemic state of the fetus, which develops as a result of hypoxemia in the mother, the number of red blood cells in the blood does not increase, which is the case in an adult organism.

The reduced sensitivity of the cells of the respiratory center to the content of CO 2 in the blood persists in a newborn, an infant and during the first years of life.