§2. The regulation of respiration and its age features

Respiratory center. Respiration is controlled by the central nervous system, whose special areas determine automatic respiration - alternating inhalation and exhalation and arbitrary breathing, which provides adaptive changes in the respiratory system, corresponding to a specific external situation and ongoing activities. 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: impulses of excitation rhythmically arise in it. These impulses arise automatically. Even after the complete shutdown of the centripetal pathways leading to the respiratory center, rhythmic activity can be registered in it. The automatism of the respiratory center is associated with the process of metabolism in it. Rhythmic impulses are transmitted from the respiratory center through centrifugal neurons to the intercostal muscles and diaphragm, providing a consistent 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. The 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 carbon dioxide concentration, and mechanoreceptors lungs and respiratory muscles. Airway receptors also influence the regulation of respiration. 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 depend to a greater extent on them. When you inhale, when the lungs are stretched, 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 descends, the diaphragm takes the form of a dome, the volume of the chest decreases and exhalation occurs. Exhalation, in turn, reflexively stimulates inspiration. The cerebral cortex takes part in the regulation of respiration, which provides the finest adaptation of respiration to the needs of the body in connection with changes in environmental conditions and the life of the body. A person can arbitrarily, at will, hold his breath for a while, change the rhythm and depth of respiratory movements. The influence of the cerebral cortex explains the pre-start changes in breathing in athletes - a significant deepening and quickening of breathing before the start of the competition. It is possible to develop conditioned respiratory reflexes. If 5-7% of carbon dioxide is added to the inhaled air, which in such a concentration speeds up breathing, and the breath is accompanied by the beat of a metronome or a bell, then after several combinations, just a bell or a beat of a metronome will cause an increase in breathing. Humoral effects 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 causes irritation of receptors in blood vessels, carrying blood to the head, and reflexively excites the respiratory center. Other acidic products that enter the blood act in a similar way, such as lactic acid, the content of which in the blood increases during muscular work. Features of the regulation of breathing 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 by the time of birth the functional formation of the respiratory center has not yet ended. This is evidenced by a large variability in the frequency, depth, rhythm of breathing in children. early age. The excitability of the respiratory center in newborns and infants is low. Children of the first years of life are more resistant to lack of oxygen (hypoxia) than older children. The formation of the functional activity of the respiratory center occurs with age. By the age of 11, the possibility of adapting breathing to various conditions of life is already well expressed. The sensitivity of the respiratory center to the content of carbon dioxide increases with age and at school age reaches approximately the level of adults. It should be noted that during puberty there are temporary violations of the regulation of breathing and the body of adolescents is less resistant to oxygen deficiency than the body of an adult. The need for oxygen, which increases with the growth and development of the organism, is provided by the improvement of the regulation of the respiratory apparatus, leading to an increasing economization of its activity. As the cerebral cortex matures, the ability to arbitrarily change breathing improves - to suppress respiratory movements or to produce maximum ventilation of the lungs. In an adult, during muscular work, pulmonary ventilation increases due to the increase and deepening of breathing. Activities such as running, swimming, skating, skiing, and cycling dramatically increase pulmonary ventilation. In trained people, the increase in pulmonary gas exchange occurs mainly due to an increase in the depth of breathing. Children, due to the peculiarities of their respiratory apparatus, cannot significantly change the depth of breathing during physical exertion, but increase their breathing. The already frequent and shallow breathing in children during physical exertion becomes even more frequent and superficial. This results in lower ventilation efficiency, especially in young children. The body of a teenager, unlike an adult, reaches the maximum level of oxygen consumption faster, but also stops working faster due to the inability to maintain oxygen consumption for a long time. high level. Voluntary changes in breathing play an important role in 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 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 tasks of the teacher. One of the conditions for proper breathing is care for the development chest. For this, the correct position of the body is important, especially while sitting at a desk, breathing exercises and other physical exercises that develop the muscles that move the chest. Especially useful in this regard are sports such as swimming, rowing, skating, skiing. Usually a person with well-developed chest, breathes evenly and correctly. It is necessary to teach children to walk and stand in a straight posture, as this contributes to the expansion of the chest, facilitates the activity 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 in the process various kinds activity promotes the expansion of the chest, facilitates deep breathing. On the contrary, when the body is bent, the opposite conditions are created, the normal activity of the lungs is disturbed, they absorb less air, and at the same time oxygen. Education in children and adolescents of proper breathing through the nose in a state of relative rest, during work and exercise, is given great attention in the process of physical education. Breathing exercises, swimming, rowing, skating, skiing especially help to improve breathing. Respiratory gymnastics is also of great health significance. With a calm and deep breath, intra-thoracic pressure decreases, as the diaphragm descends. The flow of venous blood to the right atrium increases, which facilitates the work of the heart. The diaphragm descending during inhalation massages the liver and upper organs abdominal cavity, helps to remove metabolic products from them, and from the liver - venous stagnant blood and bile. During deep exhalation, the diaphragm rises, which increases the outflow venous blood from lower extremities, pelvis and abdomen. As a result, blood circulation is facilitated. At the same time, with a deep exhalation, a slight massage of the heart occurs and its blood supply improves. In respiratory gymnastics, there are three main types of breathing, named according to the form of execution - chest, abdominal and full breathing. The most complete for health is considered full breath. There are various complexes of respiratory gymnastics. These complexes are recommended to be performed up to 3 times a day, at least an hour after eating. Hygienic value of indoor air. Air purity and its physical and chemical properties are of great importance for the health and performance of children and adolescents. The stay of children and adolescents in a dusty, poorly ventilated room is the cause of not only the deterioration of 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 physical and chemical properties deteriorate sharply. For the human body, the content of positive and negative ions in the air is not indifferent. In atmospheric air, the number of positive and negative ions is almost the same, light ions significantly predominate over heavy ones. Studies have shown that light and negative ions favorably affect a person, and their number in work areas is gradually decreasing. Positive and heavy ions begin to predominate, which depress human vital activity. In schools, before lessons, 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 first decreases to 220, and the second increases to 24 thousand. The beneficial physiological effect of negative air ions was the basis for the use of artificial air ionization closed premises of children's institutions, sports halls. Sessions of a short (10 min) 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, an increase in air temperature and humidity in classrooms, the concentration of carbon dioxide increases, ammonia and various organic substances accumulate. The deterioration of the physical and chemical properties of the air, especially in rooms with a reduced height, entails a significant deterioration in the performance of the cells of the human cerebral cortex. From the beginning to the end of the classes, the dust content of the air and its bacterial contamination increase, especially if by the beginning of the classes the premises were not cleaned with a wet method and aired. The number of colonies of microorganisms in 1 m 3 of air in such conditions by the end of classes on the second shift increases by 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 emitted by students increases by 2-3 times, the required volume of air that needs to be provided in the gym, in workshops, accordingly increases to 10-15 m 3. Accordingly, the area per student also 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. The exchange of air occurs through the pores of the building material, the gaps in the frames of windows, in the doors due to the difference in temperature and pressure inside and outside the room. However, this exchange is limited and insufficient. The supply and exhaust artificial ventilation in children's institutions has not justified itself. Therefore, the central exhaust ventilation device with wide aeration - the 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 the outside air enters upwards through them, which ensures effective air exchange in the room. Through ventilation is 5-10 times more efficient than usual. With cross-ventilation, the content of microorganisms in the indoor air also sharply decreases. The current norms and rules provide for natural exhaust ventilation in the amount of a single exchange per 1 hour. It is assumed that the rest of the air is removed through recreational facilities, followed by exhaust from sanitary facilities and through fume hoods of chemistry laboratories. In the workshops, the air flow should provide 20 m 3 / h, in sports halls - 80 m 3 / h per student. In the chemical and physical laboratories and in the carpentry workshop, additional fume hoods are arranged. In order to combat dust, at least once a month, general cleaning should be carried out with washing of panels, radiators, window sills, doors, and thorough wiping of furniture. Microclimate. Temperature, humidity and air velocity (cooling force) in the classroom characterize its microclimate. The value of the optimal microclimate for the health and performance of students and teachers is no less than other parameters of the sanitary condition and maintenance of the classrooms of the school and vocational schools. In connection with the increase in the temperature of the outdoor air and the air in the room, a decrease in working capacity was noticed in schoolchildren. In different seasons of the year, children and adolescents show peculiar changes in attention and memory. The relationship between fluctuations in outdoor temperature and the performance of children partly served as the basis for setting the dates for the beginning and end of the school year. best time autumn and winter are considered for training sessions. During the training sessions, even at a negative outside temperature, the temperature in the classrooms rises by 4 ° before the big break, and by 5.5 ° by the end of the session. Temperature fluctuations, of course, affect the thermal state of students, which is reflected in changes in the temperature of the skin of the limbs (feet and hands). The temperature of these areas of the body rises with increasing air temperature. High temperature in classrooms (up to 26°C) leads to tension in thermoregulatory processes and reduced performance. In such conditions, the mental performance of students by the end of the lessons is sharply reduced. The influence of temperature conditions on the working capacity of students during physical education and labor is even more clearly manifested. In the premises of schools, boarding schools, boarding schools at schools, vocational schools with a relative humidity of 40-60% and an air velocity of no more than 0.2 m / s, its temperatures are normalized in accordance with climatic regions (Table 19), the air temperature in the room both vertically and horizontally is set within 2-3°С. The low air temperature in the sports hall, workshops and recreational areas corresponds to the type of activity of children and adolescents in these areas.

During training sessions, special care should be taken for the thermal comfort of students sitting in the first row from the windows, strictly observe the established breaks, and do not seat children near radiators (stoves). In schools with strip glazing, the gaps between the first row of desks and windows in winter should be increased to 1.0-1.2 m. radiation and convection cooling. Already at an outside air temperature below -15°C, the temperature of the inner surface of the glass decreases 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 a large heat capacity, ensures a uniform air temperature in the room during the day, does not make the air too dry and eliminates the sublimation of dust on the heating devices. Of the local heating devices, Dutch stoves are used, which have a large heat capacity. The stoves are fired from the corridors at night, and the pipes are closed no later than 2 hours before the students arrive.

Respiratory center. The regulation of respiration is carried out by the central nervous system, special areas of which determine automatic respiration - alternating inhalation and exhalation and arbitrary breathing, which provides adaptive changes in the respiratory system, corresponding to a specific external situation and ongoing activities. 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: impulses of excitation rhythmically arise in it. These impulses arise automatically. Even after the complete shutdown of the centripetal pathways leading to the respiratory center, rhythmic activity can be registered in it. The automatism of the respiratory center is associated with the process of metabolism in it. Rhythmic impulses are transmitted from the respiratory center through centrifugal neurons to the intercostal muscles and diaphragm, providing a consistent 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. The 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 carbon dioxide concentration, and mechanoreceptors lungs and respiratory muscles. Airway receptors also influence the regulation of respiration. 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 depend to a greater extent on them. When you inhale, when the lungs are stretched, 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 descends, the diaphragm takes the form of a dome, the volume of the chest decreases and exhalation occurs. Exhalation, in turn, reflexively stimulates inspiration. The cerebral cortex takes part in the regulation of respiration, which provides the finest adaptation of respiration to the needs of the body in connection with changes in environmental conditions and the life of the body. A person can arbitrarily, at will, hold his breath for a while, change the rhythm and depth of respiratory movements. The influence of the cerebral cortex explains the pre-start changes in breathing in athletes - a significant deepening and quickening of breathing before the start of the competition. It is possible to develop conditioned respiratory reflexes. If 5-7% of carbon dioxide is added to the inhaled air, which in such a concentration speeds up breathing, and the breath is accompanied by the beat of a metronome or a bell, then after several combinations, just a bell or a beat of a metronome will cause an increase in breathing. Humoral effects on the respiratory center. It has a great influence on the state of the respiratory center chemical composition blood, in particular its gas composition. The accumulation of carbon dioxide in the blood causes irritation of the receptors in the blood vessels that carry blood to the head, and reflexively excites the respiratory center. Other acidic products that enter the blood act in a similar way, such as lactic acid, the content of which in the blood increases during muscular work. Features of the regulation of respiration 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 by the time of birth the functional formation of the respiratory center has not yet ended. This is evidenced by the large variability in the frequency, depth, rhythm of breathing in young children. The excitability of the respiratory center in newborns and infants is low. Children of the first years of life are more resistant to lack of oxygen (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 different conditions vital activity. The sensitivity of the respiratory center to the content of carbon dioxide increases with age and at school age reaches approximately the level of adults. It should be noted that during puberty there are temporary violations of the regulation of breathing and the body of adolescents is less resistant to oxygen deficiency than the body of an adult. The need for oxygen, which increases with the growth and development of the organism, is provided by the improvement of the regulation of the respiratory apparatus, leading to an increasing economization of its activity. As the cerebral cortex matures, the ability to arbitrarily change breathing improves - to suppress respiratory movements or to produce maximum ventilation of the lungs. In an adult, during muscular work, pulmonary ventilation increases due to the increase and deepening of breathing. Activities such as running, swimming, skating, skiing, and cycling dramatically increase pulmonary ventilation. In trained people, the increase in pulmonary gas exchange occurs mainly due to an increase in the depth of breathing. Children, due to the peculiarities of their respiratory apparatus, cannot significantly change the depth of breathing during physical exertion, but increase their breathing. The already frequent and shallow breathing in children during physical exertion becomes even more frequent and superficial. This results in lower ventilation efficiency, especially in young children. The body of a teenager, unlike an adult, reaches the maximum level of oxygen consumption faster, 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 in 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 the 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 tasks of the teacher. One of the conditions for proper breathing is taking care of the development of the chest. For this, the correct position of the body is important, especially while sitting at a desk, breathing exercises and other physical exercises that develop the muscles that move the chest. Especially useful in this regard are sports such as swimming, rowing, skating, skiing. Usually a person with well-developed chest, breathes evenly and correctly. It is necessary to teach children to walk and stand in a straight posture, as this contributes to the expansion of the chest, facilitates the activity 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 in the process of various activities promotes expansion of the chest, facilitates deep breathing. On the contrary, when the body is bent, the opposite conditions are created, the normal activity of the lungs is disturbed, they absorb less air, and at the same time oxygen. Education in children and adolescents of proper breathing through the nose in a state of relative rest, during work and exercise, is given great attention in the process of physical education. Breathing exercises, swimming, rowing, skating, skiing especially help to improve breathing. Respiratory gymnastics is also of great health significance. With a calm and deep breath, intra-thoracic pressure decreases, as the diaphragm descends. The flow of venous blood to the right atrium increases, which facilitates the work of the heart. The diaphragm descending during inhalation massages the liver and upper abdominal organs, helps to 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 slight massage of the heart occurs and its blood supply improves. In respiratory gymnastics, there are three main types of breathing, named according to the form of execution - chest, abdominal and full breathing. The most complete for health is considered full breath. There are various complexes of respiratory gymnastics. These complexes are recommended to be performed up to 3 times a day, at least an hour after eating. Hygienic value of indoor air. Air purity and its physical and chemical properties are of great importance for the health and performance of children and adolescents.

PECULIARITIES OF RESPIRATORY REGULATION IN CHILDREN OF DIFFERENT AGES

CHARACTERISTICS OF THE RESPIRATORY ORGANS OF THE FETUS AND NEWBORN, THE MECHANISM OF THE FIRST INHALATION. INDICATORS OF LUNG VENTILATION. FEATURES OF GAS EXCHANGE IN THE LUNG AND BLOOD GAS TRANSPORT IN A NEWBORN.

Long before birth, the fetal chest makes 38-70 rhythmic movements per minute. With hypoxemia, they can intensify. During these movements, the lung tissue remains collapsed, however, negative pressure is created between the sheets of the pleura when the chest expands. Fluctuations in the pressure of the chest cavity of the fetus create favorable conditions for blood flow to the heart. With rhythmic movements of the chest, the respiratory tract of the fetus can get amniotic fluid especially when the baby is born in asphyxia. In these cases, before starting artificial respiration, fluid from the airways is sucked off.

The first independent breath immediately after birth is the beginning of its own gas exchange in the lungs of the child. The mechanism of occurrence of the first breath of a newborn consists of many factors. The main ones are: the cessation of gas exchange through the placenta in connection with the ligation of the umbilical cord, as a result of which hypoxia and hypercapnia develop; reflex irritation of thermo- and mechanoreceptors of the skin and mucous membranes of the newborn by environmental factors. As a rule, after birth, after 1-3 respiratory movements, the lung tissue becomes evenly transparent. With the onset of pulmonary respiration, blood circulation through the pulmonary circulation changes due to a decrease in resistance in the pulmonary artery.

After birth, the content of gases in the blood of a child changes, but it still differs significantly from the gas composition of the blood of an adult. The content of oxygen and carbon dioxide in the blood of children is lower than that of adults. There is a state of physiological hypoxemia and hypocapnia.

Due to the immaturity of the respiratory apparatus and, accordingly, the inefficiency of costal breathing, diaphragmatic breathing occurs in newborns.

The morphological features of the child's breathing during the first days of life are associated with narrow nasal passages, which makes it difficult to breathe through the nose. At the same time, the ribs in newborns are located at right angles to the spine, and the intercostal muscles are not yet sufficiently developed, and therefore breathing is shallow and frequent. With age, there is a decrease in the angle of inclination of the ribs in relation to the spine, and accordingly, the volume of the lungs increases. In this regard, the depth of breathing increases and the respiratory rate decreases from 30–70 breaths per minute in newborns to 12–18 in adults.

The relatively large liver makes it difficult to move the diaphragm, and therefore the volume of breathing is small. In the future, the type of breathing is set individually and, based on gender, becomes predominantly diaphragmatic, chest or mixed.

During the maturation of the organs of the respiratory system, there is a change in the types of breathing: in infants, breathing is chest-abdominal, at 3-7 years old - chest. At 7-8 years of age, gender differences in the types of breathing appear. By the age of 14-17, boys have the most effective abdominal breathing, and girls have chest breathing. In this case, the type of breathing can change based on sports activities.

The respiratory system of a child is characterized by a number of morphological and functional features due to the incompleteness of the formation of the bronchopulmonary apparatus. The development of the child's lungs consists in an increase in their size, in the predominance of alveoli and alveolar passages, an increase in the capacity of the alveoli and elastic elements in the connective tissue layers. An increase in the size of the lungs occurs up to 16 years. The most intensive growth is noted in the first 3 months and in the period from 13 to 16 years. The respiratory surface of the lungs in children is relatively larger than in adults.

The chest of young children is always in a state of maximum inspiration - the ribs are located at right angles to the spine, in connection with this, compensation for oxygen deficiency by deepening breathing is almost impossible. Actually, the respiratory muscles in newborns are poorly developed, in connection with this, the abdominal muscles participate in the respiratory act from the first hours after birth.

The frequency of respiratory movements in children decreases with age.

The capacity of the lungs also changes. The latter can be judged by a number of indicators. Most often, a change in lung capacity (VC) is used. In the first years of a child's life, the measurement of VC is impossible, since this requires an arbitrarily deepening of breathing, which a child cannot do until about 4-6 years of age. VC reaches the level of adults by the age of 16-17. It is usually higher in men than in women.

Minute respiratory volume increases with age. Due to the fact that in children under one year of age, respiratory movements are very frequent, their respiratory efficiency is correspondingly less, as evidenced by the gas composition of exhaled and alveolar air. Only by the age of 14 do these indicators approach the values ​​characteristic of an adult. During the entire first year of life, the child is in a state of physiological shortness of breath.

Protection of newborns from hypoxia is poorly developed. At the same time, the resistance of nerve cells to hypoxia is higher in them than in adults. Newborn children can endure such degrees of hypoxia in which adults die.

Pulmonary ventilation. At rest in an adult, this value is 5-6 l / min. In a newborn child, the minute respiratory volume is 650-700 ml / min, by the end of 1 year of life it reaches 2.6-2.7 l / min, by 6 years - 3.5 l / min, at 10 years - 4.3 l / min, and in adolescents - 4.9 l / min. During physical exertion, the minute volume of breathing can increase very significantly, reaching 100 l / min or more in young men and adults.

In newborns, the frequency of breathing is still irregular. A series of frequent breaths alternate with rare ones, sometimes there are deep breaths. Sudden pauses in breathing are also possible, which is explained by the low sensitivity of the neurons of the respiratory center (in the medulla oblongata) to the content of CO 2 and partially O 2. For this reason, newborns and infants are more resistant to hypoxia (lack of oxygen). The sensitivity of the neurons of the respiratory center to the content of CO2 increases with age, reaching the level of the ʼʼʼʼʼ state by the age of 7–8 years. By the age of 11, the adaptability of breathing to various conditions is already well expressed.

During puberty, there is a slight violation of the regulation of respiration and a decrease in resistance to lack of oxygen. Children and adolescents are less able than adults to hold their breath and work in oxygen deficient conditions. For this reason, the purity of the air and its physical and chemical properties, which depend on the air temperature in the room, are of great importance for the health and maintenance of high performance of children and adolescents.

Due to the immaturity of the nerve centers and the receptor apparatus in newborns, the excitability of the respiratory center is significantly reduced. Chemoreceptors in the carotid sinus and aortic arch begin to function from about 15-18 days after birth. The low excitability of the respiratory center persists for quite a long time. Only by the school period does it reach normal values ​​for an adult. During puberty, one can detect a slight increase in the excitability of the respiratory center. In adolescents during this period, there is an increased sensitivity to a lack of oxygen.

Features of the regulation of breathing in children are associated with the gradual formation of the respiratory center. In a newborn child, the respiratory period is irregular: frequent breathing alternates with rare breathing, deep breaths occur about 1 time per minute, sometimes breath holding occurs for 3 or more seconds. This is especially common during REM sleep. An increase in pulmonary ventilation due to an increase in CO 2 in the inhaled air is much less pronounced than in adults, and is carried out through central chemoreceptors.

In children with a reduced response to CO 2, prolonged breath holding occurs during sleep. This is the cause of sudden death in children. With age, the increase in lung ventilation in response to hypercapnia and hypoxia increases, but even by the age of 8-9 years, the reaction in response to hypercapnia and hypoxia in children is almost two times weaker than in adults.

In children of primary school age, reduced sensitivity to excess CO 2 and lack of O 2 remains. During puberty, the opposite phenomenon is observed. As the child grows, the regulation of breathing improves due to the development of peripheral receptors and the pneumotaxis center in the pons. There is an ability to voluntary control of breathing, a conditioned reflex increase in pulmonary ventilation before physical exertion. At the same time, children at the age of 7-8 and even at 12-14 years of age should combine physical activity with rest, and only by the age of 17-18 are teenagers capable of long-term muscular work.

Voluntary regulation of breathing develops along with the development of speech. Improvement of this regulation is noted in the first years of life.

FEATURES OF REGULATION OF RESPIRATION IN CHILDREN OF DIFFERENT AGES - concept and types. Classification and features of the category "FEATURES OF RESPIRATORY REGULATION IN CHILDREN OF DIFFERENT AGES" 2017, 2018.

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SMOLENSK STATE ACADEMY

PHYSICAL CULTURE OF SPORTS AND TOURISM

Topic: Age-related features of breathing

Fulfilled

student group 1-2-07

Darevsky P.I

Smolensk 2012

THE SIGNIFICANCE OF BREATHING

Breathing is a vital process of constant exchange of gases between the body and its external environment.

Almost all complex reactions of the transformation of substances in the body occur with the obligatory participation of oxygen. Without oxygen, metabolism is impossible, and a constant supply of oxygen is necessary to preserve life.

During oxidative processes, decay products are formed, including carbon dioxide, which are removed from the body.

When breathing, gases are exchanged between the body and the environment, which ensures a constant supply of oxygen to the body and the removal of carbon dioxide from it. This process takes place in the lungs. The carrier of oxygen from the lungs to the tissues, and carbon dioxide from the tissues to the lungs is the blood.

STRUCTURE OF THE RESPIRATORY ORGANS

Nasal cavity. In the respiratory organs, airways are distinguished, through which the inhaled and exhaled air passes, and the lungs, where gas exchange takes place between air and blood. The respiratory tract begins with the nasal cavity, separated from the oral cavity by a septum: in front - the hard palate, and behind - the soft palate. Air enters the nasal cavity through the nasal openings - the nostrils. At the outer edge of them are hairs that protect against dust from entering the nose. The nasal cavity is divided by a septum into the right and left halves, each of which is divided by the turbinates into the lower, middle and upper nasal passages.

In the first days of life, breathing in children through the nose is difficult. The nasal passages in children are narrower than in adults, and are finally formed by the age of 14-15.

The mucous membrane of the nasal cavity is abundantly supplied with blood vessels and is covered with multi-row ciliated epithelium. There are many glands in the epithelium that secrete mucus, which, together with dust particles that have penetrated with the inhaled air, is removed by the flickering movements of the cilia. In the nasal cavity, the inhaled air is warmed, partially cleaned of dust and moistened.

The nasal cavity behind through openings - choanas - communicates with the nasopharynx.

Nasopharynx. The nasopharynx is the upper part of the pharynx. The pharynx is a muscular tube into which the nasal cavity, oral cavity and larynx open. In the nasopharynx, in addition to the choanae, the auditory tubes open, connecting the pharyngeal cavity with the cavity of the middle ear. From the nasopharynx, air passes into the oral part of the pharynx and further into the larynx.

The pharynx in children is wide and short, auditory tube is located low. Diseases of the upper respiratory tract are often complicated by inflammation of the middle ear, since the infection easily penetrates into the middle ear through a wide and short auditory tube.

Larynx. The skeleton of the larynx is formed by several cartilages interconnected by joints, ligaments and muscles. The largest of these is the thyroid cartilage. Above the entrance to the larynx is a cartilaginous plate - the epiglottis. It acts as a valve that closes the entrance to the larynx when swallowing.

The cavity of the larynx 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 covers the vocal cords. The space between the vocal cords is called the glottis. Thus, the larynx not only connects the pharynx with the trachea, but also participates in the speech function.

During normal breathing, the vocal cords are relaxed and the gap between them narrows. Exhaled air, passing through a narrow gap, causes the vocal cords to vibrate - a sound is produced. The pitch of the tone depends on the degree of tension of the vocal cords: with strained cords, the sound is higher, with relaxed ones, lower. The movements of the tongue, lips and cheeks, the contraction of the muscles of the larynx itself contribute to the trembling of the vocal cords and the formation of sounds.

The larynx in children is shorter, narrower and higher than in adults. The larynx grows most intensively in the 1-3 years of life and during puberty.

At the age of 12-14, in boys, at the junction of the plates of the thyroid cartilage, the Adam's apple begins to grow, the vocal cords lengthen, the entire larynx becomes wider and longer than in girls. In boys, during this period, there is a breaking of the voice.

Trachea and bronchi. The trachea departs from the lower edge of the larynx. This is a hollow, non-collapsing tube (in an adult) about 10–13 cm long. Inside, the trachea is lined with a mucous membrane. The epithelium here is multi-row, ciliated. Behind the trachea is the esophagus. At the level of IV-V thoracic vertebrae, the trachea divides into the right and left primary bronchi.

The bronchi are similar in structure to the trachea. The right bronchus is shorter than the left. The primary bronchus, having entered the gates of the lungs, is divided into bronchi of the second, third and other orders, which form the bronchial tree. The thinnest branches are called bronchioles.

In newborns, the trachea is narrow and short, its length is 4 cm; by the age of 14-15, the length of the trachea is 7 cm.

Lungs. Thin bronchioles enter the lung lobules and within them divide into terminal bronchioles. Bronchioles branch into alveolar passages with sacs, the walls of which are formed by many pulmonary vesicles - alveoli. The alveoli are the final part of the airway. The walls of the pulmonary vesicles consist of a single layer of squamous epithelial cells. Each alveolus is surrounded on the outside by a dense network of capillaries. Through the walls of the alveoli and capillaries there is an exchange of gases -? oxygen passes from the air into the blood, and carbon dioxide and water vapor enter the alveoli from the blood.

In the lungs, there are up to 350 million alveoli, and their surface reaches 150 m2. The large surface of the alveoli contributes to better gas exchange. On one side of this surface is alveolar air, constantly renewing in its composition, on the other - blood continuously flowing through the vessels. Diffusion of oxygen and carbon dioxide occurs through the vast surface of the alveoli. During physical work, when the alveoli are significantly stretched with deep breaths, the size of the respiratory surface increases. The larger the total surface of the alveoli, the more intense the diffusion of gases occurs.

Each lung is covered with a serous membrane called the pleura. The pleura has two leaves. One is tightly fused with the lung, the other is attached to the chest. Between both sheets there is a small pleural cavity filled with serous fluid (about 1-2 ml), which facilitates the sliding of the pleural sheets during respiratory movements.

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 three years, increased growth of the lungs and differentiation of their individual elements occur. The number of alveoli by the age of eight reaches the number of them in an adult. Between the ages of 3 and 7 years, the growth rate of the lungs decreases. Alveoli grow especially vigorously after 12 years. The volume of the lungs by the age of 12 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).

RESPIRATORY MOVEMENTS

Acts of inhalation and exhalation. Due to the rhythmically performed acts of inhalation and exhalation, an exchange of gases takes place between atmospheric and alveolar air located in the pulmonary vesicles.

Not in the lungs muscle tissue, and therefore they cannot actively contract. An active role in the act of inhalation and exhalation belongs to the respiratory muscles. With paralysis of the respiratory muscles, 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 take them somewhat to the side. This increases the volume of the chest. When the diaphragm contracts, its dome flattens, which also leads to an increase in the volume of the chest. With deep breathing, other muscles of the chest and neck also take part. 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 facilitated by negative pressure in the chest cavity. Negative pressure is pressure below atmospheric pressure.

During inhalation, it is lower than atmospheric by 9-12 mm Hg, and during exhalation - by 2-6 mm Hg.

During development, the chest grows faster than the lungs, which is why the lungs are constantly (even when exhaling) stretched. The stretched elastic lung tissue tends to shrink. The force with which lung tissue tends to shrink due to elasticity counteracts atmospheric pressure. Around the lungs pleural cavity, a pressure equal to atmospheric pressure minus the elastic recoil 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 expanded chest. The lungs are stretched. Atmospheric pressure acts on the lungs from the inside through the airways, stretches them, 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 into the lungs through the respiratory tract. The more the volume of the chest increases during inhalation, the more the lungs are stretched, the deeper the inhalation.

When the respiratory muscles relax, the ribs descend to their original position, the dome of the diaphragm rises, the volume of the chest, and, consequently, the lungs decreases, and air is exhaled outward. In a deep, exhalation, the abdominal muscles, internal intercostal and other muscles take part.

Breath 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 high, the intercostal muscles are weak. In connection with such features, diaphragmatic breathing prevails in newborns with little 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 difficult cage descends and the ribs take on an oblique position. The breathing of infants now becomes chest-abdominal, with a predominance of diaphragmatic, and in upper section chest mobility is still small.

At the age of 3 to 7 years, due to the development of the shoulder girdle, the thoracic type of breathing increasingly begins to predominate, and by the age of seven it becomes pronounced.

At the age of 7-8, gender differences in the type of breathing begin: in boys, the abdominal type of breathing becomes predominant, in girls - chest. Sexual differentiation of respiration ends at 14-17 years of age. It should be noted that the type of breathing in boys and girls may vary depending on sports, work activities.

Due to the peculiarity of the structure of the chest and the low endurance of the respiratory muscles, the respiratory movements in children are less deep and frequent.

Depth and frequency of breathing. An adult makes an average of 15-17 respiratory movements per minute; in one breath with calm breathing inhales 500 ml of air. During muscular work, breathing quickens by 2-3 times. With some types of sports exercises, the respiratory rate reaches 40-45 times per minute.

In trained people, with the same work, the volume of pulmonary ventilation gradually increases, as breathing becomes rarer, but deeper. With deep breathing, alveolar air is ventilated by 80-90%, which ensures greater diffusion of gases through the alveoli. With shallow and frequent breathing, the ventilation of the alveolar air is much less and a relatively large part of the inhaled air remains in the so-called dead space - in the nasopharynx, oral cavity, trachea, bronchi. Thus, in trained people, the blood is more saturated with oxygen than in untrained people.

The depth of breathing is characterized by the volume of air entering the lungs in one breath - respiratory air.

The breathing of a newborn baby is frequent and shallow. The frequency is subject to significant fluctuations - 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 there is a further decrease in breathing (18-20 times per minute).

The high frequency of respiratory movements in the child provides high pulmonary ventilation.

The volume of respiratory air in a child at 1 month is 30 ml, at 1 year old - 70 ml, at 6 years old - 156 ml, at 10 years old - 230 ml, at 14 years old - 300 ml.

Due to the high respiratory rate in children, the minute volume of breathing (in terms of 1 kg of weight) is much higher than in adults. Minute respiratory volume is the amount of air that a person inhales in 1 minute; it is determined by the product of the value of respiratory air by the number of respiratory movements in 1 min. In a newborn, the minute volume of breathing is 650-700 ml of air, by the end of the first year of life - 2600-2700 ml, by the age of six - 3500 ml, in a 10-year-old child - 4300 ml, in a 14-year-old - 4900 ml, in an adult - 5000-6000 ml.

Vital capacity of the lungs. At rest, an adult can inhale and exhale a relatively constant volume of air (about 500 ml). But with increased breathing, you can inhale about 1500 ml of air. Similarly, after a normal exhalation, a person can still exhale 1500 ml of air. The maximum amount of air that a person can exhale after taking a deep breath is called the vital capacity.

The vital capacity of the lungs changes with age, it also depends on gender, the degree of development of the chest, and respiratory muscles. It is usually greater in men than in women; athletes have more than untrained people. For weightlifters, for example, it is about 4000 ml, for football players - 4200 ml, for gymnasts - 4300, for swimmers - 4900, for rowers - 5500 ml or more.

Since the measurement of 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, the vital capacity of the lungs reaches values ​​characteristic of an adult.

GAS EXCHANGE IN THE LUNGS

Composition of inhaled, exhaled and alveolar air.

By alternately inhaling and exhaling, a person ventilates the lungs, maintaining a relatively constant gas composition in the alveoli. A person breathes atmospheric air with a high oxygen content (20.9%) and a low carbon dioxide content (0.03%), and exhales air in which oxygen is 16.3% and carbon dioxide is 4%.

In the alveolar air, oxygen is 14.2%, and carbon dioxide is 5.2%.

Why is there more oxygen in exhaled air than in alveolar air? This is explained by the fact that during exhalation, the air that is in the respiratory organs, in the airways, is mixed with the alveolar air.

The lower efficiency of pulmonary ventilation in children is expressed in a different gas composition of both exhaled and alveolar air. The younger the children, the lower the percentage of carbon dioxide and the greater the percentage of oxygen in exhaled and alveolar air. Accordingly, they have a lower percentage of oxygen use. Therefore, to consume the same volume of oxygen and release the same volume of carbon dioxide, children need to ventilate their lungs more than adults.

Gas exchange in the lungs. In the lungs, oxygen from the alveolar air passes into the blood, and carbon dioxide from the blood enters the lungs. The movement of gases occurs according to the laws of diffusion, according to which a gas propagates from an environment with a high partial pressure to an environment with a lower pressure.

Partial pressure is the part of the total pressure that falls on the proportion of a given gas in gas mixture. The higher the percentage of gas in the mixture, the correspondingly higher its partial pressure.

For gases dissolved in a liquid, the term "voltage" is used, which corresponds to the term "partial pressure" used for free gases.

Gas exchange in the lungs takes place between alveolar air and blood. The alveoli of the lungs are surrounded by a dense network of capillaries. 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 the diffusion of gases is carried out, and the difference in the partial pressure (voltage) of the diffusing gases. Such conditions exist in the lungs. With a deep breath, the alveoli are stretched and their surface reaches 100-150 m2. The surface of the capillaries in the lungs is also large. There is also a sufficient difference in the partial pressure of the gases of the alveolar air and the tension of these gases in the venous blood.

From Table 15 it follows that the difference between the tension of gases in the venous blood and their partial pressure in the alveolar air is 110--40=70 mm Hg for oxygen, and 47--40=7 mm Hg for carbon dioxide. This pressure difference is sufficient to provide the body with oxygen and remove carbon dioxide from it.

The binding of oxygen to the blood. In the blood, oxygen combines with hemoglobin, forming an unstable compound - oxyhemoglobin. 1 g of hemoglobin is able to bind 1.34 cm3 of oxygen. The higher the partial pressure of oxygen, the more more oxyhemoglobin is formed. In the alveolar air, the partial pressure of oxygen is 100 - PO mm Hg. Art. Under these conditions, 97% of blood hemoglobin binds to oxygen.

In the form of oxyhemoglobin, oxygen is transported from the lungs by the blood to the tissues. Here, the partial pressure of oxygen is low and oxyhemoglobin dissociates, releasing oxygen. This ensures the supply of tissues with oxygen.

The presence of carbon dioxide in the air or tissues reduces the ability of hemoglobin to bind oxygen.

The binding of carbon dioxide to the blood. Carbon dioxide is carried in the blood in a chemically bound form - in the form of sodium bicarbonate and potassium bicarbonate. Part of it is transported by hemoglobin.

The binding of carbon dioxide and its release by the blood depend on its tension in the tissues and blood. An important role in this belongs to the enzyme carbonic anhydrase contained in erythrocytes. Carbonic anhydrase, depending on the content of carbon dioxide, accelerates the reaction many times over, the equation of which is: CO2 + H2O = H2CO3.

In tissue capillaries, where the tension of carbon dioxide is high, carbonic acid is formed. In the lungs, carbonic anhydrase promotes dehydration, which leads to the expulsion of carbon dioxide from the blood.

Gas exchange in the lungs in children is closely related to the peculiarities of the regulation of their acid-base balance. In children, the respiratory center is very sensitive to the slightest changes in the reaction of the blood. Even with a slight shift in balance towards acidification, shortness of breath occurs easily in children.

The diffusion capacity of the lungs in children increases with age. This is due to an increase in the total surface of the alveoli of the lungs.

The body's need for oxygen and the release of carbon dioxide are determined by the level of oxidative processes occurring in the body. With age, this level decreases, respectively, and the amount of gas exchange per 1 kg of weight decreases as the child grows.

REGULATION OF BREATH

Respiratory center. A person's breathing changes depending on the state of his body. It is calm, rare during sleep, frequent and deep during physical exertion, intermittent, uneven during emotions. When immersed in cold water a person’s breathing stops for a while, “it captures the spirit.” Russian physiologist N. A. Mislavsky in 1919 established that in the medulla oblongata there is a group of cells, the destruction of which leads to respiratory arrest. This was the beginning of the study of the respiratory center. The respiratory center is a complex formation and consists of an inhalation center and an exhalation center. Later it was possible to show that the respiratory center has a more complex structure and the overlying parts of the central nervous system also take part in the processes of regulation of respiration, which provide adaptive changes in the respiratory system to various activities of the body. An important role in the regulation of respiration belongs to the cerebral cortex.

The respiratory center is in a state of constant activity: impulses of excitation rhythmically arise in it. These impulses arise automatically. Even after the complete shutdown of the centripetal pathways leading to the respiratory center, rhythmic activity can be registered in it. The automatism of the respiratory center is associated with the process of metabolism in it. Rhythmic impulses are transmitted from the respiratory center along the centrifugal neurons to the respiratory muscles and diaphragm, providing an alternation of inhalation and exhalation.

reflex regulation. With pain irritation, with irritation of the abdominal organs, receptors of blood vessels, skin, respiratory tract receptors, a change in breathing occurs reflexively.

When ammonia vapor is inhaled, for example, the receptors of the mucous membrane of the nasopharynx are irritated, which leads to a reflex breath holding. This is an important protective device that prevents toxic and irritating substances from entering the lungs.

Of particular importance in the regulation of respiration are impulses coming from the receptors of the respiratory muscles and from the receptors of the lungs themselves. The depth of inhalation and exhalation depends on them to a greater extent. It happens like this. When you inhale, when the lungs are stretched, 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 descends, the diaphragm takes the form of a dome, the volume of the chest decreases and exhalation occurs. Exhalation, in turn, reflexively stimulates inspiration.

The cerebral cortex takes part in the regulation of respiration, which provides the finest adaptation of respiration to the needs of the body in connection with changes in environmental conditions and the life of the body.

Here are examples of the influence of the cerebral cortex on breathing. A person can hold his breath for a while, at will change the rhythm and depth of respiratory movements. The influence of the cerebral cortex explains the pre-start changes in breathing in athletes - a significant deepening and quickening of breathing before the start of the competition. It is possible to develop conditioned respiratory reflexes. If 5-7% carbon dioxide is added to the inhaled air, which in such a concentration speeds up breathing, and the breath is accompanied by the beat of a metronome or a bell, then after several combinations, only a bell or a beat of a metronome will cause an increase in breathing.

Humoral effects 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 causes irritation of the receptors in the blood vessels that carry blood to the head, and reflexively excites the respiratory center. Other acidic products that enter the blood act in a similar way, such as lactic acid, the content of which in the blood increases during muscular work.

The first breath of a newborn. During intrauterine development, the fetus receives oxygen and gives off carbon dioxide through the placenta to the mother's body. However, the fetus makes respiratory movements in the form of a slight expansion of the chest. In this case, the lungs do not straighten out, but only a slight negative pressure arises in the pleural space.

According to I. A. Arshavsky, this kind of fetal respiratory movements contribute to better blood flow and improve blood supply to the fetus, and are also a kind of training for lung function. During childbirth, after the umbilical cord is tied, the baby's body is separated from the mother's body. At the same time, carbon dioxide accumulates in the blood of the newborn and the oxygen content decreases. A change in the gas composition of the blood leads to an increase in the excitability of the respiratory center both humorally and reflexively through irritation of receptors in the walls of blood vessels. The cells of the respiratory center are irritated, and the first breath occurs in response. And then inhalation reflexively causes exhalation.

In the emergence of the first breath, an important role belongs to the change in the conditions of the newborn's existence in comparison with its intrauterine existence. Mechanical irritation of the skin when the obstetrician's hands touch the child's body, lower ambient temperature compared to intrauterine temperature, drying of the newborn's body in the air - all this also contributes to the reflex excitation of the respiratory center and the appearance of the first breath.

I. A. Arshavsky in the appearance of the first breath assigns the main role to the excitation of the spinal respiratory motor neurons, cells of the reticular formation of the medulla oblongata; the stimulating factor in this case is a decrease in the partial pressure of oxygen in the blood.

During the first breath, the lungs are straightened, which the fetus was in a collapsed state, the lung tissue of the fetus is very elastic, slightly stretchable. It takes a certain amount of force to stretch and expand the lungs. Therefore, the first breath is difficult and requires a lot of energy.

Features of the excitability of the respiratory center in children. 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 by the time of birth the functional formation of the respiratory center has not yet ended. This is evidenced by the large variability in the frequency, depth, rhythm of breathing in young children. The excitability of the respiratory center in newborns and infants is low.

Children of the first years of life are more resistant to lack of oxygen (hypoxia) than older children.

The formation of the functional activity of the respiratory center occurs with age. By the age of 11, the possibility of adapting breathing to various conditions of life is already well expressed.

The sensitivity of the respiratory center to the content of carbon dioxide increases with age and at school age reaches approximately the level of adults. It should be noted that during puberty there are temporary violations of the regulation of breathing and the body of adolescents is less resistant to oxygen deficiency than the body of an adult.

The functional state of the respiratory apparatus is also evidenced by the ability to arbitrarily change breathing (suppress respiratory movements or produce maximum ventilation). Voluntary regulation of breathing involves the cerebral cortex, centers associated with the perception of speech stimuli and responses to these stimuli.

Voluntary regulation of breathing is associated with the second signaling system and appears only with the development of speech.

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

Breathing during physical work. In an adult, during muscular work, pulmonary ventilation increases due to the increase and deepening of breathing. Activities such as running, swimming, skating, skiing, and cycling dramatically increase pulmonary ventilation. In trained people, the increase in pulmonary gas exchange occurs mainly due to an increase in the depth of breathing. Children, due to the peculiarities of their respiratory apparatus, cannot significantly change the depth of breathing during physical exertion, but increase their breathing. The already frequent and shallow breathing in children during physical exertion becomes even more frequent and superficial. This results in lower ventilation efficiency, especially in young children.

Adolescents, unlike adults, reach the maximum level of oxygen consumption faster, but also stop work faster due to the inability to maintain high oxygen consumption for a long time.

Proper breathing. Have you noticed that a person holds his breath for a short time when he listens to something? And why do rowers and hammerers have the moment of greatest gain coincides with a sharp exhalation (“wow”)?

In normal breathing, inhalation is shorter than exhalation. This rhythm of breathing facilitates physical and mental activity. It can be explained like this. During inhalation, the respiratory center is excited, while, according to the law of induction, the excitability of other parts of the brain decreases, and during exhalation, the opposite occurs. Therefore, the strength of muscle contraction decreases during inhalation and increases during exhalation. Therefore, performance decreases and fatigue sets in sooner if the inhalation is lengthened and the exhalation is shortened.

Teaching children to breathe correctly when walking, running and other activities is one of the tasks of the teacher. One of the conditions for proper breathing is taking care of the development of the chest. For this, the correct position of the body is important, especially while sitting at a desk, breathing exercises and other physical exercises that develop the muscles that move the chest. Especially useful in this regard are sports such as swimming, rowing, skating, skiing.

Usually a person with a well-developed chest will breathe evenly and correctly. It is necessary to teach children to walk and stand in a straight posture, as this contributes to the expansion of the chest, facilitates the activity of the lungs and provides 1 deeper breathing. When the body is bent, less air enters the body.

Adaptation of the body to physical activity

From a biological point of view, physical training is a process of directed adaptation of the body to training effects. The loads used in the process of physical training act as an irritant that stimulates adaptive changes in the body. The training effect is determined by the direction and magnitude of physiological and biochemical changes that occur under the influence of applied loads. The depth of the shifts occurring in the body depends on the main characteristics of physical activity:

* the intensity and duration of the exercises performed;

* the number of repetitions of exercises;

* the duration and nature of the rest intervals between repetitions of exercises.

A certain combination of the listed parameters of physical activity leads to the necessary changes in the body, to the restructuring of metabolism and, ultimately, to an increase in fitness.

The process of adaptation of the body to the effects of physical activity has a phase character. Therefore, two stages of adaptation are distinguished: urgent and long-term (chronic).

The stage of urgent adaptation is mainly reduced to changes in energy metabolism and related functions of vegetative support based on the already formed mechanisms for their implementation, and is a direct response of the body to single effects of physical activity.

With repeated repetition of physical impacts and the summation of many traces of loads, long-term adaptation gradually develops. This stage is associated with the formation of functional and structural changes in the body that occur as a result of stimulation of the genetic apparatus of cells loaded during work. In the process of long-term adaptation to physical activity, the synthesis of nucleic acids and specific proteins is activated, resulting in an increase in the capabilities of the musculoskeletal system, and its energy supply is improved.

The phase nature of the processes of adaptation to physical loads allows us to distinguish three types of effects in response to the work performed.

An urgent training effect that occurs directly during exercise and during an urgent recovery period within 0.5 - 1.0 hours after the end of work. At this time, the oxygen debt formed during work is eliminated.

Delayed training effect, the essence of which is the activation of plastic processes by physical exercise for excessive synthesis of cellular structures destroyed during work and replenishment of the body's energy resources. This effect is observed in the late phases of recovery (usually up to 48 hours after the end of the load).

The cumulative training effect is the result of the sequential summation of the urgent and delayed effects of repetitive loads. As a result of the cumulation of trace processes of physical influences over long periods of training (more than one month), there is an increase in performance indicators and an improvement in sports results.

Small physical loads do not stimulate the development of the trained function and are considered ineffective. To achieve a pronounced cumulative training effect, it is necessary to perform an amount of work that exceeds the value of ineffective loads.

A further increase in the volume of work performed is accompanied, to a certain limit, by a proportional increase in the trained function. If the load exceeds the maximum allowable level, then a state of overtraining develops, and adaptation fails.

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The regulation of respiration is carried out by the central nervous system, special areas of which determine automatic respiration - alternating inhalation and exhalation and arbitrary breathing, which provides adaptive changes in the respiratory system, corresponding to a specific external situation and ongoing activities. The group of nerve cells responsible for the implementation of the respiratory nicla is called respiratory center.

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. The 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 carbon dioxide concentration, and mechanoreceptors lungs and respiratory muscles. Airway receptors also influence the regulation of respiration. 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 depend to a greater extent on them.

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 and blood causes irritation of the receptors in the blood vessels that carry blood to the head, and reflexively excites the respiratory center. Other acidic products that enter the blood act in a similar way, such as lactic acid, the content of which in the blood increases during muscular work.

Features of the regulation of respiration in childhood. By the time of birth, the functional formation of the respiratory center has not yet ended. This is evidenced by the large variability in the frequency, depth, rhythm of breathing in young children. The excitability of the respiratory center in newborns and infants is low. Children of the first years of life are more resistant to lack of oxygen (hypoxia) than older children.

The formation of the functional activity of the respiratory center occurs with age. By the age of 2, the possibility of adapting breathing to various conditions of life is already well expressed.

The sensitivity of the respiratory center to the content of carbon dioxide increases with age and at school age reaches approximately the level of adults. During puberty, temporary violations of the regulation of breathing occur and the body of adolescents is less resistant to oxygen deficiency than the body of an adult.

One of the important factors in ensuring the 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.

One of the conditions for proper breathing is taking care of the development of the chest. For this it is important:

the correct position of the body in the process of various activities,

· breathing exercises,

· class exercise developing the chest.

Question 3. Hygienic value of indoor air

Staying in a dusty, poorly ventilated room is the cause of not only the deterioration of the functional state of the body, but also many diseases. A person is favorably affected by light and negative ions, and their number in the working premises is gradually decreasing. The beneficial physiological effect of negative air ions was the basis for the use of artificial ionization of indoor air. In parallel with the deterioration of the ionic composition, an increase in temperature and humidity in the premises, the concentration of carbon dioxide increases, ammonia and various organic substances accumulate. The deterioration of the physical and chemical properties of the air, especially in rooms with a reduced height, entails a significant deterioration in the performance of the cells of the human cerebral cortex.

Microclimate. Temperature, humidity and air velocity (cooling force) in the classroom characterize its microclimate. In connection with the increase in the temperature of the outdoor air and the air in the room, a decrease in efficiency was noticed. In rooms with a relative humidity of 40-60% and an air velocity of no more than 0.2 m / s, its temperatures are normalized in accordance with the climatic regions. The difference in air temperature in the room both vertically and horizontally is set within 2-3°C.

AGE FEATURES OF THE DIGESTIVE ORGANS. METABOLISM AND ENERGY.

FOOD HYGIENE.

1. The structure and functions of the digestive organs.

2. Protective food reflexes. Prevention of gastrointestinal diseases.

3. Metabolism and energy.

4. Metabolism of proteins, fats and carbohydrates, age-related features.

5. Hygienic requirements for catering.

Question 1. The meaning, structure and functions of the digestive organs

For the normal functioning of the body, its growth and development, a regular intake of food containing complex organic substances (proteins, fats, carbohydrates), mineral salts, vitamins and water is necessary. All these substances are necessary to meet the body's need for energy, for the implementation of biochemical processes occurring in all organs and tissues. Organic compounds are also used as a building material in the process of body growth and reproduction of new cells to replace dying ones. Main nutrients in the form in which they are in food, they cannot be used by the body, but must be subjected to special processing - digestion.

Digestion called the process of physical and chemical processing of food and turning it into simpler and more soluble compounds that can be absorbed, carried by the blood, absorbed by the body.

Physical processing consists in grinding food, rubbing it, dissolving it. Chemical changes are complex reactions that take place in various departments digestive system, where, under the influence of enzymes contained in the secrets of the digestive glands, complex insoluble organic compounds contained in food are broken down, turning them into soluble and easily absorbed substances by the body. Enzymes- These are biological catalysts produced by the body and differ in a certain specificity.

In each of the departments digestive system there are specialized food processing operations associated with the presence of specific enzymes in each of them.

The food mass is processed by the juice of the two main digestive glands - liver and pancreas and juice of small intestinal glands. Under the influence of the enzymes contained in them, the most intensive chemical processing of proteins, fats and carbohydrates occurs, which, undergoing further splitting, are brought in the duodenum to such a state that they can be absorbed and assimilated by the body.

The main function of the small intestine is absorption. Enzymatic processing of food in the colon is very small. Numerous bacteria live in the large intestine. Some of them break down plant fiber, since there are no enzymes in human digestive juices to digest it. Absorption is a complex physiological process that occurs mainly due to the active work of intestinal epithelial cells.

Children are characterized by increased permeability of the intestinal wall; in a small amount, natural milk proteins and egg white are absorbed from the intestines. Excessive intake of unsplit proteins in the child's body leads to various kinds of skin rashes, itching and other adverse effects. Due to the fact that the permeability of the intestinal wall in children is increased, foreign substances and intestinal poisons formed during the decay of food, products of incomplete digestion can enter the blood from the intestines, causing various kinds of toxicosis.

An important function of the intestine is its motility- is carried out by the longitudinal and annular muscles of the intestine, the contractions of which cause two types of intestinal movements - segmentation and peristalsis. Due to the motor activity of the intestine, the food gruel is mixed with digestive juices, it moves through the intestine, as well as an increase in intra-intestinal pressure, which contributes to the absorption of some components from the intestinal cavity into the blood and lymph. Peristaltic movements propagate in slow waves (1-2 cm / s) along the intestine in the direction from the oral cavity and contribute to pushing food.