Ministry of Public Education of the Republic of Uzbekistan Navoi State Pedagogical Institute Department: Fundamentals of Medical Knowledge. Regulation of respiration and its age-related features Age-related features of the mechanism of respiration regulation

cardiac activity and vascular tone

In newborns, heterometric myogenic mechanisms of regulation are weakly manifested. Homeometrics are well expressed. At birth, there is a normal innervation of the heart. When the parasympathetic nerves are stimulated, the cardiac activity of the newborn may be inhibited, but their effect on the heart is weaker than in adults. Newborns also have a pronounced Danini-Ashner reflex, which indicates the presence of reflex mechanisms of inhibition of the heart. However, the tone of the vagus centers is very little expressed. As a result, newborns and young children have a high heart rate. After birth, the tonic effects of the sympathetic nerves on the heart are also very weak. In the neonatal period, reflexes from the baroreceptors of the carotid sinus zones are also included. The development of the nervous mechanisms of regulation of the heart is generally completed by the age of 7-8 years. However, during this period, cardiac reflexes remain labile: they quickly arise and stop.

Myogenic mechanisms of regulation of vascular tone are active already in the period of intrauterine development. The smooth muscles of the vessels respond to changes in the reaction of the blood, the tension of oxygen in the blood. The innervation of blood vessels occurs in the early stages of intrauterine development. During the neonatal period, tonic nerve impulses enter the vessels along the sympathetic nerves, narrowing them. Functioning pressor reflexes from the carotid sinus zones. But there are no depressor reflexes from these zones. This is one of the reasons for the instability blood pressure. The formation of depressor reflexes to an increase in blood pressure begins from 7-8 months of age. From the newborn, reflexes from the chemoreceptors of the vessels are also included. Therefore, there are vascular reactions to hypercapnia, which are still little expressed. In newborns great importance the renin-angiotensin system has a role in maintaining blood pressure.

^ Age features functions of external respiration

The structure of the respiratory tract of children differs markedly from the respiratory organs of an adult. In the first days of postnatal ontogenesis, nasal breathing is difficult, since the child is born with an underdeveloped nasal cavity. It has relatively narrow nasal passages, with practically no paranasal sinuses and inferior nasal passage. The dead space volume is 4-6 ml. Only from the age of 2 do the maxillary sinuses increase. The frontals are fully formed by the age of 15. The larynx of children is relatively narrower than that of adults and grows slowly until the age of 5. The most intensive growth of the larynx occurs at 10-14 years. Fully the formation of the larynx is completed by the end of puberty. The mucosa of the child's upper respiratory tract is thin, dry, and easily vulnerable. This contributes to the occurrence of its inflammatory diseases. The growth of the lungs occurs due to the differentiation of the bronchial tree and an increase in the number and volume of the alveoli. This provides an increase in gas exchange. In early childhood, children have an abdominal type of breathing. By the age of 7, there is a transition to the chest type. Finally, the type of breathing is formed in adolescence. Girls have chest, boys have abdominal. In newborns, the force of respiratory movements is 30-70 per minute. At 5-7 years old 25 per minute. At 13-15 years old 18-20 per minute. A higher respiratory rate ensures good ventilation of the lungs. The vital capacity of the lungs of a newborn is 120-150 ml. It grows most intensively at the age of 9-10 years. During puberty, VC in boys becomes greater than in girls. Tidal volume and minute respiratory volume in newborns are 16 and 720 ml, respectively, at 5-7 years old 156 and 3900 ml, at 13-15 years old 360 and 6800 ml. The most strongly minute ventilation increases in 10-13 years.

^ Gas exchange in lungs and tissues, transport of gases by blood

On the first day after birth, ventilation increases and the diffusion surface of the lungs grows. Due to the high rate of ventilation of the alveoli in the alveolar air of newborns, there is more oxygen (17%) and less carbon dioxide (3.2%) than in adults. Accordingly, the partial pressure of oxygen is higher (120 mm Hg) and lower than carbon dioxide (23 mm Hg). As a result of intensive ventilation in combination with relatively low perfusion of the lungs with blood, there is no equalization of partial pressures and tensions of respiratory gases in the alveolar air and blood. Therefore, the tension of oxygen in the blood of a newborn is 70-90 mm Hg, and that of carbon dioxide is 35 mm Hg. There is mild hypoxemia and hypocapnia. Before the first breath, the blood contains 40-80% oxyhemoglobin, in the first few days its content increases to 87-97%. The saturation of the blood with oxygen is facilitated by the content of fetal hemoglobin and the low content of 2,3-diphosphoglycerate. A good supply of tissues with oxygen contributes to the large oxygen capacity of the blood of newborns. Oxygen consumption is greatest in the first minutes after birth. But after an hour it is reduced by half. With age, the partial pressure of oxygen in the alveolar air decreases, while that of carbon dioxide increases. The tension of carbon dioxide in your blood remains lower and oxygen higher until the age of 15-17 years. After 30-45 days in erythrocytes, fetal hemoglobin is completely replaced by hemoglobin A. Therefore, the oxyhemoglobin dissociation curve from this moment differs little from the curve of an adult.

^ Features of the regulation of breathing

The functions of the bulbar respiratory center are formed during fetal development. Premature babies born at 6-7 months are capable of independent breathing. Respiratory periodic movements in newborns are irregular: more frequent breathing is replaced by a rarer one. Sometimes there are breath holdings on exhalation lasting up to several seconds. Preterm infants may experience Cheyne-Stokes breathing. These respiratory rhythm disturbances most often occur during sleep. The respiratory center of newborns has a high resistance to lack of oxygen. Due to this, they can survive in conditions of sufficiently long, lethal for adults, hypoxia. Vagus nerves from the early stages of extrauterine development play a leading role in the coordination of breathing. Chemoreceptors of vascular reflexogenic zones are also involved in the process of respiration regulation from the first minutes of life. At the same time, the sensitivity of these receptors to the level of carbon dioxide is low. The main role is played by central chemoreceptors. Low, but physiological reactivity of the newborn organism to hypercapnia has importance. With a decrease in sensitivity to CO 2, prolonged apnea can be observed, which is the cause of sudden death in children.

Newborns also have respiratory reflexes from the proprioreceptors of the respiratory muscles. They provide an increase in their contractions with increasing resistance to breathing.

With age, the activity of the respiratory center improves. Stable respiratory reflexes develop, the role of the pneumotaxic center increases. During the first year, the ability to voluntarily regulate breathing develops. By the age of 7, the main conditioned reflex mechanisms of breathing are established.

^ General patterns of nutrition development in ontogenesis

In ontogeny, there is a gradual change in types of nutrition. The first stage is histotrophic nutrition due to the reserves of the egg, yolk sac and uterine mucosa. From the moment the placenta is formed, the hemotrophic stage begins, at which nutrients come from the mother's blood. From 4-5 months of intrauterine development, amniotrophic nutrition is connected to hemotrophic nutrition. It consists in the entry of amniotic fluid into the digestive tract of the fetus, where the nutrients contained in it are digested, and the products of digestion enter the blood of the fetus. By the end of pregnancy, the amount of fluid absorbed approaches a liter. After birth, the lactotrophic period of breastfeeding begins. In the first 2 days after childbirth, the mammary glands produce colostrum. It is high in protein and relatively low in carbohydrates and fats. The nutrients contained in it are easily digested and absorbed by the body of the newborn. This period lasts up to 5-6 months. From this point on, the nutrients supplied with milk become insufficient. Therefore, there is a transition to mixed feeding. The beginning of complementary feeding occurs at the time of the formation of mechanisms for the digestion of non-dairy foods. The inclusion of complementary foods in the diet stimulates the development of the digestive system and its adaptation to the subsequent definitive nutrition. After the final maturation of the digestive cycle, there is a transition to definitive nutrition.

^ Features of the functions of the digestive organs in infancy

After birth, the first digestive reflex is activated - sucking. It is formed in ontogeny very early at 21-24 weeks of fetal development. Sucking begins as a result of irritation of the mechanoreceptors of the lips. With lactotrophic nutrition, digestion is carried out through autolytic and own. Autolytic is carried out by milk enzymes. Own enzymes of the alimentary canal. Salivary glands newborns secrete little saliva and it practically does not participate in the hydrolysis of components mother's milk. In newborns, the stomach has a rounded shape. Its capacity is 5-10 ml. In the first weeks it increases by 30 ml, by the end of the first year up to 300 ml. The stomach of a newly born baby contains a large number of amniotic fluid. The reaction of the contents is slightly alkaline. Within 12 hours, its pH drops to 1.0, and then rises again to 4.0-6.0 by the end of the first week. In the future, the pH decreases again and in children of 1 year is 3.0-4.0. The intensity of secretion of gastric enzymes in children of 1 year is lower than in adults. The activity of enzymes is directed to the hydrolysis of casein. The ability to split vegetable proteins is acquired for 3 months, meat proteins for 6 months. For the first 2 months, fetal pepsin is secreted, which serves to curdle milk. All pepsins have maximum activity at pH 3.0-4.0. In the gastric juice there is a gastric lipase that breaks down milk fats. The intestines of children, relative to the length of the body, has a large extent. The mucosa is thinner and contains fewer villi. There are fewer smooth muscle cells in the wall. The pancreas of a newborn weighs 2-4 g. But it rapidly increases and by the end of the year its weight is 10-12 g. Initially, secretory activity is low, but by the end of the first month, the production of trypsinogen and procarboxypeptidases increases. In the second year, the secretion of amylase and lipase increases. The bile of infants contains less bile acids and cholesterol, but more bile pigments and mucin. The activity of enzymes in the small intestine is high. The juice contains all peptidases, carbohydrases and lipases. A special role is played by lactase, which breaks down milk sugar. In the first year, parietal digestion is dominant, the role of abdominal digestion is insignificant.

^ Functions of the digestive organs in definitive nutrition

With the transition to definitive nutrition, the secretory and motor activity of the digestive canal of the child is gradually approaching the indicators of adulthood. The use of predominantly dense foods requires improved mechanical processing of food. The teething process begins. At the age of 6-12 months, the incisors erupt. From 12 to 16 months the first molars. At 16-20 months. fangs. At 20-30 months. second molars. The eruption of permanent teeth begins at 5-6 years of age and generally ends at 12-13 years of age. Completely the formation of the dentoalveolar system ends with the eruption of "wisdom teeth" at the age of 18-25. With an increase in the number of teeth, the chewing cycle becomes more coordinated. Chewing movements adapt to the type of food. Saliva secretion increases up to 10 years. The amount of amylase in it is up to 3-4 years. As they grow older, the volume of secreted gastric juice and the content of hydrochloric acid and pepsinogens in it increase. Digestion in the small intestine also gradually adapts to new conditions. The weight of the pancreas increases and at the age of 15 its weight is about 50 g. The volume of pancreatic juice increases. At the age of 4-6, the content of proteases in it reaches its optimum, and at 6-9, amylase and lipase. The amount of bile produced by the liver also increases. In bile, the content of bile acids increases, which improves the absorption of fats. The volume of intestinal juice and the activity of its enzymes also increase. The role of abdominal digestion is increasing.

In a newborn, the gastrointestinal tract is sterile. But obligate microflora is necessary for normal digestion. Therefore, on the 2-4th day, the colonization of the intestine by microorganisms begins. Over the next two weeks, the composition of the microflora stabilizes. The transition to definitive nutrition changes the microflora. Bifidobacteria, E. coli, enterococci begin to dominate.

^ Metabolism and energy in childhood

The intake of nutrients in the child's body on the first day does not cover his energy costs. Therefore, glycogen stores in the liver and muscles are used. Its quantity in them is rapidly decreasing. Restoration of its reserves occurs within 2-3 weeks. The concentration of glucose in the blood of a newborn is 4.1 mmol / l. But already in the first hours it decreases to 2.9 mmol / l and comes to the initial level by the end of the first week. Due to the rapid depletion of glycogen stores, fats become the main source of energy. The intensity of their decay decreases to 6-12 months. The necessary glucose is produced by glycogenolysis and gluconeogenesis. Therefore, at birth, the respiratory coefficient is about 1.0. After 12 hours 0.75. By the fifth day 0.85. Plastic needs are provided by proteins and fats. The protein requirement of a 3-month-old baby is about 2.5 g per kg of body weight per day. At 5 months 3.0 g. 3.5 g per year. At 3 years old, 4 g. Then it steadily decreases and at 17 years old, 1.5 g of protein per kg of body weight per day is required. The need for fats is maximum in the first 6 months. life. The greatest need for carbohydrates at 1-3 years. The basal metabolic rate increases as the child grows. On the first day, its value averages 122 kcal. By the end of the first month 205 kcal. For 6 months 445 kcal. At 1 year 580 kcal. At 5 years old 840 kcal. At 14 years old, 1360 kcal. In general, the value of basal metabolism per kg of body weight in a child is greater than in adults. This is due to the high intensity of metabolic processes in their body. The older the children, the greater the work increase. First of all, it goes to maintaining body posture and movement. In the neonatal period, it makes up only 9% of the total energy exchange. By the year it increases to 23%, and by the age of 14 to 43%. How less baby, the weaker the specific-dynamic effect of food. For example, in newborns, proteins cause an increase in energy costs of only 15%.

^ Development of thermoregulation mechanisms

In a born child, the rectal temperature is higher than that of the mother and is 37.7-38.2 0 C. After 2-4 hours, it drops to 35 0 C. If the decrease is greater, this is one of the signs of the poor condition of the newborn. By the end of the first day, it again increases to 36-37 0 C. During the next day, temperature fluctuations are noted. A stable temperature is set for 5-8 days. The body temperature of newborns, due to the immaturity of thermoregulation mechanisms, is very dependent on temperature. environment. Therefore, the child must be protected from cooling, since hypothermia quickly develops without previous signs. In some newborns, transient fever may occur on days 2-3 - an increase in temperature to 39-40 0 C. It is explained by irritation of heat-producing centers with a lack of water in the body. There are no daily temperature fluctuations on the first day. They appear only at 4 weeks. Heat transfer in children occurs more intensively than in adults. This is due to the larger body surface to its weight, intensive skin circulation, more active evaporation of water from the surface of the body. There is no shivering thermogenesis in newborns. The increase in heat production is provided mainly by brown fat, which is present not only between the shoulder blades, but also under the skin of various areas of the body. In general, the thermoregulation of a newborn is much less perfect than in adulthood. However, peripheral and central thermoreceptors, the thermoregulation center of the hypothalamus, are actively functioning. With age, thermoregulatory mechanisms improve. The efficiency of sweating increases, the ability to trembling thermogenesis appears, the importance of reflex mechanisms for maintaining temperature homeostasis increases. By the age of 15-16, the mechanisms of thermoregulation basically correspond to a mature organism.

^ Age features of kidney function

Morphologically, the maturation of the kidneys ends by 5-7 years. Kidney growth continues until the age of 16. The kidneys of children up to 6-7 months in many ways resemble the embryonic kidney. At the same time, the weight of the kidneys (1:100) is relatively greater than in adults (1:200). The pore sizes of the basement membrane in children are 2 times smaller than in adults, and the rate of renal blood flow is relatively lower. Therefore, the rate of glomerular ultrafiltration is lower. But it grows rapidly during the first year. Even less mature is the tubular apparatus. The length of the tubules is much less. Therefore, the rate of reabsorption is lower. But at the same time, glucose is completely reabsorbed. Water and ions are less intensively reabsorbed in the proximal tubules. But in the distal this process is much more active. The intensity of secretion processes is also low. The concentration of sodium and chlorine in the final urine up to 6 months. low. Even by 18 months, their content is significantly lower than in adults. Sodium retention in the body leads to increased water reabsorption and a tendency to edema. The weak concentration ability of the kidneys of children is explained by the immaturity of the rotary-countercurrent mechanism.

^ Improving unconditionally - reflex activity

child's brain.

In postnatal ontogenesis, unconditional reflex functions are improved. Compared with an adult, newborns have much more pronounced processes of irradiation of excitation, therefore, when performing coordinated movements, such as sucking, they have a large number of additional movements (arms, legs, torso, etc.). A newborn and an infant almost never, except for sleep, is motionless even in sleep. It moves in about 5 minutes. His movements are erratic and uncoordinated. Crying, sneezing, coughing are also accompanied by reflex movements. Cry and defensive movements of the body, arms, legs with painful stimuli are present already on the 1st day after birth. Sucking is one of the first coordinated movements. In newborns, the following motor reflexes are detected: tonic hand reflex (grasping an object when it touches the skin of the palms), crawling reflex, spinal reflex (arching the back when stroking the skin

Between the shoulder blades), etc.

Newborns already have ocular reflexes: pupillary, corneal. As well as swallowing, knee, Achilles, and other unconditioned reflexes that persist throughout life. However, they have a positive Babinski reflex. Subsequently, due to the formation of conditioned reflexes, complex motor skills are developed, for example, walking, finger movements, etc.

In the first days of life, an external stimulus does not cause changes in behavior. However, in the future, with the appearance of stimuli previously unknown to the child, exploratory-orienting unconditioned reflexes arise. The simplest unconditional exploratory reflexes are formed by the end of the 1st beginning of the 2nd week. Their significance lies in the fact that they contribute to the emergence of conditioned research reflexes.

^ Higher nervous activity of the child.

A child is born with a relatively small number of inherited unconditioned reflexes, mainly of a protective and nutritional nature. However, after birth, he finds himself in a new environment and these reflexes cannot ensure his existence in it. By the time of birth, the child's brain does not complete its development, but is already capable of forming conditioned reflex connections. As established, the first conditioned reflexes can be formed as early as 5-7 days on the basis of food unconditioned reflexes.

On the 15th day, it is possible to develop a conditioned reflex to the position of the body, i.e. sucking reflex in the supine position. The formation of temporary bonds during this period is slow, they are unstable. At 3 - 4 months of life, it is already possible to develop extinction and differential inhibition. However, completely internal inhibition is fixed only by the 5th month. At the same time, all the main mechanisms that provide V.N.D. By this period, conditioned reflexes to sound stimuli are most easily formed, more difficult to visual and tactile.

For children preschool age live orienting reactions are characteristic. In the last months of the first and the entire second year of life, the formation of speech occurs. Speech in children is formed by imitation according to the laws of the development of conditioned reflexes. Lexicon grows rapidly during the 2nd - 3rd year of life. The period up to 3 years is optimal for the formation of speech. Up to 3 - 5 years, conditioned reflexes are hardened with difficulty, because. the child quickly develops protective inhibition, up to falling asleep. At the age of 5-6, the strength and mobility of nervous processes increase. Children 6 years old can already concentrate for 15 - 20 minutes. Improves internal inhibition, thereby facilitating the differentiation of stimuli. In 5 - 6 years, inner speech appears. From the age of 6, abstract thinking begins to form.

In children 7-9 years old, the formation of conditioned reflex connections is accelerated and they become stronger. Protective braking develops at a much higher load. Better is the formation of complex conditioned reflexes and conditioned reflexes of higher orders. Conditioned reflexes are easily extinguished due to internal inhibition. At the age of 12-16, excitation processes in the cortex and subcortex predominate. Excitation is often spilled. Therefore, in adolescents, generalized motor reactions are observed during psycho-emotional arousal (facial expressions, movements of the limbs, etc.). Differentiation processes worsen again. Concentration of attention becomes difficult, phenomena of mental instability appear - a rapid transition from joy to depression and vice versa. The coordinating, controlling role of the second signaling system is reduced. All these phenomena decrease by the age of 17.

Respiration is controlled by the central nervous system, whose special areas determine automatic respiration - alternating inhalation and exhalation and arbitrary breathing, providing 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. Others operate in a similar way. sour foods, entering the blood, for example, 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 in school age reaches about 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 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.

One of the conditions correct breathing is about development chest. For this it is important:

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

· breathing exercises,

Physical exercises that develop 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. Essential nutrients in the form in which they are found in food 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, occurring in various parts of the digestive system, where, under the influence of enzymes contained in the secrets of the digestive glands, the breakdown of complex insoluble organic compounds contained in food, turning them into soluble and easily absorbed by the body substances. Enzymes- These are biological catalysts produced by the body and differ in a certain specificity.

In each of the sections of the digestive system, specialized food processing operations occur, 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 absorbed 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 bloodstream from the intestines, causing all sorts of toxicosis.

important function bowel is his 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.

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 breathing, providing the finest adaptation of breathing to the needs of the body in connection with changes in conditions. external environment and life of the organism. 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 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 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 at a high level for a long time.
Voluntary changes in breathing play an important role in the execution of a series breathing exercises and help to correctly combine certain movements with the phase of breathing (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 performance exercise much attention is paid to 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 expiration, the diaphragm rises, which increases the outflow of 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 physicochemical characteristics 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 in indoor areas 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 temperature and humidity in the 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 under 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 clean air provided by the device of the 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 device of central exhaust ventilation with wide aeration - inflow atmospheric air.
The opening part of the windows (transoms, vents) in each room in its own way 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 flows 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 negative outside temperatures, the temperature in the classrooms already 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.
Heat in classes (up to 26 °) leads to the tension of thermoregulatory processes and a decrease in efficiency. In such conditions, the mental performance of students by the end of the lessons is sharply reduced. The influence of temperature conditions on the performance of students during classes is even more clearly manifested. physical education and labor.
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 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, gaps between the first row of desks and windows in winter time 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, a 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 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 water heating system is used low pressure. 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.

Chapter XII Age features of the excretory organs.
Personal hygiene. Hygiene of clothes and shoes

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

The value of the 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, organic substances, their increased activity is observed with intense muscular work and an increase in ambient temperature.
The main role in the excretory processes belongs to the kidneys, which remove water, salts, ammonia, urea, 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 medicines are removed through the kidneys.
The kidneys maintain a certain constant blood reaction. With the accumulation of acidic or alkaline metabolic products in the blood through the kidneys, the excretion of excess salts increases. In maintaining the constancy of the reaction of the blood, the ability of the kidneys to synthesize ammonia, which binds acidic products, plays a very important role.

Despite the fact that respiratory movements are performed starting from the early stages of ontogenesis in the fetus, the structures of the respiratory center are morphologically and functionally not fully formed.

The respiratory movements of the fetus are mainly regulated by the part of the respiratory center located in the medulla oblongata, and the influence of the higher parts of the respiratory center in the regulation of breathing at this stage is not significant. Cortical (voluntary) regulation of respiration occurs together with speech.

The respiratory center of the fetus, newborns and infants has low excitability, although already in the antenatal period, its neurons have automatism, which helps to maintain lung ventilation in the newborn. The respiratory center has a high reactivity to impulses from lung stretch receptors, but a low ability to respond to irritation of central and peripheral chemoreceptors that are sensitive to pH and CO 2 concentration in the blood (the latter begin to function from the 1st month of life). Due to the functional immaturity of the respiratory center, the rhythm of breathing is irregular. The activity of the respiratory center is well coordinated with the centers of sucking and swallowing: during feeding, the frequency of breathing coincides with the frequency of sucking movements (the sucking center usually imposes its higher frequency of excitation on the respiratory center). During swallowing, the airways overlap and are separated from the pharynx by the soft palate and epiglottis, and the vocal cords close.

With age, the excitability of the respiratory center gradually increases and at school age becomes the same as in adults. In young children, voluntary regulated breathing is poorly developed, so they cannot hold their breath for a long time while singing or reading poetry. The role of cortical control in voluntary regulation of respiration increases in connection with the development of speech function.

During puberty, there is an increase in the excitability of the respiratory center, in connection with which there is a deterioration in the coordination of inhalation and exhalation. In this period, with a slight decrease in the amount of 0 2 in the inhaled air, hypoxemia often occurs (oxygen starvation).

In the fetus, the regulation of respiratory movements is carried out mainly by the content of 0 2 in the blood. With a decrease in the content of 0 2 in the blood of the fetus, the frequency and depth of respiratory movements increase. At the same time, heart rate increases, blood pressure rises, and blood circulation speed increases. However, the mechanism of such adaptation to hypoxemia in the fetus is different than in adults.

First, the reaction in the fetus is not of a reflex (from the chemoreceptors of the aortic arch and carotid sinus, as in an adult), but of a central origin, and persists after the chemoreceptors are turned off.

Secondly, the reaction is not accompanied by an increase in oxygen capacity and the number of red blood cells in the blood, which occurs in an adult.

The respiration of the fetus is negatively affected not only by a decrease, but also by an increase in the content of 0 2 in the blood. With an increase in the content of 0 2 in the mother's blood (for example, when pure 0 2 is inhaled), the respiratory movements of the fetus stop. At the same time, the heart rate decreases.

In a newborn, the regulation of breathing is carried out mainly by the nerve centers of the medulla oblongata.

From the first days of extrauterine life, the vagus nerves play an important role in the regulation of respiration.

In children of the first years of life, there is a higher resistance to oxygen starvation. This is explained:

1) lower excitability of the respiratory center;
2) a higher content of 0 2 in the alveolar air, which allows you to maintain its normal tension in the blood for more long time;
3) the specificity of redox reactions in the early periods of life, which allows for a long time to maintain the metabolism at a sufficient level under anaerobic conditions.

The chemoreceptors of the reflexogenic zones of the CCC begin to function even before birth. They respond to a relatively small decrease in the 0 2 voltage and an increase in the CO 2 voltage. In contrast to the reaction of adults, in newborns, changes in lung ventilation to a decrease in voltage 0 2 are of a short and unstable nature. With age, the ventilation response to a decrease in voltage 0 2 becomes more persistent and pronounced. However, with the same reduction partial pressure 0 2 in the inhaled air in children and adolescents, the MOD increases less than in adults. At the same time, the ventilatory response to inhalation of CO 2 in newborns is more pronounced than in adults.

In children on physical activity an increase in lung ventilation is achieved mainly due to an increase in the respiratory rate, while in an adult it is due to a deepening of breathing. With frequent and shallow breathing, air is exchanged mainly in the airways, and alveolar air under these conditions is exchanged insignificantly. Hence, in children, the efficiency of pulmonary ventilation is lower than in adults, which even in trained children cannot ensure proper gas exchange of the body when intensive work. In addition, the coefficient of oxygen assimilation by tissues in children is significantly lower than in adults, which leads to a greater increase in the work of the cardiovascular system to provide tissues with sufficient 0 2 . The efficiency and economy of oxygen supply to the body increases and reaches the level of adults by the age of 20 (in adolescence these indicators are declining, the quality of their regulation is deteriorating).

The impact on breathing of drugs and various toxic substances is stronger, the younger the child.

Ministry of Public Education of the Republic of Uzbekistan Navoi State Pedagogical Institute Department: Fundamentals of Medical Knowledge. Regulation of respiration and its age-related features Age-related features of the mechanism of respiration regulation

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Ministry of Public Education of the Republic of Uzbekistan Navoi State Pedagogical Institute Department: Fundamentals of Medical Knowledge. Regulation of respiration and its age-related features Age-related features of the mechanism of respiration regulation

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