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Lecture notes, cheat sheets
Age-related anatomy and physiology. Patterns of growth and development of the child’s body (the most important)
Directory / Lecture notes, cheat sheets Table of contents (expand) Topic 1. PATTERNS OF GROWTH AND DEVELOPMENT OF CHILDREN'S ORGANISM 1.1. Basic patterns of growth and development The general biological properties of living matter are the processes of growth and development, which begin from the moment of fertilization of the egg and represent a continuous progressive process that takes place throughout life. The organism develops in leaps and bounds, and the difference between the individual stages of life is reduced to quantitative and qualitative changes. Growth is an increase in the size and volume of a developing organism due to the reproduction of body cells and an increase in the mass of living matter. The changes relate primarily to anthropometric indicators. In some organs (such as bones, lungs), growth is carried out mainly due to an increase in the number of cells, in others (muscles, nervous tissue), the processes of increasing the size of the cells themselves predominate. It must be said that this definition of height does not affect changes due to fat deposition or water retention. Absolute indicators of body growth are an increase in the total amount of protein in it and an increase in the size of bones. General growth is characterized by an increase in body length, depending on the growth and development of the skeleton, which, in turn, is one of the main indicators of the health and physical development of the child. Growth and physical development occur simultaneously. In this case, there is a complication of the structure, which is called the morphological differentiation of tissues, organs and their systems; the shape of the organs and the whole organism changes; functions and behavior are improved and complicated. There is a mutual natural dependence between growth and development. During this process, quantitative changes accumulate, which leads to the emergence of new qualities. It is impossible to consider the presence of age-related features in the structure or activity of various physiological systems as evidence of the inferiority of the child's body at individual age stages, because each age is characterized by a complex of such features. The relationship between the physical and mental development of children. Famous teacher and anatomist P.F. Lesgaft put forward a position on the relationship between the physical and mental development of children: physical education is carried out by influencing the psyche of children, which, in turn, affects the development of the psyche. In other words, physical development determines mental development. This is especially clearly detected in congenital underdevelopment of the cerebral hemispheres, which manifests itself in dementia. Children who have such a defect from birth cannot be taught to speak and walk; they lack normal sensations and thinking. Or another example: after removal of the gonads and with insufficient function of the thyroid gland, mental retardation is observed. It has been established that mental performance increases after physical education lessons, a small set of physical exercises in general education lessons and before homework. Speech and physical and mental development of children. The role of speech for the physical and mental development of children cannot be overestimated, since the speech function has a leading influence on their emotional, intellectual and physical development. At the same time, the role of speech in the formation of the student’s personality and consciousness, as well as in his learning to work and physical exercises, increases. With the help of speech, thoughts are formed and expressed; through speech, children are taught and raised. As children grow and develop, their ability to reflect objective reality in concepts, abstractions and generalizations, in the laws of nature and society increases. Initially, concrete, visual-figurative and practical-effective thinking predominates in primary school age. Specific images and actions develop a specific memory in younger students, which, in turn, has a significant impact on their thinking. For middle school age, the predominance of verbal abstract thinking, which becomes the leading one among older students, is characteristic. At this age, verbal, semantic memory predominates. With the help of oral speech, children learn written speech, and the improvement of the latter entails an even greater development of oral speech and the process of thinking. As the ability to generalize, abstract thinking develops, there is a transition from involuntary attention to arbitrary, purposeful attention. In the process of mental and physical activity of children, the upbringing and training of voluntary and involuntary attention take place. Speech and thinking develop in parallel in the process of verbal communication with other people, during games, physical exercises and labor activities of children. Speech has a great influence on the mental development of children. Age-related psychology. Developmental physiology is closely related to developmental psychology, which studies the patterns of emergence, development and manifestations of the psyche of children. Its subject is the study of the content of the psyche, i.e., what exactly and how a person reflects in the world around him. The psyche is the result of the reflex, or reflective, activity of the human brain. Physiology deals with the study of only the physiological mechanisms of the brain. It is especially important to study the functions of the labor activity of the human body and his speech, which are the physiological basis of the psyche. Basic patterns of development of the human body. Throughout the entire life cycle, from birth to death, the human body undergoes a number of consistent and natural morphological, biochemical and physiological (functional) changes. A child is not a reduced copy of an adult, therefore, for teaching and raising children, one cannot simply quantitatively reduce the properties of an adult in accordance with the age, height or weight of the child. A child differs from an adult in specific features of the structure, biochemical processes and functions of the body as a whole and individual organs, which undergo qualitative and quantitative changes at various stages of his life. To a large extent, these changes are due to hereditary factors, which mainly predetermine the stages of growth and development. At the same time, such factors as education and upbringing, behavior (activity of skeletal muscles), nutrition and hygienic living conditions, and puberty are of decisive importance for the manifestation of hereditary factors and new qualities of the body, the formation of age-related characteristics of children. Heterochrony and systemogenesis. According to S.I. Halperin, the growth and development of individual organs, their systems and the entire organism occur unevenly and non-simultaneously - heterochronically. The outstanding Russian physiologist P.K. proposed the doctrine of heterochrony and substantiated the resulting doctrine of systemogenesis. Anokhin. In his opinion, a functional system should be understood as “a broad functional unification of variously localized structures based on obtaining the final adaptive effect necessary at the moment (for example, a functional respiratory system, a functional system that ensures the movement of the body in space, etc.). The structure of a functional system is complex and includes afferent synthesis, decision making, the action itself and its result, back afferent from effector organs and, finally, the action acceptor, comparison of the effect obtained with the expected one. "Afferent synthesis includes processing, generalization of various types of information As a result of the analysis and synthesis of the received information, it is compared with past experience.A model of the future action is formed in the action acceptor, the future result is predicted, and the actual result is compared with the previously formed model. Various functional systems mature unevenly, they turn on in stages, gradually change, creating conditions for the body to adapt to different periods of ontogenetic development. Those structures that together will constitute a functional system of vital importance by the time of birth are laid down and mature selectively and accelerated. For example, the orbicular muscle of the mouth is innervated at an accelerated rate and long before other muscles of the face are innervated. The same can be said about other muscles and structures of the central nervous system that provide the act of sucking. Another example: of all the nerves of the hand, those that provide contraction of the muscles - the flexors of the fingers, which carry out the grasping reflex, develop the earliest and most fully. The selective and accelerated development of morphological formations that make up a full-fledged functional system that ensures the survival of the newborn is called systemogenesis. Heterochrony is manifested by periods of acceleration and deceleration of growth and development, the absence of parallelism in this process. A number of organs and their systems grow and develop non-simultaneously: some functions develop earlier, some later. Higher nervous activity. Heterochrony is determined not only by phylogenesis and its repetition in ontogeny, which is a biogenetic law; it is determined by the conditions of existence, which change at all stages of children's ontogenesis. Since the unity of the organism and its living conditions is ensured by the nervous system, a change in the conditions of existence of the organism entails a change in the functions and structure of the nervous system. Thus, in the growth and development of the body, its individual organs and systems, the main role belongs to conditioned and unconditioned reflexes. Conditioned and unconditioned reflexes constitute the highest nervous activity, provide life in a constantly changing world around. All functions of the body are caused and changed by a conditioned reflex. Congenital, unconditioned reflexes are primary, they are transformed by acquired, conditioned reflexes. At the same time, conditioned reflexes do not repeat unconditioned ones, they differ significantly from them. While maintaining the same conditions of life in a number of successive generations, some conditioned reflexes become unconditioned. In the implementation of higher nervous activity, the metabolism of the nervous system changes, therefore, over the course of many generations, its structure has also changed. As a result, the structure of the human nervous system (especially his brain) is fundamentally different from the structure of the nervous system of animals. Metabolism. Higher nervous activity plays a leading role in onto- and phylogenesis. In the current reactions of the body, mutual transitions of excitation and inhibition, as well as shifts in the relationships of the endocrine glands, are of great importance. Studies have shown that in animals the metabolism directly depends on the size of the body surface. The doubling of body weight in mammals occurs due to the same amount of energy contained in food, regardless of whether the animal grows quickly or slowly, that is, the length of time required to double the weight is inversely proportional to the metabolic rate (Rubner's rule. Specified This rule is also observed in relation to the human body, but both during growth and after the end of this period, the quantitative and qualitative differences in the metabolism of the human body do not completely depend on this rule.After growth, mammals consume the same amount of energy per 1 kg of body weight, For a person, this figure is almost four times higher.This is due to the social conditions of a person's life, mainly with his work activity. muscle activity. Skeletal muscles play an exceptional role in human ontogenesis. During the period of muscle rest, 40% of the energy is released in the muscles, and during muscle activity the energy release increases sharply. Famous physiologist I.A. Arshavsky formulated the energy rule of skeletal muscles as the main factor that allows us to understand both the specific features of the physiological functions of the body at different age periods and the patterns of individual development. The rule states that “the characteristics of energy processes in different age periods, as well as changes and transformations in the activity of the respiratory and cardiovascular systems in the process of ontogenesis depend on the corresponding development of skeletal muscles.” Human movement is a necessary condition for its existence. They make up his behavior, are made in the process of labor, in the course of communication with others through speech, while satisfying physiological needs, etc. Movements are the key to good health and positive emotions. This means that a person's motor activity is due to social and physiological necessity and needs, and not to a subjective factor - love for muscle sensations (kinesophilia). During muscular activity, the amount of information that comes from the environment through external sensory organs - exteroreceptors - increases significantly. This information plays a leading role in the reflex regulation of physical and mental performance. The nerve impulses coming from the exteroreceptors cause changes in the functions of all internal organs. This leads to a change (increase) in the metabolism and blood supply of the nervous system, motor apparatus and internal organs, which ensures the strengthening of all body functions, accelerating its growth and development during muscle activity. The nature, intensity and duration of the muscular activity of children and adolescents depend on social conditions: communication with other people through speech, training and education, especially physical, participation in outdoor games, sports and work activities. The behavior of children and adolescents at school, outside of school, in the family, their participation in socially useful activities are determined by social laws. When the nature of the functioning of skeletal muscles changes, reflex changes in the structure and functions of the nervous system occur, age-related differences arise in the structure and development of the skeleton and locomotor apparatus, innervation of internal organs, their growth and development (primarily for the organs of the cardiovascular, respiratory and digestive systems). ). The physiological mechanism of this action is that with the tension of the skeletal muscles and their contractions, special receptors, proprioreceptors, which are present in them, in the joints and tendons, are irritated. The main functions of proprioceptors are: a) irritation during muscular activity is a prerequisite for regulating movements by the nervous system, correcting their coordination, and forming new motor reflexes and skills; b) ensuring, as a result of the influx of centripetal impulses from proprioreceptors into the nervous system, its high performance, especially the brain (motor-cerebral reflexes); c) reflex regulation of the work of internal organs - provides coordination of movements and changes in the functions of internal organs (motor-visceral reflexes). Thus, muscular activity is the main condition for mental and physical performance. Irritation of proprioreceptors, the action of metabolic products that are formed during muscle activity, and the entry of hormones into the blood as a result of a reflex enhancement of the functions of the endocrine glands - all this changes the metabolism and leads to age-related changes in the growth and development of the body as a whole and its individual organs. First of all, those organs grow and develop that bear the greatest load during contractions of skeletal muscles, as well as those whose muscles function more. The accumulation of substances and energy in the structure of the body due to growth ensures further growth and development, increases the efficiency, and the improvement of the physiological mechanisms of metabolism regulation contributes to a more economical use of substances and energy, leads to a decrease in the level of metabolism per unit body weight. The development of inhibition in the nervous system directly depends on the functions of the skeletal muscles: the onset of inhibition coincides with the appearance of skeletal muscle tone, which ensures static immobility or movement of the body in space. Critical periods of growth and development largely depend on changes in the nature of the tone of the skeletal muscles and its contractions. Thus, the transition from the infantile period of development to the preschool (or nursery) is associated with the development of a static posture, walking, and the beginning of mastering speech. This activity of the skeletal muscles causes changes in the structure of the nervous system and the improvement of its functions, the structure of the skeleton and skeletal muscles, the regulation of the cardiovascular and respiratory systems, an increase in the volume and weight of the heart, lungs and other internal organs. Termination of breastfeeding, changes in the consistency and composition of food and the appearance of milk teeth lead to a restructuring of the digestive canal, changes in its motor and secretory functions and absorption. The level of metabolism per 1 kg of body weight increases significantly due to the participation of tone and contractions of skeletal muscles not only in the movement of the body, but also in heat production at rest. By the end of the preschool period, running mechanisms are formed, and speech functions continue to develop. In the preschool period, the maintenance of a relative constancy of body temperature at rest by tension of the skeletal muscles ceases; with the onset of preschool age, the skeletal muscles at rest completely relax. The motor neurons of the brain acquire a shape characteristic of an adult, the weight of the brain increases significantly (it becomes three times larger than that of a newborn). Improving the functions of the brain (especially the mechanism of inhibition) leads to a decrease in the level of metabolism per 1 kg of body weight, the appearance of an inhibitory effect of the nervous system on cardiac and respiratory activity, an increase in the period of wakefulness and a decrease in the period of sleep. During the period of transition to primary school age, the muscles of the hands develop rapidly, the simplest labor and household motor skills are formed, small precise hand movements begin to be developed. Changes in motor activity are associated with the beginning of schooling, especially with learning to write and the simplest work. As a result of the complication and increase in the number of movements and great mobility, by the beginning of primary school age, the development of brain neurons basically ends, and its functions are improved. First of all, this applies to braking, which ensures the coordination of subtle and precise movements. Basically, by this age, the formation of the inhibitory effect of the nervous system on the heart is completed, the weight of the heart and lungs increases, and the improvement of the regulation of metabolism entails a decrease in its level by 1 kg of body weight. When changing milk teeth to permanent ones, a further restructuring of the digestive canal occurs, which is associated with the consumption of food corresponding to an adult. The transition to middle school or adolescence is characterized by the onset of puberty, a change in the functions of skeletal muscles, their increased growth and development, and the mastery of motor skills of labor and physical exercise. There is a completion of the morphological maturation of the motor apparatus, which has almost reached a fairly perfect level of functioning, characteristic of adults. At the same time, the formation of the motor zone in the brain practically ends, the frequency of the pulse and respiration decreases, and there is a further decrease in the relative level of metabolism, which, nevertheless, is even more than in an adult. The change of milk teeth to permanent ones is completed. The transition to adolescence is characterized by increased muscle growth and the formation of massive muscle fibers, a sharp increase in their strength and a significant complication and expansion of the motor apparatus. The weight of the brain and spinal cord almost reaches the level of an adult. The process of ossification of the sesamoid bones begins. There is another proof of the dependence of the growth and development of children on the activity of skeletal muscles: in cases where, due to a disease (for example, inflammation of the motor nerves), movement is restricted, there is a delay in the development of not only skeletal muscles and the skeleton (for example, the development of the chest), but also a sharp slowdown in the growth and development of internal organs - the heart, lungs, etc. Children who have had poliomyelitis and therefore are significantly limited in movement differ from non-sick children in a higher frequency of heartbeats and respiratory movements of the chest. In children deprived of the opportunity to perform normal dynamic work, inhibition of the work of the heart and respiration is observed, therefore, the frequency of respiration and heart contractions is the same as in younger children. Reliability of biological systems. On the general laws of individual development, the famous Soviet physiologist and teacher A.A. Markosyan proposed to include the reliability of biological systems, which is usually understood as “a level of regulation of processes in the body that ensures their optimal course with the urgent mobilization of reserve capabilities and interchangeability, guaranteeing adaptation to new conditions, and with a rapid return to the original state.” In accordance with this concept, the entire path of development from conception to death takes place in the presence of a supply of life opportunities. This reserve ensures the development and optimal course of life processes under changing environmental conditions. For example, in the blood of one person there is such an amount of thrombin (an enzyme involved in blood clotting) that is enough to clot the blood of 500 people. The femur is able to withstand a 1500 kg stretch, and the tibia does not break under the weight of a load of 1650 kg, which is 30 times the usual load. A huge number of nerve cells in the human body is also considered as one of the possible factors for the reliability of the nervous system. 1.2. Age periodization Passport age, where the inter-age interval is equal to one year, differs from biological (or anatomical and physiological) age, covering a number of years of a person's life, during which certain biological changes occur. What criteria should be put in the basis of age periodization? To date, there is no single point of view on this issue. Some researchers base periodization on the maturation of the gonads, the rate of growth and differentiation of tissues and organs. Others consider the so-called skeletal maturity (bone age) to be the starting point, when the time of the appearance of ossification sites and the onset of a fixed connection of bones is determined radiologically in the skeleton. As a criterion for periodization, such a sign as the degree of development of the central nervous system (in particular, the cerebral cortex) was also put forward. The German physiologist and hygienist Max Rubner, in the theory of the energy rule of the surface, suggested using the features of energy processes occurring in different age periods as a criterion. Sometimes, as a criterion for age periodization, the method of interaction of the organism with the corresponding environmental conditions is used. There is also an age periodization based on the allocation of periods of newborn, toddler, preschool and school age in children, which reflects the existing system of child care institutions rather than age characteristics. The classification proposed by the Russian pediatrician, the founder of the St. Petersburg school of pediatricians, who studied the age-related anatomical and physiological characteristics of children, N.P. Gundobin. In accordance with it, they distinguish: ▪ period of intrauterine development; ▪ newborn period (2-3 weeks); ▪ infancy period (up to 1 year); ▪ pre-school (from 1 year to 3 years); ▪ preschool age (from 3 to 7 years, period of baby teeth); ▪ junior school age (from 7 to 12 years); ▪ middle, or teenage, age (from 12 to 15 years); ▪ senior school, or youth, age (from 14 to 18 years for girls, from 15-16 years to 19-20 years for boys). Developmental and educational psychology more often uses periodization based on pedagogical criteria, when periods of preschool age are divided according to kindergarten groups, and at school age three stages are distinguished: junior (I-IV grades), middle (IV-IX grades), senior (X -XI classes). In modern science, there is no single generally accepted classification of periods of growth and development and their age limits, but the following scheme is proposed: 1) newborn (1-10 days); 2) infancy (10 days - 1 year); 3) early childhood (1-3 years); 4) the first childhood (4-7 years); 5) second childhood (8-12 years old for boys, 8-11 years old for girls); 6) adolescence (13-16 years for boys, 12-15 years for girls); 7) adolescence (17-21 years for boys, 16-20 years for girls); 8) mature age: I period (22-35 years for men, 22-35 years for women); II period (36-60 years for men, 36-55 years for women); 9) old age (61-74 years for men, 56-74 years for women); 10) senile age (75-90 years); 11) centenarians (90 years and above). This periodization includes a set of features: the size of the body and organs, weight, ossification of the skeleton, teething, the development of endocrine glands, the degree of puberty, muscle strength. The scheme takes into account the characteristics of boys and girls. Each age period is characterized by specific features. The transition from one age period to another is called a turning point in individual development, or a critical period. The duration of individual age periods is largely variable. The chronological framework of age and its characteristics are determined primarily by social factors. 1.3. Acceleration of growth and development Acceleration, or acceleration (from the Latin acceleratio - acceleration), is the acceleration of the growth and development of children and adolescents compared to previous generations. The phenomenon of acceleration is observed primarily in economically developed countries. The term "acceleration" was introduced into scientific use by E. Koch. Most researchers understood acceleration as the acceleration of mainly the physical development of children and adolescents. Subsequently, this concept was significantly expanded. Acceleration began to be called an increase in body size and the onset of maturation at an earlier date. Traditionally, body length, chest volume and body weight were considered as the most important signs of physical development. But, given that the morphological features of the body are closely related to its functional activity, a number of authors began to consider the vital capacity of the lungs, the strength of individual muscle groups, the degree of ossification of the skeleton (in particular, the hand), eruption and change of teeth, the degree of sexual intercourse as signs of physical development. maturation. In addition, the proportions of the body began to be attributed to the essential features. At present, the concept of acceleration has become so broad that, referring to acceleration, they speak of both the acceleration of the physical development of children and adolescents, and the increase in the size of the body of adults, the later onset of menopause. Therefore, such a concept as a secular trend (secular trend) is often used, understanding it as a trend that has been observed for about a century, to accelerate the physical development of the whole organism - from the intrauterine period to adulthood. The acceleration was most noticeable in children in the second half of the 1965th century. So, body weight began to double at an earlier age (in 1973-4 - at 5-1940 months, in 1941-5 - at 6-1984 months). There was an earlier change of milk teeth to permanent ones (in 5 - from 6-1953 years old, in 6 - from 7-10 years old). The timing of puberty has shifted. So, the age of menstruation in the twentieth century. decreased every 1974 years by about four months and in 12,7 averaged 1930 years. There was an acceleration in the development of secondary sexual characteristics. In children and adolescents, earlier morphological stabilization was observed. The whole process of ossification ended in boys two, and in girls three years earlier than in the XNUMXs. In connection with acceleration, growth also ends earlier. At 16-17 years old in girls and at 18-19 years old in boys, ossification of long tubular bones is completed and growth in length stops. Over the past 13 years, Moscow boys of the age of 80 have become 1 cm taller, and girls - by 14,8 cm. Thus, as a result of the accelerated development of children and adolescents, they have achieved higher rates of physical development. It must be said that there is also information about the lengthening of the childbearing period: over the past 60 years it has increased by eight years. In women in Central Europe, over the past 100 years, menopause has shifted from 45 to 48 years; in Russia, this time is on average 50 years, and at the beginning of the century it was 43,7 years. Reasons for acceleration. To date, no single generally accepted point of view has been formed on the origin of the acceleration process, although many hypotheses and assumptions have been put forward. So, most scientists consider the determining factor in all shifts in the development of changes in nutrition. They associate acceleration with an increase in the content of high-grade proteins and natural fats in food, as well as with a more regular consumption of vegetables and fruits throughout the year, enhanced fortification of the body of the mother and child. There is a heliogenic theory of acceleration. In it, an important role is given to the effect of sunlight on the child: it is believed that children are now more exposed to solar radiation. However, this argument does not seem convincing enough, since the process of acceleration in the northern countries is no less rapid than in the southern ones. There is a point of view on the connection of acceleration with climate change: it is believed that humid and warm air slows down the process of growth and development, and a cool dry climate contributes to the loss of heat by the body, which supposedly stimulates growth. In addition, there are data on the stimulating effect on the body of small doses of ionizing radiation. Some scientists cite a general decline in morbidity in infancy and childhood, coupled with improved nutrition, as an important reason for the acceleration due to advances in medicine. It is also obvious that the development of science and technological progress contribute to the emergence of many new factors affecting humans, and the properties of these factors and the features of their effects on the body are still poorly understood (we are talking about chemicals used in industry, agriculture, everyday life, new medicines and etc.). Some researchers assign a significant role in acceleration to new forms and methods of upbringing and education, sports, and physical education. Acceleration is also associated with the negative impact of the pace of modern urban life. This and abundant artificial lighting (including advertising); stimulating effect of electromagnetic oscillations arising from the operation of television and radio stations; city noise, traffic; the influence of radio, film and television on early intellectual, especially sexual, development. Technological progress in economically developed countries has led to the concentration of the population in large cities. The development of transport and communications has shortened distances that previously seemed very significant. Increased migration of the population. The geography of marriage has expanded, genetic isolation is collapsing. This creates fertile ground for changes in heredity. The younger generation grows taller and matures earlier than their parents. Acceleration is a subject of study not only in biology and medicine, but also in pedagogy, psychology and sociology. Thus, experts note a certain gap between the biological and social maturity of young people, while the first comes earlier. In this regard, a number of questions arise before medical theory and practice. For example, there was a need to define new norms for labor and physical activity, nutrition, standards for children's clothing, shoes, furniture, etc. 1.4. Age anatomical and physiological features Each age period is characterized by quantitatively determined morphological and physiological parameters. The measurement of morphological and physiological indicators that characterize the age, individual and group characteristics of people is called anthropometry. Height, weight, chest circumference, shoulder width, lung capacity and muscle strength are all the main anthropometric indicators of physical development. Growth, development and their changes in certain age periods. Children grow and develop constantly, but the rates of growth and development differ from each other. In some age periods growth predominates, in others - development. The unevenness of growth and development rates and their undulation also determine the division into age periods. So, up to 1 year of life, growth predominates in a child, and from 1 year to 3 years - development. From 3 to 7 years old, the growth rate accelerates again, especially at 6-7 years old, and the rate of development slows down; from 7 to 10-11 years old, growth slows down and development accelerates. During puberty (from 11-12 to 15 years), growth and development accelerate sharply. Age periods of growth acceleration are called stretching periods (up to 1 year, from 3 to 7, from 11-12 to 15 years), and some slowdown in growth - rounding periods (from 1 to 3, from 7 to 10-11 years). Separate parts of the body grow and develop disproportionately, that is, their relative sizes change. For example, the size of the head relatively decreases with age, while the absolute and relative length of the arms and legs increases. The same can be said about the internal organs. In addition, there are also gender differences in the growth and development of children. Until about 10 years old, boys and girls grow almost the same. From 11-12 years old girls grow faster. During puberty in boys (from 13-14 years old), the growth rate increases. At the age of 14-15, the growth of boys and girls is almost equal, and from the age of 15, boys grow faster again, and this predominance of growth in men persists throughout life. Then the growth rate slows down and basically ends by the age of 16-17 in girls, by 18-19 in boys, but slow growth continues until 22-25 years. The length of the head of young men is 12,5-13,5%, torso - 29,5-30,5%, legs - 53-54%, arms - 45% of the total body length. In terms of growth rate, the shoulder is in the first place, the forearm is in the second place, the hand grows more slowly. The greatest increase in the length of the trunk occurs about a year after the greatest increase in the length of the legs. As a result, the length of the body of an adult is approximately 3,5 times greater than the length of the body of a newborn, the height of the head is twice, the length of the body is three times, the length of the arm is four times, the length of the leg is five times. Due to the discrepancy in the rates of growth and development, there is no strictly proportional relationship between height and weight, but, as a rule, at the same age, the greater the height, the greater the weight. The rate of weight gain is greatest in the first year of life. By the end of the first year, the weight has tripled. Then the weight gain averages 2 kg per year. Like height, the weight of boys and girls up to 10 years old is approximately the same, with a slight lag in girls. From 11-12 years old, the weight of girls is more associated with the development and formation of the female body. This predominance of weight remains with them until about 15 years of age, and then, due to the predominance of growth and development of the skeleton and muscles, the weight of the boys increases, and this excess of weight persists in the future. Age differences in the increase in the absolute and relative weight of individual organs are also significant. For example, the circumference of the chest from the age of 7 is greater in boys, and from the age of 12 in girls. By the age of 13, it is almost the same in both sexes (girls have a little more), and from the age of 14, the circumference of the chest is larger in boys. This difference persists and increases in the future. The width of the shoulders in boys from 6-7 years old begins to exceed the width of the pelvis. Generally speaking, the width of the shoulders in children increases annually, especially between 4-7 years of age. This annual increase is greater for boys than for girls. 1.5. Hygiene of the educational process at school School education is the result of the joint activity of the teacher and the student. In this regard, it is necessary to distinguish between the hygiene requirements for both the teacher and the student. This helps, on the one hand, to develop a system of individual actions of the student, which includes planning all stages of educational activities, preparation and maintenance in order of the workplace, performing tasks in accordance with the principle from easy to difficult, from simple to complex, etc. on the other hand, the rational distribution of the teacher's workload during the day, the elimination of breaks between lessons, taking into account the difficulty of the subject when scheduling, providing the maximum opportunity for expanding knowledge are included in the concept of the scientific organization of the teacher's work. The hygiene of pedagogical work also includes the regulation of the activities of each teacher (taking into account the increase in fatigue throughout the working day), the possibility of daily rest, rest on weekends, a change of activity during the holidays, a good rest in the summer. Scientific and hygienic principles of children's labor. Mental work is a product of the activity of cells in the cerebral cortex, which in children is usually accompanied by motor activity - muscle work. Muscular work, in turn, is associated with the activity of the central and peripheral nervous system. Thus, the student’s work is the product of a mandatory combination of mental and physical labor. The scientific and hygienic organization of the work of a schoolchild includes the organization of the educational and educational process, as well as recreation, taking into account the physiological capabilities of the child. This includes the creation of optimal conditions that contribute to the preservation of the child's working capacity, his normal growth and development, and the strengthening of his health. Consequently, all aspects of the education and upbringing of children (observance of the daily routine, age regulation of the load on the nervous system and muscular apparatus, proper organization of life, good rest) should be closely interconnected. Insufficient satisfaction of the physiological needs of the child leads to the suppression of normal life functions, a decrease in resistance to adverse factors, an increase in susceptibility to infectious diseases, a disruption in the relationship between body systems, and a negative effect on higher nervous activity. In hygiene, considerable attention is paid to the observance of physiological norms that affect the child's abilities. The main limiting factors are fatigue and overwork. Fatigue and overwork. The result of any sufficiently long work is fatigue of the body due to the fact that in the process of activity the energy reserves accumulated in the cells and necessary for work are gradually depleted. The gradual increase in mental fatigue is expressed in a decrease in performance: the quantity and quality of what is done decreases, interest in work decreases, the coordination of individual operations is disrupted, attention is scattered, memory is weakened, and uncertainty appears. A temporary decrease in the performance of brain tissue cells and the entire body as a whole is called fatigue. This is a natural physiological phenomenon. The physiological nature and nervous mechanisms of mental fatigue are explained by the classical reflex theory of Sechenov-Pavlov, according to which the source of the feeling of fatigue is "exclusively in the central nervous system", and not in the muscles, as previously thought. Fatigue of cortical cells I.P. Pavlov considered them as their "functional destruction", and the inhibition that occurs in them - as a process that prevents further destruction and enables cells to restore their normal state. Thus, fatigue is a natural temporary physiological state of the body. It cannot be avoided, but the skillful use of the method of work and the timely unloading of the body make it possible to delay fatigue for some time. Signs of fatigue in children usually appear by the end of the fourth or fifth lesson: lethargy, absent-mindedness, drowsiness occur, attention is poorly concentrated, discipline violations are possible. If the fatigue that has arisen is not replaced by rest, then overwork occurs, which is very harmful to the body, since it is associated with an excess of the functional capabilities of the cortical cells and is prohibitive. Overfatigue of schoolchildren is associated with excessive workload, combining academic work and classes in circles, music, sports schools, violation of the daily routine and rules of personal hygiene. Usually, overwork appears immediately after overload, but it can also occur after a while. For example, if during the summer holidays the child’s rest is organized incorrectly, then at the beginning of the school year this may not affect academic performance, however, the performance of such a student will decrease much earlier than that of a normally rested child. To eliminate acute (quick and single) fatigue, as a rule, it is enough to get enough sleep at night. Systematic fatigue and overwork is not eliminated by one normal sleep. This requires rest for at least two weeks, high-calorie nutrition with an abundance of vitamins, water procedures, appropriate organization of sleep. The use of tonics and drinks is undesirable. To prevent fatigue, it is necessary to properly and rationally organize the work of the student. This is ensured by the efforts of the teacher, since the children themselves are not yet capable of this due to age characteristics. The concept of a child’s “school maturity”. In Russia, compulsory schooling for children is introduced from the age of 6-7 years. As a rule, by this time the child’s body is morphologically and functionally prepared for learning. Nevertheless, a child’s entry into school is a turning point in his life, breaking the stereotype developed in preschool institutions and the family. The most difficult for most students are usually the first 2-3 months of study. It is even possible the occurrence of such a condition, which is defined by doctors as an adaptive disease (it is also called "school stress" or "school shock"). The task of the teacher is to facilitate the period of adaptation of the child to new conditions, that is, to reduce the neuropsychological trauma of the transition period from preschool to school life. The concept of school maturity, i.e., the child's functional readiness for learning, is one of the important problems of age-related physiology, pedagogy, psychology, and school hygiene. It is associated with a characteristic of the level of physical, mental and social development at which the child becomes receptive to systematic training and education at school. Teachers, doctors, psychologists must take into account the degree of school maturity, since children who have not reached this level become unsuccessful students. To determine the degree of school maturity, they use the test proposed in 1955 by the German psychologist A. Kern and improved by I. Irasek in 1966. The Kern-Irasek test consists of the following tasks: the child is asked to draw a person and points arranged in a certain order, according to memory after their demonstration and copy the phrase written in cursive. The work is evaluated on a five-point system - from 1 (best mark) to 5 (worst mark). The sum of points for individual tasks is a general indicator. Children who have received from 3 to 5 points for completing three tasks of the test are considered ready for systematic learning. Getting 6-8 points indicates the need for additional preparation of children for school (these are the so-called middle-aged children). A score of 9 or more points indicates unpreparedness for schooling. Individual approach to children. Whether students will become interested in the lesson depends on the skill of the teacher, on his ability to present the material taking into account the age characteristics of the students, as well as on the physical condition of the children, the type of their higher nervous activity and functional capabilities. Most often, the composition of students in the class is heterogeneous: there are children with poor health and a lower level of training, who need individual treatment and the selection of special material for homework, consultations, and additional classes. For children suffering from chronic diseases (rheumatism, tuberculosis intoxication), there is one day a week free from school, when they work at home on the instructions of teachers. The decision to grant the child a day off from school is made by the teachers' council on the basis of medical documents. First of all, children who live at a distance of 500 m and further from the school apply for such a benefit. 1.6. Hygienic basics of the daily routine of students The daily routine is a dynamic system of load distribution and rest, which ensures the conservation of strength and energy for the normal functioning of the body. The daily regimen of the child is based on a comprehensive consideration of the characteristics of his growth, development, living conditions and is designed to establish the physiological balance of the body with the environment in which education and upbringing are carried out. Thus, the mode is the basis of the health-improving and preventive effect on the body of all factors of educational work. Justification for students' daily routine. The regimen should take into account the age characteristics of the child, include the normal duration of sleep for him, his stay in general education and special (music, art, sports) schools. Any element of a schoolchild’s daily routine should be carried out in favorable conditions (for example, you need to prepare for lessons in a cozy and hygienically properly equipped place, sleep in a well-ventilated room, etc.). To help the child and his parents draw up a scientifically based student's daily routine, the class teacher at the parent meeting informs about the approximate daily routine, explaining the purpose of each element of the routine for the student's progress and health. Here are some of those recommendations. The child should get up after a night's sleep at 7-7.30 in the morning. This is acceptable for first and second shift students. Then the child does morning exercises, goes to the toilet, has breakfast and goes to school, where he must come 10-15 minutes before the start of classes to prepare for the lesson. The child should return home at about the same time, this brings up punctuality and saves time. The student should go home slowly so as not to waste extra energy and be able to be in the fresh air. At home, the student changes clothes, washes his hands and has lunch. After that, younger students (especially first-graders and children who have had illnesses) should sleep for 1-1,5 hours, which is necessary to restore strength and strengthen the nervous system. Healthy students, starting from the second grade, after lunch can relax in the fresh air, for example, skiing, skating, sledding, playing outdoor games, etc. After that, the child starts doing homework (primarily of medium and advanced difficulty). 1,5-2 hours before bedtime, children have dinner. schedule of lessons. The alternation of academic disciplines in the lesson schedule ensures a switch in the activity of the cerebral cortex and therefore prevents children from becoming tired and meets pedagogical requirements. There are four lessons in grades I-III. In grade IV, it is allowed (no more than twice a week) to increase the number of lessons to five. In grades V-IX there are five lessons daily, in grades X-XI - six lessons each. The performance of schoolchildren during the school day is different. Initially, it increases and reaches a maximum (in the second lesson in the lower grades and in the third in the older grades), and then begins to decline due to the onset and increase of fatigue. The last (fifth or sixth) lesson is the most difficult for many children. The teacher should organize it in such a way as to keep the students working longer. The working capacity of students also differs during the week: in the first days it is higher, by the end of the week it decreases. Thus, when drawing up a schedule, it is necessary to alternate objects so that the degree of mental stress corresponds to the working capacity of the body. The largest study load should be in the middle of the week, the smallest - on Monday and Saturday. In order for the children to fully rest, students of grades I-IV are recommended not to give assignments at all on weekends and significantly reduce them to students of middle school age. The same goes for vacations. Duration of the academic year. The academic year in secondary schools begins on September 1. It consists of four academic quarters, which are separated by holidays of varying lengths. Analyzing the fatigue of children during a quarter and a year as a whole, scientists noticed that the decrease in working capacity is especially noticeable towards the end of these periods. However, properly organized rest contributes to its restoration. It is recommended that on the first day after the holidays, the lessons begin with a repetition of the material covered. Thus, a kind of bridge is created from the known, but forgotten, to the unknown, which has to be known and learned. This principle has a physiological and hygienic basis - the breaking of conditioned connections and the prevention of fatigue. Physiological and hygienic justification for lesson duration and breaks. The educational process at school varies according to age. A lesson in a general education school lasts 45 minutes, but as a result of studying performance, scientists came to the conclusion that for first-grade students this load significantly exceeds the norm and the lesson for them should be reduced to 35 minutes. Research on the duration of active attention confirms this. For example, for seven-year-old children, the period of active attention is 10-12 minutes, for ten-year-olds - 16-20 minutes, for eleven- to twelve-year-olds - up to 25 minutes, for older schoolchildren - up to 30 minutes. It follows that the duration of explanation of new material in each age group should not exceed the duration of the period of active attention. In the course of studying the dynamics of the productivity of students' work, it was found that in the classroom (especially in the primary grades) it is impossible to use only one type of activity in working with children, it must be diversified, switching children from one type of work to another. This is due to the fact that when changing the type of activity, the nature of the stimuli changes, as a result of which various analyzers and, consequently, different parts of the cerebral cortex are excited, giving the possibility of inhibition to previously functioning cells and thereby prolonging the working capacity of schoolchildren. In addition, a special place in the change of activity is occupied by physical culture pauses conducted by the teacher. They also help relieve fatigue. In the lower grades, physical education pauses are carried out from the second lesson, and in the older ones - from the third. The signal for their implementation is the beginning of a decrease in working capacity: in the lower grades this happens after 25-30 minutes from the beginning of the lesson, and in the older ones - after 30-35 minutes. For students of grade I in the first quarter, physical culture breaks are recommended twice per lesson - after 15-20 and 30-35 minutes. The duration of the pauses is determined by the teacher leading the lesson. It should be noted that in students of grades I-II, the first signal system prevails over the second. In this regard, when organizing a lesson, it is necessary, relying on the sensory perception of the subject, to use visual aids, to involve visual, auditory and motor analyzers in the field of activity, and if possible, also touch. An important role in the organization of the lesson is played by the observance of hygiene standards and rules for seating students at their desks (tables), the creation of an air-thermal regime, etc. The breaks between lessons are designed to allow students and teachers to relax, as well as to allow students to move to the classrooms, laboratories and classrooms in which the next lessons will be held. Proper physiological and hygienic change is a prerequisite for full-fledged work in the next lesson. Changes last 10 minutes, and after the second lesson - 30 minutes. In some cases, instead of one thirty-minute break, two twenty-minute breaks are allowed (after the second and third lessons). Other reductions are unacceptable because they increase the workload on students and predispose to the development of overwork and, therefore, neuroses. During the break, children rest from mental activity. Breaks should not be used to prepare for the next lesson. Pupils go to a ventilated recreational room or to an open sports ground (depending on the weather). Hot breakfasts are offered at the big break. Author: Antonova O.A. << Back: Accepted abbreviations >> Forward: The influence of heredity and environment on the development of the child’s body (Heredity and its role in the processes of growth and development. Man and plants. Man and animals. The influence of viruses on the human body. Hygiene of clothing and footwear)
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