Age anatomy and physiology (a manual for OZO). Theoretical foundations of age-related physiology (developmental physiology) of a child
Current page: 1 (total book has 12 pages) [accessible reading excerpt: 8 pages]
Yuri Savchenkov, Olga Soldatova, Sergei Shilov
Age physiology (physiological characteristics of children and adolescents). Textbook for universities
Reviewers:
Kovalevsky V. A. , Doctor of Medical Sciences, Professor, Head of the Department of Childhood Psychology, Krasnoyarsk State Pedagogical University them. V. P. Astafieva,
Manchuk V. T. , MD, Corresponding Member RAMS, Professor of the Department of Polyclinic Pediatrics, KrasSMU, Director of the Research Institute of Medical Problems of the North, Siberian Branch of the Russian Academy of Medical Sciences
© VLADOS Humanitarian Publishing Center LLC, 2013
Introduction
The child's body is an extremely complex and at the same time very vulnerable socio-biological system. It is in childhood that the foundations of the health of the future adult are laid. An adequate assessment of the physical development of a child is possible only if the characteristics of the corresponding age period are taken into account, and the vital signs of this child are compared with the standards of his age group.
Age physiology studies the functional features of the individual development of the body throughout its life. Based on the data of this science, methods of teaching, educating and protecting the health of children are being developed. If the methods of education and training do not correspond to the capabilities of the body at any stage of development, the recommendations may turn out to be ineffective, cause a negative attitude of the child to learning, and even provoke various diseases.
As the child grows and develops, almost all physiological parameters undergo significant changes: blood counts, the activity of the cardiovascular system, respiration, digestion, etc. change. Knowledge of various physiological parameters characteristic of each age period is necessary to assess the development of a healthy child.
In the proposed publication, the features of the age-related dynamics of the main physiological parameters of healthy children of all age groups are summarized and classified according to systems.
The manual on age physiology is an additional educational material on the physiological characteristics of children of different ages, which is necessary for mastering by students who study in pedagogical higher and secondary specialized educational institutions and are already familiar with the general course of human physiology and anatomy.
Each section of the book provides short description the main directions of ontogenesis of indicators of a particular physiological system. In this version of the manual, the sections “Age characteristics of higher education” are significantly expanded. nervous activity and mental functions", "Age-related features of endocrine functions", "Age-related features of thermoregulation and metabolism".
This book contains descriptions of numerous physiological and biochemical parameters and will be useful in practical work not only future teachers, defectologists, child psychologists, but also future pediatricians, as well as already working young professionals and high school students who want to replenish their knowledge of the physiological characteristics of the child's body.
Chapter 1
Age periodization
Patterns of growth and development of the child's body. Age periods of child development
A child is not an adult in miniature, but an organism, relatively perfect for each age, with its own morphological and functional features, for which the dynamics of their course from birth to puberty is natural.
The child's body is an extremely complex and at the same time very vulnerable socio-biological system. It is in childhood that the foundations of the health of the future adult are laid. An adequate assessment of the physical development of a child is possible only if the characteristics of the corresponding age period are taken into account, and the vital signs of a particular child are compared with the standards of his age group.
Growth and development are often used interchangeably. Meanwhile, their biological nature (mechanism and consequences) is different.
Development is a process of quantitative and qualitative changes in the human body, accompanied by an increase in the level of its complexity. Development includes three main interrelated factors: growth, differentiation of organs and tissues, and shaping.
Growth is a quantitative process characterized by an increase in the mass of an organism due to a change in the number of cells and their size.
Differentiation is the emergence of specialized structures of a new quality from poorly specialized progenitor cells. For example, a nerve cell that is laid down in the neural tube of an embryo (embryo) can potentially perform any nervous function. If a neuron migrating to the visual area of the brain is transplanted into the area responsible for hearing, it will turn into an auditory neuron, not a visual one.
Formation is the acquisition by the body of its inherent forms. For example, the auricle acquires the shape inherent in an adult by the age of 12.
In those cases when intensive growth processes simultaneously occur in many different tissues of the body, the so-called growth spurts are noted. This is manifested in a sharp increase in the longitudinal dimensions of the body due to an increase in the length of the trunk and limbs. In the postnatal period of human ontogenesis, such “leaps” are most pronounced:
in the first year of life, when there is a 1.5-fold increase in length and a 3-4-fold increase in body weight;
at the age of 5–6 years, when, mainly due to the growth of the limbs, the child reaches approximately 70% of the body length of an adult;
13-15 years - pubertal growth spurt due to an increase in the length of the body and limbs.
The development of the organism from the moment of birth to the onset of maturity occurs in constantly changing environmental conditions. Therefore, the development of the organism is adaptive, or adaptive, in nature.
To ensure an adaptive result, various functional systems mature non-simultaneously and unevenly, switching on and replacing each other at different periods of ontogenesis. This is the essence of one of the defining principles of the individual development of an organism - the principle of heterochrony, or non-simultaneous maturation of organs and systems and even parts of the same organ.
The terms of maturation of various organs and systems depend on their significance for the life of the organism. Those organs and functional systems that are most vital at this stage of development grow and develop faster. By combining individual elements of one or another organ with the earliest maturing elements of another organ participating in the implementation of the same function, the minimum provision of vital functions sufficient for a certain stage of development is carried out. For example, to ensure food intake at the time of birth, the circular muscle of the mouth first matures from the facial muscles; from the cervical - the muscles responsible for turning the head; of the receptors of the tongue - receptors located at its root. By the same time, the mechanisms responsible for the coordination of respiratory and swallowing movements and ensuring that milk does not enter the respiratory tract mature. This ensures the necessary actions associated with the nutrition of the newborn: the capture and retention of the nipple, sucking movements, the direction of food along the appropriate paths. Taste sensations are transmitted through the receptors of the tongue.
The adaptive nature of the heterochronous development of body systems reflects another of the general principles of development - the reliability of the functioning of biological systems. The reliability of a biological system is understood as such a level of organization and regulation of processes that is able to ensure the vital activity of an organism in extreme conditions. It is based on such properties of a living system as the redundancy of elements, their duplication and interchangeability, the speed of return to relative constancy and the dynamism of individual parts of the system. An example of the redundancy of elements can be the fact that during the period of intrauterine development, from 4,000 to 200,000 primary follicles are laid in the ovaries, from which eggs are later formed, and only 500–600 follicles mature during the entire reproductive period.
Mechanisms for ensuring biological reliability change significantly in the course of ontogeny. In the early stages of postnatal life, reliability is ensured by a genetically programmed association of links of functional systems. In the course of development, as the cerebral cortex, which provides the highest level of regulation and control of functions, matures, the plasticity of connections increases. Due to this, selective formation of functional systems occurs in accordance with a specific situation.
Another important feature of the individual development of the child's body is the presence of periods of high sensitivity of individual organs and systems to the effects of environmental factors - sensitive periods. These are periods when the system is developing rapidly and it needs an influx of adequate information. For example, for the visual system, light quanta are adequate information, for the auditory system, sound waves. The absence or deficiency of such information leads to negative consequences, up to the unformedness of a particular function.
It should be noted that ontogenetic development combines periods of evolutionary, or gradual, morphofunctional maturation and periods of revolutionary, turning points in development associated with both internal (biological) and external (social) factors. These are the so-called critical periods. The inconsistency of environmental influences with the characteristics and functional capabilities of the organism at these stages of development can have detrimental consequences.
The first critical period is considered to be the stage of early postnatal development (up to 3 years), when the most intensive morphofunctional maturation occurs. In the process further development critical periods arise as a result of a sharp change in social and environmental factors and their interaction with the processes of morphofunctional maturation. These periods are:
the age of the beginning of education (6–8 years), when the qualitative restructuring of the morphofunctional organization of the brain falls on a period of a sharp change in social conditions;
the onset of puberty is the pubertal period (in girls - 11-12 years old, in boys - 13-14 years old), which is characterized by a sharp increase in the activity of the central link of the endocrine system - the hypothalamus. As a result, there is a significant decrease in the effectiveness of cortical regulation, which determines voluntary regulation and self-regulation. Meanwhile, it is at this time that social requirements for a teenager increase, which sometimes leads to a discrepancy between the requirements and the functional capabilities of the body, which may result in a violation of the physical and mental health of the child.
Age periodization of the ontogeny of a growing organism. There are two main periods of ontogeny: antenatal and postnatal. The antenatal period is represented by the embryonic period (from conception to the eighth week of the intrauterine period) and the fetal period (from the ninth to the fortieth week). Usually pregnancy lasts 38-42 weeks. The postnatal period covers the period from birth to the natural death of a person. According to the age periodization adopted at a special symposium in 1965, the following periods are distinguished in the postnatal development of the child's body:
newborn (1–30 days);
chest (30 days - 1 year);
early childhood (1–3 years);
first childhood (4–7 years);
second childhood (8-12 years old - boys, 8-11 years old - girls);
teenage (13-16 years old - boys, 12-15 years old - girls);
youth (17–21 years old boys, 16–20 years old girls).
Considering the issues of age periodization, it must be borne in mind that the boundaries of the stages of development are very arbitrary. All age-related structural and functional changes in the human body occur under the influence of heredity and environmental conditions, that is, they depend on specific ethnic, climatic, social and other factors.
Heredity determines the potential for physical and mental development of the individual. So, for example, the short stature of African pygmies (125–150 cm) and the tall stature of the representatives of the Watussi tribe are associated with the characteristics of the genotype. However, in each group there are individuals in whom this indicator may differ significantly from the average age norm. Deviations can occur due to the impact on the body of various environmental factors, such as nutrition, emotional and socio-economic factors, the position of the child in the family, relationships with parents and peers, the level of culture of society. These factors can interfere with the growth and development of the child, or vice versa, stimulate them. Therefore, the indicators of growth and development of children of the same calendar age can vary significantly. It is generally accepted to form groups of children in preschool institutions and classes in general education schools by calendar age. In this regard, the educator and teacher must take into account the individual psychophysiological characteristics of development.
Growth and developmental delay, called retardation, or advanced development - acceleration - indicate the need to determine the biological age of the child. Biological age, or the age of development, reflects the growth, development, maturation, aging of the organism and is determined by a combination of structural, functional and adaptive features of the organism.
Biological age is determined by a number of indicators of morphological and physiological maturity:
according to the proportions of the body (the ratio of the length of the body and limbs);
the degree of development of secondary sexual characteristics;
skeletal maturity (the order and timing of ossification of the skeleton);
dental maturity (terms of eruption of milk and molars);
metabolic rate;
features of the cardiovascular, respiratory, neuroendocrine and other systems.
When determining the biological age, the level of mental development of the individual is also taken into account. All indicators are compared with standard indicators characteristic of a given age, gender and ethnic group. At the same time, it is important to take into account the most informative indicators for each age period. For example, in the pubertal period - neuroendocrine changes and the development of secondary sexual characteristics.
To simplify and standardize the middle age organized group children, it is customary to consider the child's age equal to 1 month if his calendar age is in the range from 16 days to 1 month 15 days; equal to 2 months - if his age is from 1 month 16 days to 2 months 15 days, etc. After the first year of life and up to 3 years: 1.5 years include a child with an age of 1 year 3 months to 1 year 8 months and 29 days, to the second years - from 1 year 9 months to 2 years 2 months 29 days, etc. After 3 years at yearly intervals: 4 years includes children aged 3 years 6 months to 4 years 5 months 29 days, etc.
Chapter 2
Excitable tissues
Age-related changes in the structure of a neuron, nerve fiber and neuromuscular synapse
Different types of nerve cells in ontogeny mature heterochronously. Most early, even in the embryonic period, large afferent and efferent neurons mature. Small cells (interneurons) mature gradually during postnatal ontogenesis under the influence of environmental factors.
Separate parts of the neuron also do not mature at the same time. Dendrites grow much later than the axon. Their development occurs only after the birth of a child and largely depends on the influx of external information. The number of dendrite branches and the number of spines increase in proportion to the number of functional connections. The most branched network of dendrites with a large number of spines are neurons of the cerebral cortex.
Myelination of axons begins in utero and occurs in the following order. First of all, the peripheral fibers are covered with a myelin sheath, then the fibers of the spinal cord, the brain stem (medulla oblongata and midbrain), the cerebellum, and the last - the fibers of the cerebral cortex. In the spinal cord, motor fibers are myelinated earlier (by 3–6 months of life) than sensitive ones (by 1.5–2 years). Myelination of brain fibers occurs in a different sequence. Here, sensory fibers and sensory areas are myelinated earlier than others, while motor fibers are myelinated only 6 months after birth, or even later. Myelination is generally completed by 3 years of age, although growth of the myelin sheath continues until approximately 9–10 years of age.
Age-related changes also affect the synaptic apparatus. With age, the intensity of the formation of mediators in the synapses increases, the number of receptors on the postsynaptic membrane that respond to these mediators increases. Accordingly, as development increases, the speed of impulse conduction through synapses increases. The influx of external information determines the number of synapses. First of all, synapses of the spinal cord are formed, and then other parts of the nervous system. Moreover, excitatory synapses mature first, then inhibitory ones. It is with the maturation of inhibitory synapses that the complication of information processing processes is associated.
Chapter 3
Physiology of the central nervous system
Anatomical and physiological features of the maturation of the spinal cord and brain
The spinal cord fills the cavity of the spinal canal and has a corresponding segmental structure. In the center of the spinal cord is located gray matter (accumulation of nerve cell bodies), surrounded by white matter (accumulation of nerve fibers). The spinal cord provides motor reactions of the trunk and limbs, some autonomic reflexes (vascular tone, urination, etc.) and a conductive function, since all sensitive (ascending) and motor (descending) paths pass through it, along which a connection is established between various parts of the CNS.
The spinal cord develops earlier than the brain. In the early stages of fetal development, the spinal cord fills the entire cavity of the spinal canal, and then begins to lag behind in growth and ends at the level of the third lumbar vertebra by the time of birth.
By the end of the first year of life, the spinal cord occupies the same position in the spinal canal as in adults (at the level of the first lumbar vertebra). At the same time, the segments of the thoracic spinal cord grow faster than the segments of the lumbar and sacral regions. The spinal cord grows slowly in thickness. The most intensive increase in the mass of the spinal cord occurs by the age of 3 (4 times), and by the age of 20 its mass becomes like that of an adult (8 times more than that of a newborn). Myelination of nerve fibers in the spinal cord begins with the motor nerves.
By the time of birth, the medulla oblongata and the bridge are already formed. Although the maturation of the nuclei of the medulla oblongata lasts up to 7 years. The location of the bridge differs from adults. In newborns, the bridge is slightly higher than in adults. This difference disappears by 5 years.
The cerebellum in newborns is still underdeveloped. Enhanced growth and development of the cerebellum is observed in the first year of life and during puberty. Myelination of its fibers ends by about 6 months of age. The complete formation of the cellular structures of the cerebellum is carried out by the age of 7–8, and by the age of 15–16 its dimensions correspond to the level of an adult.
The shape and structure of the midbrain in a newborn is almost the same as in an adult. The postnatal period of maturation of midbrain structures is mainly accompanied by pigmentation of the red nucleus and substantia nigra. Pigmentation of the neurons of the red nucleus begins at the age of two and ends by the age of 4. Pigmentation of neurons in the substantia nigra begins from the sixth month of life and reaches a maximum by the age of 16.
The diencephalon includes two major structures: the thalamus, or optic tubercle, and the subthalamic region, the hypothalamus. Morphological differentiation of these structures occurs in the third month of intrauterine development.
The thalamus is a multinuclear formation associated with the cerebral cortex. Through its nuclei, visual, auditory and somatosensory information is transmitted to the corresponding associative and sensory zones of the cerebral cortex. The nuclei of the reticular formation of the diencephalon activate cortical neurons that perceive this information. By the time of birth, most of its nuclei are well developed. Enhanced growth of the thalamus occurs at the age of four. The size of an adult thalamus reaches 13 years.
The hypothalamus, despite its small size, contains dozens of highly differentiated nuclei and regulates most autonomic functions, such as maintaining body temperature and water balance. The nuclei of the hypothalamus are involved in many complex behavioral responses: sexual desire, hunger, satiety, thirst, fear, and rage. In addition, through the pituitary gland, the hypothalamus controls the work of the endocrine glands, and the substances formed in the neurosecretory cells of the hypothalamus itself are involved in the regulation of the sleep-wake cycle. The nuclei of the hypothalamus mature mainly by the age of 2–3 years, although the differentiation of cells of some of its structures continues up to 15–17 years.
The most intense myelination of fibers, an increase in the thickness of the cerebral cortex and its layers occurs in the first year of life, gradually slowing down and stopping by 3 years in the projection areas and by 7 years in the associative areas. First, the lower layers of the bark ripen, then the upper ones. By the end of the first year of life, as a structural unit of the cerebral cortex, ensembles of neurons, or columns, are distinguished, the complication of which continues up to 18 years. The most intense differentiation of the intercalated neurons of the cortex occurs at the age of 3 to 6 years, reaching a maximum by 14 years. The full structural and functional maturation of the cerebral cortex reaches approximately 20 years.
MM. Bezrukikh, V.D. Sonkin, D.A. farber
Age physiology: (Physiology of child development)
Tutorial
For students of higher pedagogical educational institutions
Reviewers:
doctor of biological sciences, head. Department of Higher Nervous Activity and Psychophysiology of St. Petersburg University, Academician of the Russian Academy of Education, Professor A.S. Batuev;
Doctor of Biological Sciences, Professor I.A. Kornienko
FOREWORD
Elucidation of the patterns of child development, the specifics of the functioning of physiological systems at different stages of ontogenesis and the mechanisms that determine this specificity is necessary condition ensuring the normal physical and mental development of the younger generation.
The main questions that parents, educators and psychologists should have in the process of raising and educating a child at home, in kindergarten or at school, at a consultative appointment or individual lessons, are what kind of child he is, what are his features, what option of training with him will be the most effective. Answering these questions is not at all easy, because this requires deep knowledge about the child, the patterns of his development, age and individual characteristics. This knowledge is also extremely important for the development of the psychophysiological foundations for the organization of educational work, the development of mechanisms for adaptation in the child, and the determination of the impact on him. innovative technologies etc.
Perhaps, for the first time, the importance of a comprehensive knowledge of physiology and psychology for a teacher and educator was highlighted by the famous Russian teacher K.D. Ushinsky in his work "Man as an object of education" (1876). “The art of education,” wrote K.D. Ushinsky, - has the peculiarity that it seems familiar and understandable to almost everyone, and even an easy matter to others - and the more understandable and easier it seems, the less a person is familiar with it theoretically and practically. Almost everyone admits that parenting requires patience; some think that it requires an innate ability and skill, that is, a habit; but very few have come to the conclusion that, in addition to patience, innate ability and skill, special knowledge is also needed, although our numerous wanderings could convince everyone of this. It was K.D. Ushinsky showed that physiology is one of those sciences in which "facts are stated, compared and grouped, and those correlations of facts in which the properties of the object of education, i.e., a person, are found." Analyzing the physiological knowledge that was known, and this was the time of the formation of age physiology, K.D. Ushinsky emphasized: “From this source, which is just opening up, education has almost not yet scooped.” Unfortunately, even now we cannot talk about the wide use of age-related physiology data in pedagogical science. The uniformity of programs, methods, textbooks is a thing of the past, but the teacher still does not take into account the age and individual characteristics of the child in the learning process.
At the same time, the pedagogical effectiveness of the learning process largely depends on how the forms and methods of pedagogical influence are adequate to the age-related physiological and psychophysiological characteristics of schoolchildren, whether the conditions for organizing the educational process correspond to the capabilities of children and adolescents, whether the psychophysiological patterns of the formation of basic school skills - writing and reading, as well as basic motor skills in the process of classes.
The physiology and psychophysiology of a child is a necessary component of the knowledge of any specialist working with children - a psychologist, educator, teacher, social educator. “Upbringing and education deals with a holistic child, with his holistic activity,” said the well-known Russian psychologist and teacher V.V. Davydov. - This activity, considered as a special object of study, contains in its unity many aspects, including ... physiological "(V.V. Davydov" Problems of developmental education. - M., 1986. - P. 167).
age physiology- the science of the features of the life of the body, the functions of its individual systems, the processes occurring in them, and the mechanisms of their regulation at different stages of individual development. Part of it is the study of the physiology of the child in different age periods.
A textbook on age-related physiology for students of pedagogical universities contains knowledge about human development at those stages when the influence of one of the leading factors of development - education - is most significant.
The subject of age physiology (physiology of child development) as academic discipline are the features of the development of physiological functions, their formation and regulation, the vital activity of the organism and the mechanisms of its adaptation to the external environment at different stages of ontogenesis.
THEORETICAL FOUNDATIONS OF AGE PHYSIOLOGY (DEVELOPMENTAL PHYSIOLOGY) OF A CHILD
The systemic principle of the organization of physiological functions in ontogenesis
The importance of identifying the patterns of development of the child's body and the features of the functioning of his physiological systems at different stages of ontogenesis for health protection and the development of age-appropriate pedagogical technologies determined the search for optimal ways to study the physiology of the child and those mechanisms that ensure the adaptive adaptive nature of development at each stage of ontogenesis.
According to modern ideas, which were initiated by the works of A.N. Severtsov in 1939, all functions are formed and undergo changes in the close interaction of the organism and the environment. In accordance with this idea, the adaptive nature of the functioning of the body in different age periods is determined by two the most important factors: morphological and functional maturity of physiological systems and the adequacy of the influencing environmental factors to the functional capabilities of the body.
Traditional for Russian physiology (I.M. Sechenov, I.P. Pavlov, A.A. Ukhtomsky, N.A. Bernstein. P.K. Anokhin and others) is the systemic principle of organizing an adaptive response to environmental factors. This principle, considered as the basic mechanism of the organism's life, implies that all types of adaptive activity of physiological systems and the whole organism are carried out through hierarchically organized dynamic associations, including individual elements of one or different organs (physiological systems).
A.A. Ukhtomsky, who put forward the principle of the dominant as a functional working organ that determines the adequate response of the body to external influences. Dominant, according to A.A. Ukhtomsky, is a constellation of nerve centers united by the unity of action, the elements of which can be topographically sufficiently distant from each other and at the same time tuned to a single rhythm of work. Concerning the mechanism underlying the dominant, A.A. Ukhtomsky drew attention to the fact that normal activity relies "not on once and for all a certain and staged functional statics of various foci as carriers of individual functions, but on the incessant intercentral dynamics of excitations at different levels: cortical, subcortical, medullary, spinal." This emphasized the plasticity, the importance of the spatio-temporal factor in the organization of functional associations that ensure the adaptive reactions of the organism. Ideas A.A. Ukhtomsky about functional-plastic systems for organizing activities were developed in the works of N.A. Bernstein. Studying the physiology of movements and the mechanisms of the formation of a motor skill, N.A. Bernstein paid attention not only to the coordinated work of nerve centers, but also to phenomena occurring on the periphery of the body - at working points. As early as 1935, this allowed him to formulate the position that the adaptive effect of an action can be achieved only if there is an end result in the central nervous system in some coded form - a “model of the required future”. In the process of sensory correction, by means of feedback coming from the working organs, it is possible to compare information about the activities already carried out with this model.
Expressed by N.A. Bernstein, the position on the importance of feedback in achieving adaptive reactions was of paramount importance in understanding the mechanisms of regulation of the adaptive functioning of the organism and the organization of behavior.
The classical notion of an open reflex arc has given way to the notion of a closed control loop. A very important provision developed by N.A. Bernstein, is the high plasticity of the system established by him - the possibility of achieving the same result in accordance with the "model of the required future" with an ambiguous way to achieve this result, depending on specific conditions.
Developing the idea of a functional system as an association that provides the organization of an adaptive response, P.K. Anokhin, as a system-forming factor that creates a certain ordered interaction of individual elements of the system, considered the useful result of the action. “It is the useful result that constitutes the operational factor that contributes to the fact that the system ... can completely reorganize the arrangement of its parts in space and time, which provides the adaptive result necessary in this situation” (Anokhin).
Of paramount importance for understanding the mechanisms that ensure the interaction of individual elements of the system is the position developed by N.P. Bekhtereva and her collaborators, about the presence of two systems of connections: rigid (innate) and flexible, plastic. The latter are most important for organizing dynamic functional associations and providing specific adaptive reactions in real conditions of activity.
One of the main characteristics of system software adaptive responses is the hierarchy of their organization (Wiener). Hierarchy combines the principle of autonomy with the principle of subordination. Along with flexibility and reliability, hierarchically organized systems are characterized by high energy structural and information efficiency. Separate levels may consist of blocks that perform simple specialized operations and transmit processed information to higher levels of the system, which perform more complex operations and at the same time exert a regulatory influence on lower levels.
The hierarchy of the organization, based on the close interaction of elements both at the same level and at different levels of systems, determines the high stability and dynamism of the ongoing processes.
In the course of evolution, the formation of hierarchically organized systems in ontogeny is associated with progressive complication and layering of regulation levels on top of each other that ensure the improvement of adaptive processes (Vasilevsky). It can be assumed that the same regularities take place in ontogeny.
The importance of a systematic approach to the study of the functional properties of a developing organism, its ability to form an optimal adaptive response for each age, self-regulation, the ability to actively seek information, develop plans and programs of activity is obvious.
Regularities of ontogenetic development. The concept of age norm
Of paramount importance for understanding how functional systems are formed and organized in the process of individual development is formulated by A.N. Severtsov, the principle of heterochrony in the development of organs and systems, developed in detail by P.K. Anokhin in the theory of systemogenesis. This theory is based on experimental studies of early ontogenesis, which revealed the gradual and uneven maturation of individual elements of each structure or organ, which are consolidated with elements of other organs involved in the implementation of this function, and, integrating into a single functional system, implement the principle of "minimum provision" of an integral function. . Different functional systems, depending on their importance in providing vital functions, mature at different periods of postnatal life - this is developmental heterochrony. It provides a high adaptability of the organism at each stage of ontogenesis, reflecting the reliability of the functioning of biological systems. The reliability of the functioning of biological systems, according to the concept of A.A. Markosyan, is one of the general principles of individual development. It is based on such properties of a living system as the redundancy of its elements, their duplication and interchangeability, the speed of return to relative constancy and the dynamism of individual parts of the system. Studies have shown (Farber) that in the course of ontogenesis the reliability of biological systems goes through certain stages of formation and formation. And if in the early stages of postnatal life it is provided by a rigid, genetically determined interaction of individual elements of the functional system, which ensures the implementation of elementary reactions to external stimuli and the necessary vital functions (for example, sucking), then in the course of development, plastic connections that create conditions for a dynamic electoral organization of the components of the system. On the example of the formation of the information perception system, a general pattern was established for ensuring the reliability of the adaptive functioning of the system. Three functionally different stages of its organization have been identified: Stage 1 (the neonatal period) - the functioning of the earliest maturing block of the system, which provides the ability to respond according to the "stimulus - reaction" principle; 2nd stage (first years of life) - generalized same-type involvement of elements of a higher level of the system, the reliability of the system is ensured by duplication of its elements; Stage 3 (observed from preschool age) - a hierarchically organized multi-level regulation system provides the possibility of specialized involvement of elements of different levels in information processing and organization of activities. In the course of ontogenesis, as the central mechanisms of regulation and control improve, the plasticity of the dynamic interaction of the elements of the system increases; selective functional constellations are formed in accordance with the specific situation and the task (Farber, Dubrovinskaya). This leads to the improvement of the adaptive reactions of the developing organism in the process of complicating its contacts with the external environment and the adaptive nature of functioning at each stage of ontogenesis.
It can be seen from the above that individual stages of development are characterized both by the features of the morphological and functional maturity of individual organs and systems, and by the difference in the mechanisms that determine the specifics of the interaction of the organism and the external environment.
The need for a specific description of the individual stages of development, taking into account both of these factors, raises the question of what should be considered as the age norm for each of the stages.
For a long time, the age norm was considered as a set of average statistical parameters characterizing the morphological and functional characteristics of the organism. This idea of the norm has its roots in those times when practical needs determined the need to highlight some average standards that make it possible to identify developmental deviations. Undoubtedly, at a certain stage in the development of biology and medicine, such an approach played a progressive role, making it possible to determine the average statistical parameters of the morphological and functional characteristics of a developing organism; and even now it allows solving a number of practical problems (for example, in calculating the standards of physical development, normalizing the impact of environmental factors, etc.). However, such an idea of the age norm, which absolutizes the quantitative assessment of the morphological and functional maturity of the organism at different stages of ontogenesis, does not reflect the essence of age-related transformations that determine the adaptive direction of the development of the organism and its relationship with the external environment. It is quite obvious that if the qualitative specificity of the functioning of physiological systems at individual stages of development remains unaccounted for, then the concept of the age norm loses its content, it ceases to reflect the real functional capabilities of the organism in certain age periods.
The idea of the adaptive nature of individual development has led to the need to revise the concept of the age norm as a set of average statistical morphological and physiological parameters. A position was put forward according to which the age norm should be considered as a biological optimum for the functioning of a living system, providing an adaptive response to environmental factors (Kozlov, Farber).
Age periodization
Differences in the idea of the criteria for the age norm are also determined by approaches to periodization. age development. One of the most common is the approach, which is based on the analysis of the assessment of morphological features (growth, change of teeth, weight gain, etc.). The most complete age periodization based on morphological and anthropological features was proposed by V.V. Bunak, according to whom changes in body size and associated structural and functional features reflect the transformation of the body's metabolism with age. According to this periodization, the following periods are distinguished in postnatal ontogenesis: infant, covering the first year of a child's life and including the initial (1–3, 4–6 months), middle (7–9 months), and final (10–12 months) cycles; first childhood (initial cycle 1-4 years, final - 5-7 years); second childhood (initial cycle: 8-10 years old - boys, 8-9 years old - girls; final: 11-13 years old - boys, 10-12 years old - girls); teenage (14–17 years old - boys, 13–16 years old - girls); youth (18–21 years old - boys, 17–20 years old - girls); from 21–22 years old, the adult period begins. This periodization is close to that adopted in pediatric practice (Tour, Maslov); along with morphological factors, it also takes into account social ones. Infancy, according to this periodization, corresponds to younger toddler or infancy; the period of the first childhood combines senior toddler or pre-preschool age and preschool; the period of the second childhood corresponds to the primary school age and adolescence to the senior preschool age. However, this classification of age periods, reflecting the existing system of education and training, cannot be considered acceptable, since, as is known, the question of the beginning of systematic education has not yet been resolved; the boundary between preschool and school ages requires clarification, and the concepts of junior and senior school age are rather amorphous.
According to the age periodization adopted at a special symposium in 1965, in life cycle a person before reaching adulthood, the following periods are distinguished: newborn (1-10 days); infancy (10 days - 1 year); early childhood (1–3 years); first childhood (4–7 years); second childhood (8-12 years old - boys, 8-11 years old - girls); adolescence (13–16 years old - boys, 12–15 years old - girls) and adolescence (17–21 years old - boys, 16–20 years old - girls) (The problem of human age periodization). This periodization is somewhat different from that proposed by V.V. Bunak by highlighting the period of early childhood, some displacement of the boundaries of the second childhood and adolescence. However, the problem of age periodization has not been finally resolved, primarily because all existing periodizations, including the latest generally accepted one, are not physiologically substantiated enough. They do not take into account the adaptive nature of development and the mechanisms that ensure the reliability of the functioning of physiological systems and the whole organism at each stage of ontogenesis. This determines the need to select the most informative criteria for age periodization.
In the process of individual development, the child's body changes as a whole. Its structural, functional and adaptive features are due to the interaction of all organs and systems at different levels of integration - from intracellular to intersystem. In accordance with this, the key task of age periodization is the need to take into account the specific features of the functioning of the whole organism.
One of the attempts to search for an integral criterion characterizing the vital activity of an organism was the assessment of the energy capabilities of the organism proposed by Rubner, the so-called “energy surface rule”, which reflects the relationship between the level of metabolism and energy and the size of the body surface. This indicator, which characterizes the energy capabilities of the body, reflects the activity of physiological systems associated with metabolism: blood circulation, respiration, digestion, excretion and the endocrine system. It was assumed that the ontogenetic features of the functioning of these systems should obey the "energetic rule of the surface."
However, the above theoretical propositions on the adaptive adaptive nature of development give reason to believe that age periodization should be based not so much on criteria that reflect the stationary features of the organism’s vital activity already achieved by a certain moment of maturation, but on criteria for the interaction of the organism with the environment.
The need for such an approach to the search for physiological criteria for age periodization was also expressed by I.A. Arshavsky. According to his view, age periodization should be based on criteria that reflect the specifics of the integral functioning of the organism. As such a criterion, the leading function allocated for each stage of development is proposed.
In the detailed study by I.A. Arshavsky and his colleagues in early childhood, in accordance with the nature of nutrition and the characteristics of motor acts, identified periods: neonatal, during which feeding with colostrum milk (8 days), lactotrophic form of nutrition (5–6 months), lactotrophic form of nutrition with complementary foods and the appearance of a standing posture (7-12 months), toddler age (1-3 years) - the development of locomotor acts in the environment (walking, running). It should be noted that I. A. Arshavsky attached special importance to motor activity as the leading factor in development. Criticizing the "energetic rule of the surface", I.A. Arshavsky formulated the concept of the "energy rule of skeletal muscles", according to which the intensity of the body's vital activity, even at the level of individual tissues and organs, is determined by the characteristics of the functioning of skeletal muscles, providing at each stage of development the features of the interaction of the organism and the environment.
However, it must be borne in mind that in the process of ontogenesis, the child's active attitude to environmental factors increases, the role of the higher parts of the CNS in providing adaptive reactions to external environmental factors, including those reactions that are realized through motor activity, increases.
Therefore, criteria that reflect the level of development and qualitative changes in adaptive mechanisms associated with the maturation of various parts of the brain, including the regulatory structures of the central nervous system, which determine the activity of all physiological systems and the behavior of the child, acquire a special role in age periodization.
This brings together physiological and psychological approaches to the problem of age periodization and creates the basis for the development of a unified concept of periodization of the child's development. L.S. Vygotsky considered mental neoplasms characteristic of specific stages of development as criteria for age periodization. Continuing this line, A.N. Leontiev and D.B. Elkonin attached special importance in age periodization to the "leading activity" that determines the emergence of mental neoplasms. At the same time, it was noted that the features of mental, as well as the features of physiological development, are determined both by internal (morphofunctional) factors and by external conditions of individual development.
One of the goals of age periodization is to establish the boundaries of individual stages of development in accordance with the physiological norms of the response of a growing organism to the influence of environmental factors. The nature of the body's responses to the impacts exerted directly depends on the age-related features of the functioning of various physiological systems. According to S.M. Grombach, when developing the problem of age periodization, it is necessary to take into account the degree of maturity and functional readiness of various organs and systems. If certain physiological systems are not leading at a certain stage of development, they can ensure the optimal functioning of the leading system in various environmental conditions, and therefore the level of maturity of these physiological systems cannot but affect the functional capabilities of the whole organism as a whole.
To judge which system is leading for a given stage of development and where lies the boundary of changing one leading system to another, it is necessary to assess the level of maturity and features of the functioning of various organs and physiological systems.
Thus, age periodization should be based on three levels of studying the physiology of the child:
1 - intrasystem;
2 - intersystem;
3 - a holistic organism in interaction with the environment.
The question of periodization of development is inextricably linked with the choice of informative criteria that should form its basis. This brings us back to the age norm. One can fully agree with the statement of P.N. Vasilevsky that "the optimal modes of activity of the functional systems of the body are not average values, but by continuous dynamic processes occurring in time in a complex network of co-adapted regulatory mechanisms. There is every reason to believe that the most informative are the criteria for age-related transformations that characterize the state of physiological systems in conditions of activity that is as close as possible to the one that the object of study - the child - encounters in his daily life, i.e. indicators that reflect real adaptability to conditions environment and adequacy of response to external influences.
Based on the concept of the systemic organization of adaptive reactions, it can be assumed that such indicators should primarily be considered those that reflect not so much the maturity of individual structures as the possibility and specifics of their interaction with the environment. This applies to indicators that characterize age features each physiological system separately, and to indicators of the integral functioning of the body. All of the above requires integrated approach to the analysis of age-related transformations at the intrasystem and intersystem levels.
No less important in developing the problems of age periodization is the question of the boundaries of functionally different stages. In other words, physiologically substantiated periodization should be based on the identification of stages of the "actual" physiological age.
Isolation of functionally different stages of development is possible only if there is data on the features of the adaptive functioning of various physiological systems within each year of a child's life.
Long-term studies conducted at the Institute of Developmental Physiology of the Russian Academy of Education made it possible to establish that, despite the heterochrony of the development of organs and systems, key points were identified within the periods considered as unified, which are characterized by significant qualitative morphofunctional transformations leading to adaptive rearrangements of the body. At preschool age, this is the age from 3-4 to 5-6 years, in primary school - from 7-8 to 9-10 years. In adolescence, qualitative changes in the activity of physiological systems are confined not to a certain passport age, but to the degree of biological maturity (certain stages of puberty - stages II–III).
Sensitive and critical periods of development
The adaptive nature of the development of the organism determines the need to take into account in age periodization not only the features of the morphofunctional development of the physiological systems of the body, but also their specific sensitivity to various external influences. Physiological and psychological studies have shown that sensitivity to external influences is selective at different stages of ontogenesis. This formed the basis for the concept of sensitive periods as periods of greatest sensitivity to environmental factors.
Revealing and taking into account sensitive periods of development of body functions is an indispensable condition for creating favorable adequate conditions for effective learning and maintaining the health of the child. The high susceptibility of certain functions to the influence of environmental factors should, on the one hand, be used for an effective targeted impact on these functions, contributing to their progressive development, and on the other hand, the influence of negative external environmental factors should be controlled, because it can lead to a violation of the development of the organism.
It should be emphasized that ontogenetic development combines periods of evolutionary (gradual) morphofunctional maturation and periods of revolutionary, turning points in development, which can be associated with both internal (biological) and external (social) factors of development.
An important and requiring special attention is the question of critical periods of development . In evolutionary biology, it is customary to consider the stage of early postnatal development as a critical period, characterized by the intensity of morphofunctional maturation, when the function may not be formed due to the absence of environmental influences. For example, in the absence of certain visual stimuli in early ontogenesis, their perception is not formed in the future, the same applies to the speech function.
In the process of further development, critical periods may arise as a result of a sharp change in social and environmental factors and their interaction with the process of internal morphofunctional development. Such a period is the age of the beginning of learning, when qualitative changes in the morphofunctional maturation of basic brain processes occur during a period of a sharp change in social conditions.
puberty- the beginning of puberty - is characterized by a sharp increase in the activity of the central link of the endocrine system (hypothalamus), which leads to a sharp change in the interaction of subcortical structures and the cerebral cortex, resulting in a significant decrease in the effectiveness of central regulatory mechanisms, including those determining voluntary regulation and self-regulation. In addition, social requirements for adolescents increase, their self-esteem increases. This leads to a discrepancy between socio-psychological factors and the functional capabilities of the body, which may result in deviations in health and behavioral maladaptation.
Thus, it can be assumed that the critical periods of development are due both to the intensive morphological and functional transformation of the main physiological systems and the whole organism, and the specifics of the increasingly complex interaction of internal (biological) and socio-psychological factors of development.
When considering the issues of age periodization, it must be borne in mind that the boundaries of the stages of development are very arbitrary. They depend on specific ethnic, climatic, social and other factors. In addition, the “actual” physiological age often does not coincide with the calendar (passport) age due to differences in the rate of maturation and development conditions of the organisms of different people. It follows that when studying the functional and adaptive capabilities of children of different ages, it is necessary to pay attention to the assessment of individual indicators of maturity. Only with a combination of age and individual approach to the study of the characteristics of the functioning of the child, it is possible to develop adequate hygienic and pedagogical measures that ensure the preservation of health and the progressive development of the body and personality of the child.
Questions and tasks
1. Tell us about the systemic principle of organizing an adaptive response.
2. What are the patterns of ontogenetic development? What is the age limit?
3. What is age periodization?
4. Tell us about the sensitive and critical periods of development.
Chapter 3
Before proceeding to the study of the most important regularities of the age development of an organism, it is necessary to understand what an organism is, what principles are laid down by Nature in its general design and how it interacts with the outside world.
Almost 300 years ago, it was proved that all living things consist of cells. The human body consists of several billion tiny cells. These cells are far from identical in appearance, in their properties and functions. Cells that are similar to each other combine to form fabrics. There are many types of tissue in the body, but they all belong to only 4 types: epithelial, connective, muscle and nervous. epithelial tissues form the skin and mucous membranes, many internal organs - the liver, spleen, etc. In epithelial tissues, the cells are located closely to each other. Connective tissue has very large intercellular spaces. This is how bones, cartilage are arranged, blood is also arranged - all these are varieties of connective tissue. muscular and nervous tissues are excitable: they are able to perceive and conduct an impulse of excitation. At the same time, this is the main function for the nervous tissue, while muscle cells can still contract, significantly changing in size. This mechanical work can be transferred to the bones or fluids inside the muscle sacs.
Fabrics in various combinations form anatomical organs. Each organ consists of several tissues, and almost always, along with the main, functional tissue that determines the specifics of the organ, there are elements of nervous tissue, epithelium and connective tissue. Muscle tissue may not be present in the organ (for example, in the kidneys, spleen, etc.).
Anatomical organs are folded into anatomical and physiological systems, which are united by the unity of the main function they perform. This is how the musculoskeletal, nervous, integumentary, excretory, digestive, respiratory, cardiovascular, reproductive, endocrine systems and blood are formed. All these systems together make up organism person.
The elementary unit of life is the cell. The genetic apparatus is concentrated in the cell core, i.e., localized and protected from the unexpected effects of a potentially aggressive environment. Each cell is isolated from the rest of the world due to the presence of a complexly organized shell - membranes. This shell consists of three layers of chemically and functionally different molecules, which, acting in concert, ensure the performance of many functions: protective, contact, sensitive, absorbing and releasing. The main job of the cell membrane is to organize the flow of matter from the environment into the cell, and from the cell to the outside. The cell membrane is the basis of all life activity of the cell, which dies when the membrane is destroyed. Any cell needs food and energy for its life activity - after all, the functioning of the cell membrane is also largely associated with the expenditure of energy. To organize the energy flow through the cell, there are special organelles in it that are responsible for generating energy - mitochondria. It is believed that billions of years ago, mitochondria were independent living organisms that learned in the course of evolution to use some chemical processes to generate energy. Then they entered into symbiosis with other unicellular organisms, which, thanks to this cohabitation, received a reliable source of energy, and the ancestors of mitochondria - reliable protection and a guarantee of reproduction.
The building function in the cell is performed ribosomes- factories for the production of proteins based on templates copied from the genetic material stored in the nucleus. Acting through chemical stimuli, the nucleus governs all aspects of cell life. The transmission of information inside the cell is carried out due to the fact that it is filled with a jelly-like mass - cytoplasm, in which many biochemical reactions take place, and substances of informational value can easily penetrate into the farthest corners of the intracellular space due to diffusion.
Many cells have, in addition, one or another adaptation for movement in the surrounding space. It could be flagellum(like a spermatozoon) villi(as in the intestinal epithelium) or the ability to transfuse the cytoplasm in the form pseudopodium(as in lymphocytes).
Thus, the most important structural elements of a cell are its shell (membrane), control organ (nucleus), energy supply system (mitochondrion), building block (ribosome), mover (cilia, pseudopodia, or flagellum) and internal environment (cytoplasm). Some unicellular organisms also have an impressive calcified skeleton that protects them from enemies and accidents.
Surprisingly, the human body, which consists of many billions of cells, has, in fact, the same major building blocks. Man is separated from the environment by his skin membrane. It has a mover (muscles), a skeleton, organs of control (the brain and spinal cord and endocrine system), an energy supply system (respiration and blood circulation), a primary food processing unit (gastrointestinal tract), and an internal environment (blood, lymph, interstitial fluid). This scheme does not exhaust all the structural components of the human body, but allows us to conclude that any living being is built according to a fundamentally unified plan.
Of course, a multicellular organism has a number of features and, apparently, advantages - otherwise the process of evolution would not have been directed towards the emergence of multicellular organisms and the world would still be inhabited exclusively by those whom we call "simple".
The main constructive difference between a unicellular and multicellular organism is that the organs of a multicellular organism are built from millions of individual cells, which, according to the principle of similarity and functional affinity, are combined into tissues, while the organelles of a unicellular organism are elements of a single cell.
What is the real advantage of a multicellular organism? In the ability to separate functions in space and time, as well as in the specialization of individual tissue and cellular structures to perform strictly defined functions. In fact, these differences are similar to the difference between the medieval subsistence economy and modern industrial production. The cell, which is an independent organism, is forced to solve all the problems that confront it, using the resources it has. A multicellular organism singles out for the solution of each of the functional tasks a special population of cells or a complex of such populations (tissue, organ, functional system) that are maximally adapted for solving this particular task. It is clear that the efficiency of problem solving by a multicellular organism is much higher. More precisely, a multicellular organism is much more likely to adapt to the wide range of situations it has to face. This implies a fundamental difference between a cell and a multicellular organism in the adaptation strategy: the first reacts holistically and in a generalized way to any environmental influence, the second is able to adapt to living conditions due to the restructuring of the functions of only some of its constituent parts - tissues and organs.
It is important to emphasize that the tissues of a multicellular organism are very diverse and each is best adapted to perform a small number of functions necessary for the life and adaptation of the whole organism. At the same time, the cells of each of the tissues are able to perfectly perform only one single function, and the entire diversity of the functional capabilities of the body is provided by the diversity of its constituent cells. For example, nerve cells are only able to produce and conduct an impulse of excitation, but they are not able to change their size or carry out the destruction of toxic substances. Muscle cells are able to conduct an impulse of excitation in the same way as nerve cells, but at the same time they themselves contract, ensuring the movement of body parts in space or changing the tension (tone) of the structures consisting of these cells. Liver cells are not able to conduct electrical impulses or contract - but their biochemical power ensures the neutralization of a huge number of harmful and toxic molecules that enter the bloodstream during the life of the body. Bone marrow cells are specially designed for the production of blood and cannot be occupied with anything else. Such a "division of labor" is a characteristic feature of any complexly organized system; social structures also function according to the same rules. This must be taken into account when predicting the results of any reorganizations: no specialized subsystem is able to change the nature of its functioning if its own structure does not change.
The emergence of tissues with qualitative characteristics in the process of ontogenesis is a relatively slow process, and it does not occur due to the fact that existing cells acquire new functions: almost always, new functions are provided by new generations of cellular structures that are formed under the control of the genetic apparatus and under the influence of external requirements. or internal environment.
Ontogeny is a striking phenomenon, during which a unicellular organism (zygote) turns into a multicellular organism, maintaining integrity and viability at all stages of this remarkable transformation and gradually increasing the diversity and reliability of the functions performed.
Structural-functional and systemic approaches to the study of the organism
Scientific physiology was born on the same day as anatomy - this happened in the middle of the 17th century, when the great English physician William Harvey received the permission of the church and the king and performed the first autopsy of a criminal sentenced to death after a thousand-year break in order to scientifically study the internal structure of the human body. Of course, even the ancient Egyptian priests, when embalming the bodies of their pharaohs, knew perfectly well the structure of the human body from the inside - but this knowledge was not scientific, it was empirical, and, moreover, secret: divulging any information about this was considered sacrilege and was punishable by death. The great Aristotle, teacher and mentor of Alexander the Great, who lived 3 centuries BC, had a very vague idea of how the body works and how it works, although he was encyclopedically educated and seemed to know everything that European civilization had accumulated by that time. More knowledgeable were the ancient Roman doctors - students and followers of Galen (2nd century AD), who laid the foundation for descriptive anatomy. Medieval Arab doctors gained great fame, but even the greatest of them - Ali Abu ibn Sina (in European transcription - Avicenna, XI century) - treated the human spirit rather than the body. And now W. Harvey, with a confluence of a huge number of people, conducts the first study in the history of European science of the structure of the human body. But Harvey was most interested in HOW the body WORKS. Since ancient times, people have known that a heart beats in the chest of each of us. Doctors at all times measured the pulse and assessed the state of health and the prospects for combating various diseases by its dynamics. Until now, one of the most important diagnostic techniques in the famous and mysterious Tibetan medicine is long-term continuous monitoring of the patient's pulse: the doctor sits at his bedside and keeps his finger on the pulse for hours, and then calls the diagnosis and prescribes treatment. It was well known to everyone: the heart stopped - life stopped. However, the Galen school, traditional at that time, did not connect the movement of blood through the vessels with the activity of the heart.
But before Harvey's eyes - a heart with tubes-vessels filled with blood. And Harvey understands that the heart is just a muscle bag that acts as a pump that pumps blood throughout the body, because vessels scatter throughout the body, which become more numerous and thinner as they move away from the pump. Through the same vessels, blood returns to the heart, making a complete revolution and continuously flowing to all organs, to every cell, carrying nutrients with it. Nothing is yet known about the role of oxygen, hemoglobin has not been discovered, doctors are in no way able to distinguish between proteins, fats and carbohydrates - in general, knowledge of chemistry and physics is still extremely primitive. But various technologies have already begun to develop, the engineering thought of mankind has invented many devices that facilitate production or create completely new, previously unprecedented technical possibilities. It becomes clear to Harvey's contemporaries that certain mechanisms , the structural basis of which is made up of separate organs, and each organ is designed to perform a particular function. The heart is a pump that pumps blood through the "veins", just like those pumps that supply water from lowland lakes to a manor on a hillock and feed fountains pleasing to the eye. Lungs are bellows through which air is pumped, as apprentices do in a forge, in order to heat iron more and make it easier to forge. Muscles are ropes attached to bones, and their tension causes these bones to move, which ensures the movement of the whole body, just as builders use hoists to lift huge stones to the upper floors of a temple under construction.
It is human nature to always compare new phenomena discovered by him with those already known, which have come into use. A person always builds analogies in order to make it easier to understand, to explain to himself the essence of what is happening. The high level of development of mechanics in the era when Harvey was conducting his research inevitably led to a mechanical interpretation of the numerous discoveries made by physicians - Harvey's followers. Thus, structural-functional physiology was born with its slogan: one organ - one function.
However, with the accumulation of knowledge - and this largely depended on the development of physical and chemical sciences, since it is they that supply the main methods for conducting scientific research in physiology - it became clear that many organs perform not one, but several functions. For example, the lungs - not only ensure the exchange of gases between the blood and the environment, but also participate in the regulation of body temperature. The skin, performing primarily the function of protection, is at the same time both an organ of thermoregulation and an organ of excretion. Muscles are able not only to actuate skeletal levers, but also, due to their contractions, to warm the blood flowing to them, maintaining temperature homeostasis. Examples of this kind can be given endlessly. The polyfunctionality of organs and physiological systems became especially clear in the late 19th and early 20th centuries. It is curious that at the same time, a wide variety of "universal" machines and tools appeared in technology, with a wide range of capabilities - sometimes, to the detriment of simplicity and reliability. This is an illustration of the fact that the technical thought of mankind and the level of scientific understanding of the organization of processes in wildlife develop in close interaction with each other.
By the middle of the 30s of the XX century. it became clear that even the concept of polyfunctionality of organs and systems is no longer able to explain the coherence of body functions in the process of adaptation to changing conditions or in the dynamics of age development. A new understanding of the meaning of the processes occurring in a living organism began to take shape, from which a systematic approach to the study of physiological processes was gradually formed. At the origins of this direction of physiological thought were outstanding Russian scientists - A.A. Ukhtomsky, N.A. Bernstein and P.K. Anokhin.
The most fundamental difference between the structural-functional and systemic approaches lies in the understanding of what is a physiological function. For structural-functional approach characteristic is the understanding of the physiological function as a certain process carried out by a certain (specific) set of organs and tissues, changing its activity in the course of functioning in accordance with the influence of control structures. In this interpretation, physiological mechanisms are those physical and chemical processes that underlie the physiological function and ensure the reliability of its performance. The physiological process is the object that is in the center of attention of the structural-functional approach.
Systems approach is based on the idea of expediency, i.e., under a function in the framework of a systematic approach, they understand the process of achieving a certain goal, result. At various stages of this process, the need for the involvement of certain structures can change quite significantly, therefore the constellation (composition and nature of the interaction of elements) of a functional system is very mobile and corresponds to the particular task that is being solved at the current moment. The presence of a goal implies that there is some model of the state of the system before and after achieving this goal, an action program, and there is also a feedback mechanism that allows the system to control its current state (intermediate result) in comparison with the simulated one and, on this basis, make adjustments to the action program in order to achieve the end result.
From the standpoint of the structural-functional approach, the environment acts as a source of stimuli for certain physiological reactions. A stimulus has arisen - in response, a reaction has arisen, which either fades as you get used to the stimulus, or stops when the stimulus ceases to act. In this sense, the structural-functional approach considers the organism as a closed system that has only certain channels of information exchange with the environment.
The systems approach considers the organism as an open system, the target function of which can be placed both inside and outside it. In accordance with this view, the body reacts to the influences of the external world as a whole, rebuilding the strategy and tactics of this response, depending on the results achieved, each time in such a way as to achieve model target results either faster or more reliably. From this point of view, the reaction to an external stimulus fades when the target function formed under its influence is realized. The stimulus may continue to act, or, on the contrary, it may cease to operate long before the completion of functional rearrangements, but once started, these rearrangements must go through the entire programmed path, and the reaction will end only when the feedback mechanisms bring information about the complete balance of the body with the environment. at a new level of functional activity. A simple and clear illustration of this situation can serve as a reaction to any physical load: to perform it, muscle contractions are activated, which necessitates a corresponding activation of blood circulation and respiration, and even when the load has already been completed, the physiological functions still retain their increased activity for quite a long time, since they provide alignment of metabolic states and normalization of homeostatic parameters. The functional system that ensures the performance of physical exercise includes not only the muscles and nervous structures that give the order to the muscles to contract, but also the circulatory system, the respiratory system, the endocrine glands and many other tissues and organs involved in this process, associated with serious changes. the internal environment of the body.
The structural-functional view of the essence of physiological processes reflected the deterministic, mechanistic-materialistic approach that was characteristic of all natural sciences in the 19th and early 20th centuries. The pinnacle of its development can probably be considered the theory of conditioned reflexes by I.P. Pavlov, with the help of which the great Russian physiologist tried to understand the mechanisms of brain activity by the same methods by which he successfully studied the mechanisms of gastric secretion.
The systems approach stands on stochastic, probabilistic positions and does not reject teleological (expedient) approaches characteristic of the development of physics and other natural sciences in the second half of the 20th century. It has already been mentioned above that physiologists, together with mathematicians, within the framework of this approach, came to the formulation of the most general cybernetic laws that all living things obey. Equally important for understanding physiological processes at the present level are the ideas about the thermodynamics of open systems, the development of which is associated with the names of outstanding physicists of the 20th century. Ilya Prigogine, von Bertalanffy and others.
The body as a whole system
The modern understanding of complex self-organizing systems includes the idea that they clearly define the channels and methods of information transmission. In this sense, a living organism is a quite typical self-organizing system.
The body receives information about the state of the surrounding world and the internal environment with the help of sensors-receptors that use a wide variety of physical and chemical design principles. So, for a person, the most important is the visual information that we receive with the help of our opto-chemical sensors - the eyes, which are both a complex optical device with an original and accurate guidance system (adaptation and accommodation), as well as a physico-chemical converter of photon energy into electrical impulse of the optic nerves. Acoustic information comes to us through a bizarre and finely tuned auditory mechanism that converts the mechanical energy of air vibrations into electrical impulses of the auditory nerve. Temperature sensors are no less finely arranged, tactile (tactile), gravitational (sense of balance). Olfactory and gustatory receptors are considered to be the most evolutionarily ancient, having a huge selective sensitivity in relation to some molecules. All this information about the state of the external environment and its changes enters the central nervous system, which performs several roles simultaneously - a database and knowledge base, an expert system, a central processor, as well as the functions of operational and long-term memory. Information from receptors located inside our body also flows there and transmits information about the state of biochemical processes, about the tension in the work of certain physiological systems, about the actual needs of individual groups of cells and tissues of the body. In particular, there are sensors for pressure, carbon dioxide and oxygen content, acidity of various biological fluids, tension of individual muscles, and many others. Information from all these receptors is also sent to the center. Sorting of information coming from the periphery begins already at the stage of its reception - after all, the nerve endings of various receptors reach the central nervous system at its different levels, and, accordingly, information enters various parts of the central nervous system. However, all of it can be used in the decision-making process.
The decision must be made when the situation has changed for some reason and requires appropriate responses at the system level. For example, a person is hungry - this is reported to the "center" by sensors that register an increase in fasting secretion of gastric juice and peristalsis of the gastrointestinal tract, as well as sensors that register a decrease in blood glucose levels. In response, the peristalsis of the gastrointestinal tract increases reflexively and the secretion of gastric juice increases. The stomach is ready to receive a new portion of food. At the same time, optical sensors make it possible to see food products on the table, and a comparison of these images with models stored in the database of long-term memory suggests that there is an opportunity to satisfy hunger remarkably, while enjoying the look and taste of the food consumed. In this case, the central nervous system instructs the executive (effector) organs to take the necessary actions that will ultimately lead to saturation and elimination of the original cause of all these events. Thus, the goal of the system is to eliminate the cause of the disturbance by its actions. This goal is achieved in this case relatively easily: it is enough to reach out to the table, take the food lying there and eat it. However, it is clear that according to the same scheme, an arbitrarily complex scenario of actions can be constructed.
Hunger, love, family values, friendship, shelter, self-affirmation, craving for new things and love for beauty - this short list almost exhausts the motives for action. Sometimes they are overgrown with a huge number of incoming psychological and social complexities, closely intertwined with each other, but in the most basic form they remain the same, forcing a person to perform actions, whether in the time of Apuleius, Shakespeare or in our time.
Act - what does it mean in terms of systems? This means that the central processor, obeying the program embedded in it, taking into account all possible circumstances, makes a decision, i.e. builds a model of the required future and develops an algorithm for achieving this future. On the basis of this algorithm, orders are given to individual effector (executive) structures, and almost always they contain muscles, and in the process of fulfilling the order of the center, the body or its parts move in space.
And once the movement is carried out, it means that physical work is performed in the field of terrestrial gravity, and, consequently, energy is spent. Of course, the operation of the sensors and the processor also requires energy, but the energy flow increases many times when muscle contractions are turned on. Therefore, the system must take care of an adequate supply of energy, for which it is necessary to increase the activity of blood circulation, respiration and some other functions, as well as to mobilize the available reserves of nutrients.
Any increase in metabolic activity entails a violation of the constancy of the internal environment. This means that the physiological mechanisms of maintaining homeostasis should be activated, which, by the way, also need significant amounts of energy for their activity.
Being a complexly organized system, the body has not one, but several circuits of regulation. The nervous system is probably the main, but by no means the only regulatory mechanism. Very important role perform endocrine organs - endocrine glands, which chemically regulate the activity of almost all organs and tissues. In addition, each cell of the body has its own internal system self-regulation.
It should be emphasized that an organism is an open system not only from a thermodynamic point of view, i.e., it exchanges with the environment not only energy, but also matter and information. We consume matter mainly in the form of oxygen, food and water, and we excrete it in the form of carbon dioxide, feces and sweat. As for information, each person is a source of visual (gestures, postures, movements), acoustic (speech, noise from movement), tactile (touch) and chemical (numerous smells that our pets perfectly distinguish) information.
Another important feature of the system is the finiteness of its dimensions. The organism is not smeared over the environment, but has a certain shape and is compact. The body is surrounded by a shell, a boundary that separates the internal environment from the external. The skin, which performs this role in the human body, is an important element of its design, since it is in it that many sensors are concentrated that carry information about the state of the outside world, as well as ducts for removing metabolic products and information molecules from the body. The presence of clearly defined boundaries turns a person into an individual who feels his separation from the surrounding world, his uniqueness and uniqueness. This is a psychological effect that occurs on the basis of the anatomical and physiological structure of the body.
The main structural and functional blocks that make up the body
Thus, the following can be attributed to the main structural and functional blocks that make up the body (each block includes several anatomical structures with many functions):
sensors (receptors) that carry information about the state of the external and internal environment;
central processor and control unit, including nervous and humoral regulation;
effector organs (primarily the musculoskeletal system), which ensure the execution of the orders of the "center";
an energy block that provides effector and all other structural components with the necessary substrate and energy;
a homeostatic block that maintains the parameters of the internal environment at the level necessary for life;
a shell that performs the functions of a border zone, reconnaissance, protection and all types of exchange with the environment.
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ESSAY
AGE PHYSIOLOGY
age physiology is a science that studies the features of the life process of an organism at different stages of ontogenesis.
It is an independent branch of human and animal physiology, the subject of which is the study of the patterns of formation and development of the physiological functions of the body throughout its life path from fertilization to the end of life.
Depending on what age period the age-related physiology studies, there are: age-related neurophysiology, age-related endocrinology, age-related physiology of muscle activity and motor function; age-related physiology of metabolic processes, cardiovascular and respiratory systems, digestive and excretory systems, physiology of embryonic development, physiology of infants, physiology of children and adolescents, physiology of adulthood, gerontology (the science of aging).
The main objectives of the study of age physiology are as follows:
study of the features of the functioning of various organs, systems and the body as a whole;
identification of exogenous and endogenous factors that determine the features of the functioning of the body in different age periods;
determination of objective age criteria (age standards);
establishing patterns of individual development.
Developmental physiology is closely related to many branches of physiological science and makes extensive use of data from many other biological sciences. Thus, in order to understand the patterns of formation of functions in the process of individual human development, data from such physiological sciences as cell physiology, comparative and evolutionary physiology, the physiology of individual organs and systems: the heart, liver, kidneys, blood, respiration, nervous system, etc. are needed.
At the same time, the patterns and laws discovered by age physiology are based on data from various biological sciences: embryology, genetics, anatomy, cytology, histology, biophysics, biochemistry, etc. Finally, age physiology data, in turn, can be used to develop various scientific disciplines. For example, age physiology is important for the development of pediatrics, pediatric traumatology and surgery, anthropology and gerontology, hygiene, developmental psychology and pedagogy.
History and main stages of development of age physiology
The scientific study of the age characteristics of the child's body began relatively recently - in the second half of the 19th century. Shortly after the discovery of the law of conservation of energy, physiologists discovered that a child consumes slightly less energy during the day than an adult, although the size of a child's body is much smaller. This fact required a rational explanation. In search of this explanation, the German physiologist Max Rubner conducted a study of the rate of energy metabolism in dogs of different sizes and found that larger animals per 1 kg of body weight consume much less energy than small ones. Having calculated the surface area of the body, Rubner made sure that the ratio of the amount of energy consumed is proportional to the size of the body surface - and this is not surprising: after all, all the energy consumed by the body must be released into the environment in the form of heat, i.e. the energy flux depends on the heat transfer surface. It was the differences in the ratio of mass and body surface that Rubner explained the difference in the intensity of energy metabolism between large and small animals, and at the same time between adults and children. Rubner's "surface rule" was one of the first fundamental generalizations in developmental and environmental physiology. This rule explained not only the differences in the magnitude of heat production, but also in the frequency of heart contractions and respiratory cycles, pulmonary ventilation and volume of blood flow, as well as in other indicators of the activity of autonomic functions. In all these cases, the intensity of physiological processes in a child's body is significantly higher than in an adult's body. Such a purely quantitative approach is characteristic of the German physiological school of the 19th century, consecrated by the names of outstanding physiologists. E.F. Pfluger, G.L. Helmholtz and others. Through their labors, physiology was raised to the level of the natural sciences, standing on a par with physics and chemistry. However, the Russian physiological school, although rooted in the German one, has always been distinguished by an increased interest in qualitative features and regularities. An outstanding representative of the Russian pediatric school, Dr. Nikolai Petrovich Gundobin even at the very beginning of the 20th century. argued that the child is not just small, he is also in many ways not the same as an adult. His body is arranged and works differently, and at each stage of its development, the child's body is perfectly adapted to the specific conditions that it has to face in life. real life. and ideas were shared and developed by a remarkable Russian physiologist, teacher and hygienist Pyotr Frantsevich Lesgaft, laid the foundations of school hygiene and physical education of children and adolescents. He considered it necessary to deeply study the child's body, its physiological capabilities.
The central problem of developmental physiology was most clearly formulated in the 20s of the XX century. German physician and physiologist E. Helmreich. He argued that the differences between an adult and a child are in two planes, which must be considered as independently as possible, as two independent aspects: the child as small organism and child developing organism. In this sense, Rubner's "surface rule" considers the child in only one aspect - namely, as a small organism. Much more interesting are those features of the child that characterize him as a developing organism. One of these fundamental features is the discovery at the end of the 30s Ilya Arkadyevich Arshavsky uneven development of sympathetic and parasympathetic influences of the nervous system on all the most important functions of the child's body. I.A. Arshavsky proved that sympathotonic mechanisms mature much earlier, and this creates an important qualitative originality of the functional state of the child's body. The sympathetic division of the autonomic nervous system stimulates the activity of the cardiovascular and respiratory systems, as well as metabolic processes in the body. Such stimulation is quite adequate for an early age, when the body needs an increased intensity of metabolic processes necessary to ensure the processes of growth and development. As the child's body matures, parasympathetic, inhibitory influences intensify. As a result, the pulse rate, respiratory rate, and the relative intensity of energy production decrease. The problem of uneven heterochrony (time difference) in the development of organs and systems has become the central object of research by the outstanding physiologist academician Peter Kuzmich Anokhin and his scientific school. In the 1940s he formulated the concept systemogenesis, according to which the sequence of events unfolding in the body is built in such a way as to satisfy the changing needs of the body in the course of development. At the same time, P.K. Anokhin for the first time moved from consideration of anatomically integral systems to the study and analysis of functional relationships in the body. Another outstanding physiologist Nikolai Alexandrovich Bernshtein showed how algorithms for controlling voluntary movements gradually form and become more complex in ontogenesis, how the mechanisms of higher movement control spread with age from the most evolutionarily ancient subcortical structures of the brain to newer ones, reaching an ever higher level of "building movements". In the works of N.A. Bernshtein, it was shown for the first time that the direction of ontogenetic progress in the control of physiological functions clearly coincides with the direction of phylogenetic progress. Thus, on the basis of physiological material, the concept of E. Haeckel and A.N. Severtsov that individual development (ontogenesis) is an accelerated evolutionary development (phylogenesis) was confirmed.
The largest specialist in the field of the theory of evolution academician Ivan Ivanovich Schmalhausen For many years he also dealt with questions of ontogeny. The material on which I.I. Shmalgauzen drew his conclusions rarely had a direct bearing on the physiology of development, but the conclusions from his works on the alternation of stages of growth and differentiation, as well as methodological work in the field of studying the dynamics of growth processes, carried out in the 30s , and are still of great importance for understanding the most important patterns of age-related development. In the 1960s, the physiologist Hakob Artashesovich Markosyan put forward the concept of biological reliability as one of the factors of ontogeny. She relied on numerous facts that testified that the reliability of functional systems increases significantly as the body grows older. This was confirmed by data on the development of the blood coagulation system, immunity, and the functional organization of brain activity. In recent decades, many new facts have accumulated that confirm the main provisions of the concept of biological reliability of A.A. Markosyan. At the present stage of development of biomedical science, research in the field of age-related physiology is also continuing, already using modern research methods. Thus, physiological science currently has at its disposal considerable multifaceted information concerning the functional activity of any physiological system of the child's organism and its activity as a whole.
The main patterns of growth in the development of children and adolescents.
The main feature of childhood and adolescence- a constantly ongoing process of growth and development, during which the gradual formation of an adult is carried out. During this process, the quantitative indicators of the body increase (the size of individual organs and the whole body), and there is also an improvement in the work of organs and physiological systems that ensure the possibility of normal life of a mature person, the main points of which are labor activity and the birth of healthy offspring. How a child and adolescent grows and develops largely determines his future and, therefore, this process from the moment the child is born to the completion of the growth and development processes should be under the constant control of doctors, parents and teachers. While each child is completely different, some patterns of growth and development of children are common to all. The development of a child is a non-stop process in which all stages of slow quantitative changes gradually lead to dramatic transformations in the structures and functions of the child's body. Quite often such changes have a sharp spasmodic form. The normal course of growth and development of a child and adolescent indicates a favorable state of his body, the absence of pronounced harmful influences, and therefore physical development at this age is one of the leading signs of health, on which other indicators depend. The level of achieved physical development is necessarily assessed by a doctor during a medical examination and is a necessary criterion for an overall assessment of the health status of a child and adolescent. The number of indicators that determine the physical development of a person is quite large. For the purposes of medical and pedagogical practice, relatively easy-to-measure indicators called somatometric indicators are most often used: body length, body weight, chest circumference. External examination of the body reveals somatoscopic indicators: the shape of the chest, back, feet, posture, muscle condition, fat deposition, skin elasticity, signs of puberty. To assess the functional capabilities of the body, physiometric indicators are used - the vital capacity of the lungs (VC), the force of compression of the hand (dynamometry). All these indicators are taken into account when assessing physical development of children and adolescents, which should be carried out comprehensively, using all of these indicators. For a correct assessment of the physical development of a child, it is necessary to know the basic patterns of development of children and adolescents and the age-related features of the course of this process, which allows us to understand and explain the activity of individual organs and systems, their relationship, the functioning of the whole organism of the child in different age periods and its unity with the external environment.
The human life cycle is conditionally divided into three stages: maturation, mature age and aging. It is possible to draw a chronological boundary for the transition of an organism from one stage to another on the basis of studying the characteristics of its growth and development, interaction with the environment (including social) environment. The stage of maturation is characterized, first of all, by the achievement of puberty, the ability of the organism and the ability to perform the reproductive function, which ensures the preservation of the species. The biological meaning of the individual growth and development of any living being, including humans, lies in the preservation of the species. However, it would be a mistake to judge a person's maturity only by the degree of sexual development. An equally important sign is the readiness of the individual to carry out social functions, labor and creative activity, and this is the social and social meaning of his development. Puberty occurs at 13-15 years of age. Labor maturity comes much later, usually by the end of school or vocational school, that is, at 17-18 years old. It comes only with the approach to the completion of physical development and the acquisition of experience in social and social activity. Currently, there is a discrepancy in the time of onset of sexual and labor maturity. If puberty in modern conditions is observed somewhat earlier, then labor maturity in the conditions of modern production, which requires a fairly high level of training, on the contrary, is later. Therefore, the chronological boundary of the full maturation of the body and the onset of maturity should be considered 20-21 years. Namely, by this age, not only the process of full maturation and growth is completed, but the necessary knowledge is accumulated, moral foundations are formed, that is, opportunities are created for a person to perform both biological and social functions. At the entire stage of maturation (from the moment of birth to full maturity), the growth and development of the organism proceed in accordance with objectively existing laws, the main of which are:
uneven pace of growth and development,
non-simultaneous growth and development of individual organs and systems (heterochronism),
conditionality of growth and development by sex (sexual dimorphism),
genetic conditioning of growth and development,
conditionality of growth and development by factors habitat children,
historical development trends (acceleration, deceleration).
Uneven rate of growth and development. The processes of growth and development proceed continuously, are progressive in nature, but their rate has a non-linear dependence on age. The younger the body, the more intense the processes of growth and development. This is most clearly reflected in the indicators of daily energy consumption. The child is 1-3 months old. daily energy consumption per 1 kg of body weight per day is 110-120 kcal, for a one-year-old - 90-100 kcal. In subsequent periods of a child's life, the decrease in the relative daily energy expenditure continues. Changes in the body length of children and adolescents testify to the uneven growth and development. During the first year of life, the length of the body of a newborn increases by 47%, during the second - by 13%, during the third - by 9%. At the age of 4-7 years, body length increases annually by 5-7%, and at the age of 8-10 years - only by 3%.
During puberty, a growth spurt is noted, at the age of 16-17 years, a decrease in the rate of its growth is observed, and at 18-20 years, the increase in body length practically stops. Changes in body weight, chest circumference, as well as the development of individual organs and systems as a whole occur unevenly. The unevenness of the rate of growth and development of the organism at the stage of maturation is a general pattern. However, during this period, some individual characteristics also appear. There are individuals whose rate of development is accelerated, and in terms of maturity they are ahead of their chronological (calendar) age. The reverse relationship is also possible. In this regard, the term "child's age" should be specified: chronological or biological. The difference between chronological and biological age can be up to 5 years. Children with a slow rate of biological development can be 10-20%. Such children are most often identified before entering school or during training. The lag of biological age in children is manifested by a decrease in most indicators of physical development compared to average age and is combined with more frequent deviations in the musculoskeletal system, nervous and cardiovascular systems. Schoolchildren with a slow rate of biological development are less active in the classroom. They have increased distractibility and an unfavorable type of change in performance. During the educational process, a more pronounced tension of the visual, motor analyzer and the cardiovascular system is revealed. The most pronounced changes in working capacity and health status are observed in children with a sharp lag in biological age (a difference of 3 years or more). accelerated pace individual development of the child leads to advance of biological age in comparison with chronological. "Advanced" development is less common in groups of students than "lagging behind". Accelerated development is observed more often in girls. In schoolchildren with an accelerated pace of individual development, the working capacity is lower than in children whose biological age corresponds to the calendar one. Among them, there are more people suffering from hypertension and chronic tonsillitis, they have higher morbidity rates, more often and sharper manifestations of functional abnormalities. The highest frequency of deviations from biological age is found among adolescents.
Thus, individual deviations in the rate of growth and development of the child from the average age cause a discrepancy between the biological age and the chronological one, which, both in the case of advance and especially lagging, require attention from doctors and parents. Criteria of biological age: the level of ossification of the skeleton, the timing of eruption and change of teeth, the appearance of secondary sexual characteristics, the onset of menstruation, as well as morphological indicators of physical development (body length and its annual increase). With age, the degree of information content of indicators of biological age changes. From 6 to 12 years of age, the main indicators of development are the number of permanent teeth (“dental age”) and body length. Between 11 and 15 years, the most informative indicators of the annual increase in body length, as well as the severity of secondary sexual characteristics and the age of menstruation in girls. At the age of 15 and later important indicator development becomes the appearance of secondary sexual characteristics, and indicators of body length and development of teeth lose their information content. The level of ossification of the skeleton is determined using X-ray studies only if there are special medical indications - with pronounced developmental disorders. Non-simultaneous growth and development of individual organs and systems (heterochronism). The processes of growth and development proceed unevenly. Each age is characterized by certain morphofunctional features. The child's body is considered as a whole, but the growth and development of its individual organs and systems occur non-simultaneously (heterochronously). Selective and accelerated maturation is ensured by those structural formations and functions that determine the survival of the organism. In the first years of a child's life, the mass of the brain and spinal cord mainly increases, which cannot be considered accidental: there is an intensive formation of the functional systems of the body. Through the nervous system, the organism is connected with the external environment: mechanisms of adaptation to constantly changing conditions are formed, optimal conditions are created for receiving information and performing integrative actions. In contrast, the lymphatic tissue does not develop in the first years of life, its growth and formation occur at the age of 10-12 years. Only after 12 years there is an intensive development of the genital organs and the formation of the reproductive function. The growth rates of individual parts of the body are also different. In the process of growth, the proportions of the body change, and the child from a relatively large-headed, short-legged and long-bodied gradually turns into a small-headed, long-legged and short-bodied child. Thus, intensive development and the final formation of individual organs and systems do not occur in parallel. There is a certain sequence of growth and development of certain structural formations and functions. At the same time, during the period of intensive growth and development of a functional system, its increased sensitivity to the action of specific factors is observed. During the period of intensive development of the brain, an increased sensitivity of the body to a lack of squirrel in food; in the period of development of speech motor functions - to speech communication; during the development of motor skills - to motor activity. The ability of the child's body to specific activities, its resistance to various environmental factors are determined by the level of maturation of the corresponding functional systems. Thus, the associative sections of the cerebral cortex, which ensure its integral function and readiness for schooling, mature gradually in the course of the individual development of the child by the age of 6-7. In this regard, the forced education of children at an early age may affect their subsequent development. The system that transports oxygen to the tissues also develops gradually and reaches maturity by the age of 16-17. Given this, hygienists prescribe the restriction of physical activity for children. Only in adolescence, upon reaching the morphological and functional maturity of the cardiovascular and respiratory systems, long-term performance of large physical exertion and the development of endurance are allowed. Thus, functional readiness for certain types of educational, labor and sports activities is formed non-simultaneously, therefore, both types of activities and the impact of environmental factors on various analyzers or functional systems should be normalized differentially. The hygienic norm throughout the entire stage of maturation of the organism changes in accordance with the change in age-related sensitivity to the action of the factor. The heterochrony of the growth and development of individual organs and systems is the scientific basis for the differentiated regulation of environmental factors and the activities of children and adolescents.
Conditionality of growth and development by sex (sexual dimorphism).
Sexual dimorphism is manifested in the features of the metabolic process, the rate of growth and development of individual functional systems and the organism as a whole. So, boys before the onset of puberty have higher anthropometric indicators. During puberty, this ratio changes: girls in terms of length and body weight, chest circumference surpass their peers. There is a crossover of the age curves of these indicators. At the age of 15, the intensity of growth in boys increases, and boys, in terms of their anthropometric indicators, are again ahead of girls. A second intersection of curves is formed. This double crossing of the curves of age-related changes in indicators of physical development is characteristic of normal physical development. At the same time, there is an uneven rate of development of many functional systems, especially muscular, respiratory and cardiovascular. For example, the strength of the hand or muscles - the extensors of the back in boys of all ages is higher than that of their peers. Differences exist not only in physical performance, but also in psychophysiological indicators. age physiology organism child
And so, along with common to both sexes growth patterns of children and adolescents there are differences in the rate, timing and rates of growth and development of boys and girls. Sexual dimorphism is taken into account when normalizing physical activity, organizing the educational process. Gender differences in the growth and development of the body are important in the professional orientation of schoolchildren, sports selection and training of young athletes. Domestic hygienic science develops the concept of correspondence, first of all, of training loads to the functional capabilities of a growing organism and the expediency of its training in order to protect and promote health. In accordance with this, activity standards are being developed in our country on the basis of the age-sex principle and recommendations are given for the reasonable training of a growing organism in order to increase its reserve abilities and make fuller use of the body's physical capabilities inherent in nature.
Inside the uterineuhstages of development.
In the intrauterine development of a person, three periods are conventionally distinguished:
1 The implantation period lasts from the moment of fertilization to 2 weeks. This period is characterized by a rapid systematic crushing of a fertilized egg, its advancement along the fallopian tube to the uterine cavity; implantation (attachment of the embryo and introduction into the uterine mucosa) on the 6-7th day after fertilization and further formation of the fetal membranes, creating the necessary conditions for the development of the embryo. They provide nutrition (trophoblast), create a liquid habitat and mechanical protection (fluid of the amniotic sac).
2 The embryonic period lasts from the 3rd to the 10-12th week of pregnancy. During this period, the rudiments of all the most important organs and systems of the future baby are formed, the torso, head, limbs are formed. The placenta is developing - the most important organ of pregnancy, separating two blood flows (mother and fetus) and providing metabolism between mother and fetus, protecting it from infectious and other harmful factors, from the mother's immune system. At the end of this period, the embryo becomes a fetus with a baby-like configuration.
3 The fetal period begins from the 3rd month of pregnancy and ends with the birth of a child. Nutrition and metabolism of the fetus is carried out through the placenta. There is a rapid growth of the fetus, the formation of tissues, the development of organs and systems from their rudiments, the formation and formation of new functional systems that ensure the life of the fetus in the womb and the child after birth.
After the 28th week of pregnancy, the fetus begins to form a supply of valuable substances that are necessary in the first time after birth - calcium, iron, copper, vitamin B12, etc. There is a maturation of the surfactant, which ensures normal lung function. Prenatal development is influenced by various environmental factors. They have the most significant effect on the organs that develop most intensively at the time of exposure.
postnatal period
The postnatal period is the stage of ontogenesis, during which the growing organism begins to adapt to the influence of the external environment.
The postnatal period goes through three periods of development:
1. Juvenile (before puberty)
2. Mature (or puberty, adult sexually mature state)
3. Sinilny (old age) periods.
In humans, the postnatal period is conditionally divided into 12 periods (age periodization):
1. Newborns - from birth to 10 days
2. Breast age - from 10 days to 1 year
3. Early childhood - from 1 year to 3 years
4. The first childhood - from 4 years to 7 years
5. Second childhood - 8 - 12 years old (boys), 8 - 11 years old (girls)
6. Adolescence - 13 - 16 years old (boys), 12 - 15 years old (girls)
7. Youth period - 17 - 18 years old (boys), 16 - 18 years old (girls)
8. Mature age, I period: 19 - 35 years old (men), 19 - 35 years old (women)
9. Mature age, II period: 36 - 60 years (men), 36 - 55 years (women)
10. Old age - 61 - 74 years (men), 56 - 74 years (women)
11. Senile age 75 - 90 years (men and women)
12. Long-livers - 90 years and older.
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Age physiology: (Physiology of child development)
Tutorial
For students of higher pedagogical educational institutions
Reviewers:
doctor of biological sciences, head. Department of Higher Nervous Activity and Psychophysiology of St. Petersburg University, Academician of the Russian Academy of Education, Professor A.S. Batuev;
Doctor of Biological Sciences, Professor I.A. Kornienko
FOREWORD
Elucidation of the patterns of child development, the specifics of the functioning of physiological systems at different stages of ontogenesis and the mechanisms that determine this specifics, is a necessary condition for ensuring the normal physical and mental development of the younger generation.
The main questions that parents, educators and psychologists should have in the process of raising and educating a child at home, in kindergarten or at school, at a consultative appointment or individual lessons, are what kind of child he is, what are his features, what option of training with him will be the most effective. Answering these questions is not at all easy, because this requires deep knowledge about the child, the patterns of his development, age and individual characteristics. This knowledge is also extremely important for developing the psychophysiological foundations for organizing educational work, developing mechanisms for adaptation in a child, determining the impact of innovative technologies on him, etc.
Perhaps, for the first time, the importance of a comprehensive knowledge of physiology and psychology for a teacher and educator was highlighted by the famous Russian teacher K.D. Ushinsky in his work "Man as an object of education" (1876). “The art of education,” wrote K.D. Ushinsky, - has the peculiarity that it seems familiar and understandable to almost everyone, and even an easy matter to others - and the more understandable and easier it seems, the less a person is familiar with it theoretically and practically. Almost everyone admits that parenting requires patience; some think that it requires an innate ability and skill, that is, a habit; but very few have come to the conclusion that, in addition to patience, innate ability and skill, special knowledge is also needed, although our numerous wanderings could convince everyone of this. It was K.D. Ushinsky showed that physiology is one of those sciences in which "facts are stated, compared and grouped, and those correlations of facts in which the properties of the object of education, i.e., a person, are found." Analyzing the physiological knowledge that was known, and this was the time of the formation of age physiology, K.D. Ushinsky emphasized: “From this source, which is just opening up, education has almost not yet scooped.” Unfortunately, even now we cannot talk about the wide use of age-related physiology data in pedagogical science. The uniformity of programs, methods, textbooks is a thing of the past, but the teacher still does not take into account the age and individual characteristics of the child in the learning process.
At the same time, the pedagogical effectiveness of the learning process largely depends on how the forms and methods of pedagogical influence are adequate to the age-related physiological and psychophysiological characteristics of schoolchildren, whether the conditions for organizing the educational process correspond to the capabilities of children and adolescents, whether the psychophysiological patterns of the formation of basic school skills - writing and reading, as well as basic motor skills in the process of classes.
The physiology and psychophysiology of a child is a necessary component of the knowledge of any specialist working with children - a psychologist, educator, teacher, social pedagogue. “Upbringing and education deals with a holistic child, with his holistic activity,” said the well-known Russian psychologist and teacher V.V. Davydov. - This activity, considered as a special object of study, contains in its unity many aspects, including ... physiological "(V.V. Davydov" Problems of developmental education. - M., 1986. - P. 167).
age physiology- the science of the features of the life of the body, the functions of its individual systems, the processes occurring in them, and the mechanisms of their regulation at different stages of individual development. Part of it is the study of the physiology of the child in different age periods.
A textbook on age-related physiology for students of pedagogical universities contains knowledge about human development at those stages when the influence of one of the leading factors of development - education - is most significant.
The subject of developmental physiology (physiology of child development) as an academic discipline is the features of the development of physiological functions, their formation and regulation, the vital activity of the organism and the mechanisms of its adaptation to the external environment at different stages of ontogenesis.
Basic concepts of age physiology:
organism - the most complex, hierarchically (subordinately) organized system of organs and structures that ensure vital activity and interaction with the environment. The basic unit of an organism is cell . A collection of cells that are similar in origin, structure and function forms the cloth . Tissues form organs that perform specific functions. Function - specific activity organ or system.
Physiological system - a set of organs and tissues related by a common function.
Functional system - dynamic association of various organs or their elements, whose activities are aimed at achieving a specific goal (beneficial result).
As for the structure of the proposed textbook, it is built in such a way that students have a clear idea of the patterns of development of the body in the process of ontogenesis, the features of each age stage.
We tried not to overload the presentation with anatomical data and at the same time considered it necessary to give basic ideas about the structure of organs and systems at different stages of age development, which is necessary for understanding the physiological patterns of organization and regulation of physiological functions.
The book consists of four sections. Section I - "Introduction to developmental physiology" - reveals the subject of developmental physiology as an integral part of developmental physiology, gives an idea of the most important modern physiological theories of ontogenesis, introduces basic concepts, without which it is impossible to understand the main content of the textbook. In the same section, the most general idea about the structure of the human body and its functions.
Section II - "The Organism and the Environment" - gives an idea of the main stages and patterns of growth and development, the most important functions of the body that ensure the interaction of the body with the environment and its adaptation to changing conditions, the age development of the body and characteristic features stages of individual development.
Section III - "The Organism as a Whole" - contains a description of the activities of systems that integrate the body into a single whole. First of all, it is the central nervous system, as well as the autonomic nervous system and the system of humoral regulation of functions. The main patterns of age-related development of the brain and its integrative activity are the key aspect of the content of this section.
Section IV - "Stages of Child Development" - contains a morphophysiological description of the main stages of child development from birth to adolescence. This section is most important for practitioners who work directly with the child, for whom it is important to know and understand the basic morphological and functional age-related characteristics of the child's body at each stage of its development. To understand the contents of this section, it is necessary to master all the material presented in the previous three. This section concludes with a chapter that discusses the impact social factors on the development of the child.
At the end of each chapter, there are questions for independent work of students, which allow you to refresh the memory of the main provisions of the studied material that require special attention.
INTRODUCTION TO AGE PHYSIOLOGY
Chapter 1
The relationship of age physiology with other sciences
By the time of birth, the child's body is still very far from a mature state. A human cub is born small, helpless, it cannot survive without the care and care of adults. It takes a long time for it to grow and become a full-fledged mature organism.
