Current page: 1 (total book has 12 pages) [accessible reading excerpt: 8 pages]

Yuri Savchenkov, Olga Soldatova, Sergey 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. 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-related physiology is an additional educational material on the physiological characteristics of children of different ages, which is necessary for assimilation by students who study at 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 a brief description of the main directions of the ontogeny of indicators of a particular physiological system. In this version of the manual, the sections "Age characteristics of higher nervous activity and mental functions", "Age characteristics of endocrine functions", "Age characteristics of thermoregulation and metabolism" are significantly expanded.

This book contains descriptions of numerous physiological and biochemical indicators and will be useful in the practical work of not only future teachers, speech pathologists, child psychologists, but also future pediatricians, as well as young specialists and high school students who are already working, who want to replenish their knowledge about 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 not into a visual, but into an auditory neuron.

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, turning 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 this 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 of 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 beginning 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 secondary schools according to 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 developmental age, 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 average age of an organized group of children, it is customary to consider the age of a child 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 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 famous 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.

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 its physiological systems at different stages of ontogenesis for the protection of health 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 organism in different age periods is determined by two major factors: the morphological and functional maturity of physiological systems and the adequacy of the influencing environmental factors to the functional capabilities of the organism.

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 working organs, it is possible to compare information about 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 the systemic support of adaptive responses is the hierarchical nature 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 links 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 determine the approaches to the periodization of 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 you know, 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, the following periods are distinguished in the human life cycle until reaching adulthood: 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 the 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 both to indicators characterizing the age-related characteristics of each physiological system separately, and to indicators of the integral functioning of the body. All of the above requires an 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 maladjustment.

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 conditions for the development of 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 property 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 (II 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 provide 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, 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 the 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 can continue to operate or, on the contrary, it can stop its action 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 said above that physiologists, along with mathematicians, within the framework of this approach, came to the formulation of the most general cybernetic laws to which all living things are subject. 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 environment 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 physiological mechanisms for 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. A very important role is played by 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 of 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 main structural and functional blocks that make up the body include the following (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.

..

Short description:

Sazonov V.F. Age anatomy and physiology (a manual for OZO) [Electronic resource] // Kinesiologist, 2009-2018: [website]. Date of update: 01/17/2018..__.201_).

Attention! This material is in the process of regular updating and improvement. Therefore, we apologize for possible minor deviations from the curricula of previous years.

1. General information about the structure of the human body. Organ systems

Man, with his anatomical structure, physiological and mental characteristics, represents the highest stage in the evolution of the organic world. Accordingly, it has the most evolutionarily developed organs and organ systems.

Anatomy studies the structure of the body and its individual parts and organs. Knowledge of anatomy is necessary for the study of physiology, so the study of anatomy must precede the study of physiology.

Anatomy is a science that studies the structure of the body and its parts at the supracellular level in statics.

Physiology is a science that studies the processes of vital activity of an organism and its parts in dynamics.

Physiology studies the course of life processes at the level of the whole organism, individual organs and organ systems, as well as at the level of individual cells and molecules. At the present stage of the development of physiology, it is again united with the sciences that once separated from it: biochemistry, molecular biology, cytology and histology..

Differences Between Anatomy and Physiology

Anatomy describes the structures (structure) of the body in static condition.

Physiology describes the processes and phenomena of the body in dynamics (i.e. in motion, in change).

Terminology

Anatomy and physiology use common terms to describe the structure and operation of the body. Most of them are of Latin or Greek origin.

Basic terms ():

Dorsal(dorsal) - located on the dorsal side.

Ventral- located on the ventral side.

Lateral- located on the side.

Medial- located in the middle, occupying a central position. Remember the median from math? She is also in the middle.

Distal- remote from the center of the body. Do you know the word "distance"? One root.

Proximal- close to the center of the body.

Video:The structure of the human body

Cells and tissues

Characteristic of any organism is a certain organization of its structures.
In the process of evolution of multicellular organisms, cell differentiation occurred, i.e. cells of various sizes, shapes, structures and functions appeared. From identically differentiated cells, tissues are formed, the characteristic property of which is structural association, morphological and functional commonality and interaction of cells. Different fabrics are specialized in function. So, a characteristic property of muscle tissue is contractility; nervous tissue - transmission of excitation, etc.

Cytology studies the structure of cells. Histology - the structure of tissues.

Organs

Several tissues combined into a certain complex form an organ (kidney, eye, stomach, etc.). An organ is a part of the body that occupies a permanent position in it, has a certain structure and shape, and performs one or more functions.

The organ consists of several types of tissues, but one of them prevails and determines its main, leading function. In a muscle, for example, this tissue is muscle.

Organs are the working apparatus of the body, specialized to perform complex activities necessary for the existence of a holistic organism. The heart, for example, acts as a pump that pumps blood from the veins to the arteries; kidneys - the function of excreting end products of metabolism and water from the body; bone marrow - the function of hematopoiesis, etc. There are many organs in the human body, but each of them is part of a whole organism.

Organ systems
Several organs that perform a specific function together form an organ system.

Organ systems are anatomical and functional associations of several organs involved in the performance of any complex activity.

Organ systems:
1. Digestive (oral cavity, esophagus, stomach, duodenum, small intestine, large intestine, rectum, digestive glands).
2. Respiratory (lungs, airways - mouth, larynx, trachea, bronchi).
3. Circulatory (cardiovascular).
4. Nervous (Central nervous system, outgoing nerve fibers, autonomic nervous system, sensory organs).
5. Excretory (kidneys, bladder).
6. Endocrine (endocrine glands - thyroid gland, parathyroid glands, pancreas (insulin), adrenal glands, sex glands, pituitary gland, epiphysis).
7. Musculoskeletal (musculoskeletal - skeleton, muscles attached to it, ligaments).
8. Lymphatic (lymph nodes, lymphatic vessels, thymus - thymus, spleen).
9. Sexual (internal and external genital organs - ovaries (ovum), uterus, vagina, mammary mammary glands, testicles, prostate gland, penis).
10. Immune (red bone marrow at the ends of tubular bones + lymph nodes + spleen + thymus (thymus) - the main organs of the immune system).
11. Integumentary (integuments of the body).

2. General ideas about the processes of growth and development. The main differences between a child's body and an adult

Concept definition

Development- this is the process of complicating the structure and functions of the system over time, increasing its stability and adaptability (adaptive capabilities). Also, development is understood as maturation, the achievement of the full value of a phenomenon. © 2017 Sazonov V.F. 22\02\2017

Development includes the following processes:

1. Growth.
2. Differentiation.
3. Formation.

The main differences between a child and an adult:

1) immaturity of the body, its cells, organs and organ systems;
2) reduced growth (reduced body size and body weight);
3) intensive metabolic processes with a predominance of anabolism;
4) intensive growth processes;
5) reduced resistance to harmful environmental factors;
6) improved adaptation (adaptation) to a new environment;
7) underdeveloped reproductive system - children cannot reproduce.

Periodization of age
1. Infancy (up to 1 year).
2. Pre-school period (1-3 years).
3. Preschool (3-7 years).
4. Junior school (7-11-12 years old).
5. Middle school (11-12-15 years old).
6. Senior school (15-17-18 years old).
7. Maturity. At the age of 18, physiological maturity sets in; biological maturity comes from the age of 13 (the ability to have children); full physical maturity in women occurs at the age of 20, and in men at 21-25 years. Civil (social) maturity in our country comes at the age of 18, and in Western countries - at 21. Mental (spiritual) maturity occurs after 40 years.

Age changes, development indicators

1. Body length

This is the most stable indicator characterizing the state of plastic processes in the body and, to some extent, the level of its maturity.

The body length of a newborn child ranges from 46 to 56 cm. It is generally accepted that if a newborn child has a body length of 45 cm or less, then he is premature.

Body length in children of the first year of life is determined taking into account its monthly increase. In the first quarter of life, the monthly increase in body length is 3 cm, in the second - 2.5, in the third - 1.5, in the fourth - 1 cm. The total increase in body length for the 1st year is 25 cm.

During the 2nd and 3rd years of life, the increase in body length is 12-13 and 7-8 cm, respectively.

The body length in children from 2 to 15 years old is also calculated according to the formulas proposed by I. M. Vorontsov, A. V. Mazurin (1977). The length of the body of children at the age of 8 is taken as 130 cm, for each missing year, 7 cm is subtracted from 130 cm, and 5 cm is added for each excess year.

2. Body weight

Body weight, in contrast to length, is a more variable indicator that reacts relatively quickly and changes under the influence of various causes of exo- (external) and endogenous (internal) nature. Body weight reflects the degree of development of bone and muscle systems, internal organs, subcutaneous fat.

The body weight of a newborn is on average about 3.5 kg. Newborns weighing 2500 g or less are considered premature or born with intrauterine malnutrition. Children born with a body weight of 4000 g or more are considered large.

As a criterion for the maturity of a newborn child, the weight-growth coefficient is used, which is normally 60-80. If its value is below 60, this indicates in favor of congenital malnutrition, and if it is above 80, congenital paratrophy.

After birth, within 4-5 days of life, the child experiences a loss of body weight within 5-8% of the original, that is, 150-300 g (physiological weight loss). Then the body weight begins to increase and around the 8-10th day reaches the initial level. A weight loss of more than 300 g cannot be considered physiological. The main reason for the physiological drop in body weight is, first of all, the insufficient introduction of water and food in the first days after the birth of the baby. The loss of body weight is important in connection with the release of water through the skin and lungs, as well as the original feces, urine.

It should be taken into account that in children of the 1st year of life, an increase in body length by 1 cm, as a rule, is accompanied by an increase in body weight by 280-320 g. When calculating the body weight of children of the 1st year of life with a birth weight of 2500-3000 g for the initial indicator is taken as 3000 g. The rate of increase in body weight of children after a year slows down significantly.

Body weight in children older than a year is determined by the formulas proposed by I. M. Vorontsov, A. V. Mazurin (1977).
The body weight of a child at 5 years old is taken as 19 kg; for each missing year up to 5 years, 2 kg is deducted, and 3 kg is added for each subsequent year. To assess the body weight of children of preschool and school age, two-dimensional centile scales of body weight at different body lengths, based on the assessment of body weight by body length within age and sex groups, are increasingly used as age norms.

3. Head circumference

The head circumference of a child at birth is on average 34-36 cm.

It increases especially intensively in the first year of life, amounting to 46-47 cm by the year. In the first 3 months of life, the monthly increase in head circumference is 2 cm, at the age of 3-6 months - 1 cm, during the second half of life - 0.5 cm .

By the age of 6, the head circumference increases to 50.5-51 cm, by the age of 14-15 - up to 53-56 cm. In boys, its size is slightly larger than in girls.
The size of the head circumference is determined by the formulas of I. M. Vorontsov, A. V. Mazurin (1985). 1. Children of the first year of life: the head circumference of a 6-month-old child is taken as 43 cm, for each missing month from 43, subtract 1.5 cm, for each subsequent month add 0.5 cm.

2. Children from 2 to 15 years old: head circumference at 5 years old is taken as 50 cm; for each missing year, subtract 1 cm, and for each excess year, add 0.6 cm.

Control over changes in the head circumference of children in the first three years of life is an important component of medical activity in assessing the physical development of a child. Changes in the head circumference reflect the general patterns of the biological development of the child, in particular the cerebral type of growth, as well as the development of a number of pathological conditions (micro- and hydrocephalus).

Why is the circumference of a child's head so important? The fact is that a child is born already with a full set of neurons, the same as in an adult. But the weight of his brain is only 1/4 of the brain of an adult. It can be concluded that the increase in brain weight occurs due to the formation of new connections between neurons, as well as due to an increase in the number of glial cells. Head growth reflects these important brain development processes.

4. Chest circumference

Breast circumference at birth averages 32-35 cm.

In the first year of life, it increases monthly by 1.2-1.3 cm, amounting to 47-48 cm by the year.

By the age of 5, the chest circumference increases to 55 cm, by 10 - up to 65 cm.

The circumference of the chest is also determined by the formulas proposed by I. M. Vorontsov, A. V. Mazurin (1985).
1. Children of the 1st year of life: the circumference of the chest of a 6-month-old child is taken as 45 cm, for each missing month, 2 cm should be subtracted from 45, and 0.5 cm should be added for each subsequent month.
2. Children from 2 to 15 years old: chest circumference at 10 years old is taken as 63 cm, for children under 10 years old, the formula 63 - 1.5 (10 - n) is used, for children over 10 years old - 63 + 3 cm (n - 10), where n is the number of years the child is. For a more accurate assessment of the circumference of the chest, centile tables are used, based on the assessment of the circumference of the chest along the length of the body within the age and sex group.

The circumference of the chest is an important indicator that reflects the degree of development of the chest, the muscular system, the subcutaneous fat layer on the chest, which closely correlates with the functional indicators of the respiratory system.

5. Body surface

The surface of the body is one of the most important indicators of physical development. This sign helps to assess not only the morphological, but also the functional state of the organism. It has a close correlation with a number of physiological functions of the body. Indicators of the functional state of blood circulation, external respiration, kidneys are closely related to such an indicator as the surface of the body. Individual medications should also be prescribed according to this factor.

The surface of the body is usually calculated according to the nomogram, taking into account the length and weight of the body. It is known that the surface area of ​​a child's body per 1 kg of its mass is three times greater in a newborn and twice as large in a one-year-old than in an adult.

6. Puberty

Assessing the degree of puberty is important in determining a child's developmental level.

The degree of a child's puberty is one of the most reliable indicators of biological maturity. In everyday practice, it is most often assessed by the severity of secondary sexual characteristics.

In girls, these are pubic (P) and axillary (A) hair growth, breast development (Ma), and age of first menstruation (Me).

In boys, in addition to the growth of hair on the pubis and in the armpits, the voice mutation (V), facial hair (F) and the formation of the Adam's apple (L) are evaluated.

Puberty assessment should be done by a doctor, not a teacher. When assessing the degree of puberty, it is recommended to expose children, especially girls, in parts due to an increased sense of shame. If necessary, the child should be completely undressed.

Generally accepted schemes for assessing the degree of development of secondary sexual characteristics in children by body regions:

Development of pubic hair: no hair - P0; single hair - P1; hair on the central part of the pubis is thicker, longer - P2; hair on the entire triangle of the pubis is long, curly, thick - P3; the hair is distributed over the entire pubic area, passes to the thighs and extends along the white line of the abdomen - P4t.
The development of hair in the armpit: no hair - A0; single hair - A1; hair is sparse in the central part of the cavity - A2; thick hair, curly throughout the cavity - A3.
Development of the mammary glands: glands do not protrude above the surface of the chest - Ma0; the glands protrude somewhat, the areola together with the nipple forms a single cone - Ma1; the glands protrude significantly, together with the nipple and areola, they are cone-shaped - Ma2; the body of the gland takes a rounded shape, the nipples rise above the areola - Ma3.
Development of facial hair: no hair growth - F0; beginning hair growth above the upper lip - F1; coarse hair above the upper lip and on the chin - F2; widespread hair growth above the upper lip and on the chin with a tendency to merge, the beginning of the growth of sideburns - F3; fusion of hair growth zones above the lip and in the chin area, pronounced growth of sideburns - F4.
Voice timbre change: children's voice - V0; mutation (breaking) of the voice - V1; male voice timbre - V2.

The growth of the thyroid cartilage (Adam's apple): no signs of growth - L0; beginning protrusion of cartilage - L1; distinct protrusion (Adam's apple) - L2.

When evaluating the degree of puberty in children, the main attention is paid to the severity of Ma, Me, P indicators as more stable. Other indicators (A, F, L) are more variable and less reliable. The state of sexual development is usually denoted by the general formula: A, P, Ma, Me, which respectively indicate the stages of maturation of each sign and the age of the onset of the first menstruation in girls; e.g. A2, P3, Ma3, Me13. When assessing the degree of puberty in terms of the development of secondary sexual characteristics, a deviation from the average age norms is considered to be ahead or behind with shifts in the indicators of the sexual formula for a year or more.

7. Physical development (assessment methods)

The physical development of a child is one of the most important criteria in assessing his state of health.
From a large number of morphological and functional signs, various criteria are used to assess the physical development of children and adolescents at each age.

In addition to the features of the morphofunctional state of the body, when assessing physical development, it is now customary to use such a concept as biological age.

It is known that individual indicators of the biological development of children in different age periods can be leading or auxiliary.

For children of primary school age, the leading indicators of biological development are the number of permanent teeth, skeletal maturity, and body length.

When assessing the level of biological development of middle-aged and older children, the severity of secondary sexual characteristics, bone ossification, the nature of growth processes are of greater importance, while body length and the development of the dental system are of lesser importance.

To assess the physical development of children, various methods are used: the method of indices, sigma deviations, evaluation tables, regression scales and, more recently, the centile method. Anthropometric indices are the ratio of individual anthropometric features, expressed as formulas. The inaccuracy and fallacy of using indices to assess the physical development of a growing organism has been proved, since as a result of age morphology studies it has been shown that individual dimensions of a child's body increase unevenly (developmental heterochrony), which means that anthropometric indicators change disproportionately. The method of sigma deviations and regression scales, widely used at present to assess the physical development of children, is based on the assumption that the sample under study corresponds to the law of normal distribution. Meanwhile, the study of the form of distribution of a number of anthropometric characteristics (body weight, chest circumference, muscle strength of the arms, etc.) indicates the asymmetry of their distribution, more often right-sided. Because of this, the boundaries of sigma deviations can be artificially overestimated or underestimated, distorting the true nature of the assessment.

centile methodassessment of physical development

These shortcomings are devoid of based on nonparametric statistical analysis. centile method, which has recently been increasingly used in the pediatric literature. Since the centile method is not limited by the nature of the distribution, it is acceptable for assessing any indicators. The method is easy to use, due to the fact that when using centile tables or graphs, any calculations are excluded. Two-dimensional centile scales - "body length - body weight", "body length - chest circumference", in which the values ​​​​of body weight and chest circumference are calculated for the proper body length, make it possible to judge the harmony of development.

Usually, the 3rd, 10th, 25th, 50th, 75th, 90th, 97th centiles are used to characterize the sample. 3rd centile - this is the value of the indicator, less than which it is observed in 3% of the sample members; the value of the indicator is less than the 10th centile - in 10% of the sample members, etc. The gaps between the centiles are named centile corridors. With an individual assessment of indicators of physical development, the level of a trait is determined by its position in one of the 7 centile corridors. Indicators that fell into the 4th-5th corridors (25th-75th centiles) should be considered average, in the 3rd (10th-25th centiles) - below average, in the 6th (75th-90th centiles) ) - above average, in the 2nd (3-10th centile) - low, in the 7th (90-97th centile) - high, in the 1st (up to 3rd centile) - very low, in the 8th (above the 97th centile) - very high.

harmonious is a physical development in which body weight and chest circumference correspond to body length, that is, they fall into the 4th-5th centile corridors (25th-75th centiles).

disharmonious physical development is considered in which body weight and chest circumference lag behind due (3rd corridor, 10-25th centiles) or more than due (6th corridor, 75-90th centiles) due to increased fat deposition.

Sharply disharmonious should be considered physical development, in which body weight and chest circumference lag behind due (2nd corridor, 3-10th centile) or exceed the proper value (7th corridor, 90-97th centile) due to increased fat deposition.

"Square of harmony" (Auxiliary table for assessing physical development)

		Percentage (Centile) Series
		3,00%	10,00%	25,00%	50,00%	75,00%	90,00%	97,00%
Body weight by age	97,00%						Harmonious development ahead of age
	90,00%
	75,00%			Harmonious development according to age
	50,00%
	25,00%
	10,00%	Harmonious development below age norms
	3,00%
Body length by age

Currently, the physical development of the child is assessed in a certain sequence.

Correspondence of the calendar age to the level of biological development is established. The level of biological development corresponds to the calendar age, if most of the indicators of biological development are within the average age limits (M±b). If the indicators of biological development lag behind the calendar age or are ahead of it, this indicates a delay (retardation) or acceleration (acceleration) of the rate of biological development.

After determining the correspondence of the biological age to the passport one, the morphofunctional state of the organism is assessed. Centile tables are used to assess anthropometric indicators depending on age and gender.

The use of centile tables allows us to define physical development as medium, above or below average, high or low, as well as harmonious, disharmonious, sharply disharmonious. The allocation to the group of children with deviations in physical development (disharmonious, sharply disharmonious) is due to the fact that they often have disorders of the cardiovascular, endocrine, nervous and other systems, on this basis they are subject to a special in-depth examination. In children with disharmonious and sharply disharmonious development, functional indicators, as a rule, are below the age norm. For such children, taking into account the cause of deviations in physical development from age indicators, individual plans for recovery and treatment are developed.

3. The main stages of human development - fertilization, embryonic and fetal periods. Critical periods of development of the embryo. Causes of congenital deformities and defects

Ontogenesis is the process of development of an organism from the moment of conception (formation of a zygote) to death.

Ontogeny is divided into prenatal development (prenatal - from conception to birth) and postnatal (postpartum).

Fertilization is the fusion of male and female germ cells, resulting in a zygote (fertilized egg) with a diploid (double) set of chromosomes.

Fertilization occurs in the upper third of the woman's oviduct. The best conditions for this are usually within 12 hours after the release of the egg from the ovary (ovulation). Numerous spermatozoa approach the egg, surround it, come into contact with its membrane. However, only one penetrates the egg, after which a dense fertilization shell forms around the egg, preventing the penetration of other spermatozoa. As a result of the fusion of two nuclei with haploid sets of chromosomes, a diploid zygote is formed. This is a cell that is actually a single-celled organism of a new daughter generation). It is capable of developing into a full-fledged multicellular human organism. But can she be called a full-fledged person? A person and a human fertilized egg have 46 chromosomes, i.e. 23 pairs is a complete diploid set of human chromosomes.

prenatal period lasts from conception to birth and consists of two phases: embryonic (first 2 months) and fetal (3-9 months). In humans, the intrauterine period lasts an average of 280 days, or 10 lunar months (approximately 9 calendar months). In obstetric practice germ (embryo) called a developing organism during the first two months of intrauterine life, and from 3 to 9 months - fruit (foetus) Therefore, this period of development is called fetal, or fetal.

Fertilization

Fertilization most often takes place in the expansion of the female oviduct (in the fallopian tubes). The spermatozoa that have poured into the vagina as part of the sperm, due to their exceptional mobility and activity, move into the uterine cavity, pass through it to the oviducts, and in one of them they meet with a mature egg. Here the sperm enters the egg and fertilizes it. The spermatozoon introduces into the egg the hereditary properties characteristic of the male body, contained in a packaged form in the chromosomes of the male germ cell.

Splitting up

Cleavage is the process of cell division into which the zygote enters. The size of the resulting cells does not increase in this case, because. they do not have time to grow, but only divide.

Once a fertilized egg starts dividing, it is called an embryo. The zygote is activated; its fragmentation begins. Crushing is slow. On the 4th day, the embryo consists of 8-12 blastomeres (blastomeres are cells formed as a result of crushing, they are smaller and smaller after the next division).

Picture: The initial stages of embryogenesis in mammals

I - stage of 2 blastomeres; II - stage of 4 blastomeres; III - morula; IV–V – trophoblast formation; VI - blastocyst and the first phase of gastrulation:
1 - dark blastomeres; 2 - light blastomeres; 3 - trophoblast;
4 - embryoblast; 5 - ectoderm; 6 - endoderm.

morula

Morula ("mulberry") is a group of blastomeres formed as a result of crushing the zygote.

Blastula

Blastula (vesicle) is a single-layer embryo. Cells are located in it in one layer.

The blastula is formed from the morula due to the fact that a cavity appears in it. The cavity is called primary body cavity. It contains liquid. In the future, the cavity is filled with internal organs and turns into the abdominal and chest cavities.

gastrula
The gastrula is a two-layer embryo. The cells in this "germ vesicle" form walls in two layers.

Gastrulation (the formation of a two-layer embryo) is the next stage of embryonic development. The outer layer of the gastrula is called ectoderm. He further forms the skin of the body and the nervous system. It is very important to remember that nervous system comes fromectoderm (outer germ layer, first), therefore, it is closer in its characteristics to the skin than to such internal organs as the stomach and intestines. The inner layer is called endoderm. It gives rise to the digestive system and the respiratory system. It is also important to remember that the respiratory and digestive systems are connected by a common origin.The gill slits in fish are openings in the intestine, and the lungs are outgrowths of the intestine.

Neirula

A neurula is an embryo at the stage of formation of the neural tube.

The vesicle of the gastrula is drawn out, and a groove forms on top. This groove from the depressed ectoderm folds into a tube - this is the neural tube. A cord is formed under it - this is a chord. Over time, bone tissue will form around it and the spine will turn out. Notochord remnants can be found between the vertebrae of the fish. Below the chord, the endoderm extends into the intestinal tube.

The complex of axial organs is the neural tube, notochord, and intestinal tube.

Histo- and organogenesis
After neurulation, the next stage in the development of the embryo begins - histogenesis and organogenesis, i.e. the formation of tissues ("histo-" is a tissue) and organs. At this stage, the third germ layer is formed - mesoderm.
It should be noted that since the formation of organs and the nervous system, the embryo is called fruit.

The fetus, which develops in the uterus, is located in special membranes that form, as it were, a bag filled with amniotic fluid. These waters allow the fetus to move freely in the bag, protect the fetus from external damage and infections, and also contribute to the normal course of childbirth.

Critical periods of development

A normal pregnancy lasts 9 months. During this time, a child weighing about 3 kg or more and 50-52 cm tall develops from a fertilized egg of microscopic size.
The most damaged stages of embryonic development refer to the time when their connection with the mother's body is formed - this is the stage implantation(introduction of the embryo into the wall of the uterus) and stage placenta formation.
1. First critical period in the development of the human embryo refers to the 1st and the beginning of the 2nd week after conception.
2. Second critical period - this is the 3-5th week of development. The formation of individual organs of the human embryo is associated with this period.

During these periods, along with increased embryonic mortality, local (local) deformities and malformations occur.

3. Third critical period - this is the formation of a child's place (placenta), which occurs in a person between the 8th and 11th weeks of embryo development. During this period, the fetus may show general anomalies, including a number of congenital diseases.
During critical periods of development, the sensitivity of the embryo to an insufficient supply of oxygen and nutrients, to cooling, overheating, and ionizing radiation is increased. The ingestion of certain harmful substances into the blood (drugs, alcohol and other toxic substances formed in the body during mother's illnesses, etc.) can cause serious disturbances in the development of the child. Which? Slowdown or arrest of development, the appearance of various deformities, high mortality of embryos.
It is noted that starvation or lack of components such as vitamins and amino acids in the mother's food lead to the death of the embryos or to anomalies in their development.
Infectious diseases of the mother pose a serious danger to the development of the fetus. The effect on the fetus of such viral diseases as measles, smallpox, rubella, influenza, poliomyelitis, mumps, is manifested mainly in the first months pregnancy.
Another group of diseases, for example, dysentery, cholera, anthrax, tuberculosis, syphilis, malaria, affects the fetus mostly in the second and last third of pregnancy.
One of the factors that has a particularly harmful and strong effect on a developing organism is ionizing radiation (radiation).

Indirect, indirect, the effect of radiation on the fetus (through the mother's body) is associated with general violations of the physiological functions of the mother, as well as with changes that have occurred in the tissues and vessels of the placenta. Cells are most sensitive to radiation nervous system and hematopoietic organs of the embryo.
Thus, the embryo is extremely sensitive to changes in environmental conditions, primarily to changes that occur in the mother's body.
Often disturbed embryonic development in cases where the father or mother suffers from alcoholism. Children of chronic alcoholics are often born with mental retardation. The most characteristic thing is that babies behave restlessly, the excitability of their nervous system is increased. Alcohol has a detrimental effect on the germ cells. Thus, it harms future offspring both before fertilization and during the development of the embryo and fetus.

4. Periods of postnatal development. Factors influencing development. Acceleration.
The body of a child after birth is constantly growing and developing. In the process of ontogenesis, specific anatomical and functional features arise, which are called age. Accordingly, the human life cycle can be divided into periods, or stages. There are no clearly defined boundaries between these periods, and they are largely arbitrary. However, the allocation of such periods is necessary, since children of the same calendar (passport), but of different biological age, react differently to sports and work loads; at the same time, their working capacity may be greater or lesser, which is important for solving a number of practical issues of organizing the educational process at school.
The postnatal period of development is the period of life from birth to death.

Periodization of age in the postnatal period:

Infancy (up to 1 year);
- pre-preschool (1-3 years);
- preschool (3-7 years);
- junior school (7-11-12 years old);
- secondary school (11-12-15 years old);
- senior school (15-17-18 years old);
- maturity (18-25)

At the age of 18, physiological maturity sets in.

Biological maturity - the ability to have offspring (from the age of 13). Full physical maturity occurs at the age of 20, and for men - at 21-25 years. Physical maturity is evidenced by the end of growth and ossification of the skeleton.

The criteria for such periodization included a set of features - the size of the body and organs, weight, ossification of the skeleton, teething, the development of endocrine glands, the degree of puberty, muscle strength.
The child's organism develops in the specific conditions of the environment, which continuously acts on the organism and largely determines the course of its development. The course of morphological and functional rearrangements of the child's body in different age periods is influenced by both genetic and environmental factors. Depending on the specific environmental conditions, the development process can be accelerated or slowed down, and its age periods can come earlier or later and have different durations. The qualitative originality of the child's organism, which changes at each stage of individual development, is manifested in everything, and above all in the nature of its interaction with the environment. Under the influence of the external environment, especially its social side, certain hereditary qualities can be realized and developed, if the environment contributes to this, or, conversely, suppressed.

Acceleration

Acceleration (acceleration) is the accelerated growth of a whole generation of people over any historical period of time.

Acceleration is the acceleration of age-related development by shifting morphogenesis to earlier stages of ontogenesis.

There are two types of acceleration - epochal (secular trend, i.e. "the trend of the century", it is inherent in the entire current generation) and intragroup, or individual - this is the accelerated development of individual children and adolescents in certain age groups.

Retardation is a delay in physical development and the formation of functional systems of the body. It is the opposite of acceleration.

The term "acceleration" (from the Latin word acceleratio - acceleration) was proposed by the German doctor Koch in 1935. The essence of acceleration is in an earlier achievement of certain stages of biological development and completion of the maturation of the organism.

There is evidence that due to intrauterine fetal acceleration, full-fledged mature newborns with a weight of over 2500 g and a body length of more than 47 cm can be born at gestational ages of less than 36 weeks.

A doubling of body weight in infants (compared to birth weight) now occurs by 4, and not by 6 months, as was the case in the early twentieth century. If the "cross" of the chest and head circumference values ​​at the beginning of the 20th century was recorded by the 10-12th month, in 1937 - already at the 6th month, in 1949 - at the 5th, then at present the chest circumference becomes equal to the circumference of the head between the 2nd and 3rd months of life. Modern infants have earlier teething. By the year of life in modern children, the body length is 5-6 cm, and the weight is 2.0-2.5 kg higher than they were at the beginning of the century. The circumference of the chest increased by 2.0-2.5 cm, and the head - by 1.0-1.5 cm.
Acceleration of development is also noticeable in children of toddler and preschool age. The development of modern 7-year-old children corresponds to 8.5-9 years in children of the late 19th century.
On average, in preschool children, the body length has increased by 10-12 cm over 100 years. Permanent teeth also erupt earlier.

At preschool age, acceleration can be harmonious. This is the name given to those cases when there is a correspondence between the level of development not only in the mental and somatic spheres, but also in relation to the development of individual mental functions. But harmonic acceleration is extremely rare. More often, along with the acceleration of mental and physical development, pronounced somatovegetative dysfunctions (at an early age) and endocrine disorders (at an older age) are noted. In the mental sphere itself, disharmony is observed, manifested by the acceleration of the development of some mental functions (for example, speech) and the immaturity of others (for example, motor skills and social skills), and sometimes somatic (bodily) acceleration is ahead of mental. In all these cases, disharmonious acceleration is meant. A typical example of disharmonious acceleration is a complex clinical picture, reflecting a combination of signs of acceleration and infantilism ("childhood").

Acceleration in early childhood has a number of features. Acceleration of mental development in comparison with the age norm even by0.5-1 year always makes the child "difficult", vulnerable to stress, especially to psychological situations that are not always caught by adults.

During puberty, which begins in modern girls at 10-12 years old, and in boys at 12-14 years old, the growth rate increases greatly. Earlier comes puberty.

In large cities, puberty of adolescents occurs somewhat earlier than in rural areas. The rate of acceleration of rural children is also lower than in cities.

In the course of acceleration, the average height of an adult for each decade increases by about 0.7-1.2 cm, and weight - by 1.5-2.5 kg.

Concerns have been raised that the acceleration-related shortening of the growth period and the acceleration of puberty may lead to earlier wilting and a shorter lifespan. These fears were not confirmed. The life expectancy of modern people has increased, working capacity is preserved for a longer time. In women, menopause has moved to the 48-50th year of life (at the beginning of the 20th century, menstruation stopped at 43-45 years). Consequently, the childbearing period has lengthened, which can also be attributed to the manifestations of acceleration. In connection with the later onset of menopause and senile changes, metabolic diseases, atherosclerosis and cancer "moved" to an older age. It is believed that the milder course of diseases such as scarlet fever and diphtheria is associated not only with the success of medicine, but also with acceleration due to a change in the reactivity of the body. As a result of acceleration, the reactivity of young children acquired features that were previously characteristic of older children (adolescents).
In connection with the acceleration of physical and puberty, the problems associated with early sexual activity and early marriages have acquired particular importance.

The main manifestations of acceleration according to Yu. E. Veltishchev and G. S. Gracheva (1979):

• increased length and body weight of newborns in comparison with similar values ​​of the 20-30s of our century; at present, the growth of one-year-old children is on average 4-5 cm, and body weight is 1-2 kg more than 50 years ago
• earlier eruption of the first teeth, their change to permanent ones occurs 1-2 years earlier than in children of the last century;
• earlier appearance of ossification nuclei in boys and girls, and in general, ossification of the skeleton in girls ends 3 years, and in boys - 2 years earlier than in the 20-30s of our century;
• an earlier increase in the length and body weight of children of preschool and school age, and the older the child, the more it differs in body size from children of the last century;
• an increase in body length in the current generation by 8-10 cm compared to the previous one;
• the sexual development of boys and girls ends 1.5-2 years earlier than at the beginning of the 20th century; for every 10 years, the onset of menstruation in girls accelerates by 4-6 months.

True acceleration is accompanied by an increase in life expectancy and the reproductive period of the adult population.(I. M. Vorontsov, A. V. Mazurin, 1985).

On the basis of taking into account the ratios of anthropometric indicators and the level of biological maturity, harmonic and disharmonic types of acceleration are distinguished. The harmonic type includes those children whose anthropometric indicators and the level of biological maturity are higher than the average values ​​for this age group, the disharmonic type includes children who have increased body growth in length without simultaneous acceleration of sexual development or early puberty without increased growth in length.

Theories of the causes of acceleration

1. Physical and chemical:
1) heliogenic (the influence of solar radiation), it was put forward by the German school doctor E. Koch, who introduced it in the early 30s. the term "acceleration";
2) radio-wave, magnetic (the influence of a magnetic field);
3) cosmic radiation;
4) an increased concentration of carbon dioxide caused by an increase in production;

5) lengthening of daylight hours due to artificial lighting of the premises.

2. Theories of individual factors of living conditions:
1) alimentary (improvement of nutrition);
2) nutraceutical (improving the structure of nutrition);

3) the influence of hormonal growth stimulants supplied with the meat of animals grown on these stimulants (hormones have been used to accelerate the growth of animals since the 1960s);
4) increased flow of information, increased sensory impact on the psyche.

3. Genetic:
1) cyclic biological changes;
2) heterosis (mixing of populations).

4. Theories of a complex of factors of living conditions:
1) urban (urban) influence;
2) a complex of socio-biological factors.

Thus, a generally accepted point of view has not yet been formed regarding the causes of acceleration. Many hypotheses have been put forward. Most scientists consider nutritional change to be the determining factor in all developmental shifts. This is due to an increase in the amount of consumed high-grade proteins and natural fats per capita.

The acceleration of the physical development of the child requires the rationalization of labor activity and physical activity. In connection with acceleration, the regional standards that we use to assess the physical development of children should be periodically reviewed.

Deceleration

The acceleration process has begun to decline, the average body size of a new generation of people is decreasing again.

Deceleration is the process of canceling acceleration, i.e. slowing down the processes of biological maturation of all organs and systems of the body. Deceleration is currently replacing acceleration.

currently planned deceleration is a consequence of the influence of a complex of natural and social factors on the biology of modern man, as well as acceleration.

Over the past 20 years, the following changes in the physical development of all segments of the population and all age groups have been recorded: the circumference of the chest has decreased, muscle strength has sharply decreased. But there are two extreme trends in body weight changes: insufficient, leading to malnutrition and dystrophy; and excess leading to obesity. All this is regarded as a negative phenomenon.

Reasons for deceleration:

Environmental factor;

Gene mutations;

Deterioration of social living conditions and, above all, the structure of nutrition;

All the same growth of information technologies, which began to lead to overexcitation of the nervous system and, in response to this, to its inhibition;

Decreased physical activity.

A reflex is a response of the body to irritation from the external or internal environment, carried out through the nervous system (CNS) and has an adaptive value.

For example, irritation of the skin of the plantar part of the foot in humans causes reflex flexion of the foot and toes. This is the plantar reflex. Touching the lips of an infant causes sucking movements in him - a sucking reflex. Illumination with bright light of the eye causes constriction of the pupil - the pupillary reflex.
Thanks to reflex activity, the body is able to quickly respond to various changes in the external or internal environment.
Reflex reactions are very diverse. They can be conditional or unconditional.
In all organs of the body there are nerve endings that are sensitive to stimuli. These are receptors. Receptors are different in structure, location and function.
The executive organ, the activity of which changes as a result of a reflex, is called an effector. The path along which impulses pass from the receptor to the executive organ is called the reflex arc. This is the material basis of the reflex.
Speaking about the reflex arc, it must be borne in mind that any reflex act is carried out with the participation of a large number of neurons. A two- or three-neuron reflex arc is just a circuit. In fact, the reflex occurs when not one, but many receptors located in one or another area of ​​the body are stimulated. Nerve impulses during any reflex act, arriving in the central nervous system, are widely distributed in it, reaching its different departments. Therefore, it is more correct to say that the structural basis of reflex reactions is made up of neural circuits of centripetal, central, or intercalary, and centrifugal neurons.
Due to the fact that any reflex act involves groups of neurons that transmit impulses to different parts of the brain, the entire body is involved in the reflex reaction. And indeed, if you are suddenly pricked with a pin in your hand, you will immediately pull it back. This is a reflex reaction. But this will not only reduce the muscles of the hand. Breathing, the activity of the cardiovascular system will change. You will respond with words to an unexpected injection. Almost the entire body was involved in the response. A reflex act is a coordinated reaction of the whole organism.

7. Differences between conditioned (acquired) reflexes and unconditioned ones. Conditions for the formation of conditioned reflexes

Table. Differences between unconditioned and conditioned reflexes

№	reflexes
	Unconditional	Conditional
1	Congenital	Acquired
2	Inherited	Are produced
3	Species	Individual
4	Nerve connections are permanent	Nerve connections are temporary
5	Stronger	Weaker
6	Faster	Slower
7	Difficult to slow down	Easily braked

In the implementation of unconditioned reflexes, mainly the subcortical parts of the central nervous system take part (we also call them "lower nerve centers" . Therefore, these reflexes can be carried out in higher animals even after the removal of the cerebral cortex. However, it was possible to show that after the removal of the cerebral cortex, the nature of the course of unconditioned reflex reactions changes. This gave grounds to speak of a cortical representation of the unconditioned reflex.
The number of unconditioned reflexes is relatively small. They by themselves cannot ensure the adaptation of the body to the constantly changing conditions of life. A great variety of conditioned reflexes are developed during the life of the organism, many of them lose their biological significance when the conditions of existence change, fade away, and new conditioned reflexes are developed. This enables animals and humans to best adapt to changing environmental conditions.
Conditioned reflexes are developed on the basis of unconditioned ones. First of all, you need a conditioned stimulus, or signal. A conditioned stimulus can be any stimulus from the external environment or a certain change in the internal state of the organism. If you feed a dog every day at a certain hour, then by this hour, even before feeding, the secretion of gastric juice begins. Time has become the conditioned stimulus here. Conditioned reflexes for a while are developed in a person subject to the regime of work, eating at the same time, and a constant time for going to bed.
In order for a conditioned reflex to develop, the conditioned stimulus must be reinforced with an unconditioned stimulus, i.e. one that evokes an unconditioned reflex. The ringing of knives in a nightingale will cause a person to salivate only if this ringing has been reinforced by food one or more times. The ringing of knives and forks in our case is a conditioned stimulus, and the unconditioned stimulus that causes a salivary unconditioned reflex is food.
In the formation of a conditioned reflex, the conditioned stimulus must precede the action of the unconditioned stimulus.

8. Patterns of the processes of excitation and inhibition in the central nervous system. Their role in the activity of the nervous system. Mediators of excitation and inhibition. Inhibition of conditioned reflexes and its types

According to the ideas of IP Pavlov, the formation of a conditioned reflex is associated with the establishment of a temporary connection between two groups of cortical cells - between those who perceive conditioned and those who perceive unconditional stimulation.
Under the action of a conditioned stimulus, excitation occurs in the corresponding perceiving zone of the cerebral hemispheres. When the conditioned stimulus is reinforced with an unconditioned stimulus, a second, stronger focus of excitation appears in the corresponding zone of the cerebral hemispheres, which, apparently, takes on the character of a dominant focus. Due to the attraction of excitation from the focus of lesser strength to the focus of greater strength, the nerve pathway is cut, the summation of excitation occurs. A temporary neural connection is formed between the two foci of excitation. This connection becomes stronger, the more often both parts of the cortex are simultaneously excited. After several combinations, the connection is so strong that under the action of only one conditioned stimulus, excitation also occurs in the second focus.
Thus, due to the establishment of a temporal connection, a conditioned stimulus initially indifferent to the organism becomes a signal of a certain innate activity. If the dog hears the bell for the first time, he will give a general orienting reaction to it, but will not salivate. Let's back up the sounding bell with food. In this case, two foci of excitation will appear in the cerebral cortex - one in the auditory zone, and the other in the food center. After several reinforcements of the call with food in the cerebral cortex, a temporary connection arises between the two foci of excitation.
Conditioned reflexes can be inhibited. This happens in those cases when in the cortex of the cerebral hemispheres, during the implementation of the conditioned reflex, a new, sufficiently strong focus of excitation arises, which is not associated with this conditioned reflex.
Distinguish:
external inhibition (unconditional);
internal (conditional).

External
internal
Unconditioned brake - a new biologically strong signal that inhibits the implementation of the reflex
Fading inhibition with repeated repetition of SD without reinforcement, the reflex fades
Estimated; a new stimulus precedes the stimulation of the reflex
Differential - when a similar stimulus is repeated without reinforcement, the reflex fades
Limiting inhibition (super-strong stimuli inhibit the implementation of the reflex)
delayed
Fatigue - inhibits the implementation of the reflex
Conditional brake - when a combination of stimuli is not given reinforcement, one stimulus serves as a brake for another

In the central nervous system, unilateral conduction of excitation is noted. This is due to the peculiarities of synapses, the transfer of excitation in them is possible only in one direction - from the nerve ending, where the mediator is released upon excitation, to the postsynaptic membrane. In the opposite direction, the excitatory postsynaptic potential does not propagate.
What is the mechanism of transmission of excitation in synapses? The arrival of a nerve impulse at the presynaptic ending is accompanied by a synchronous release of a mediator into the synaptic cleft from the synaptic vesicles located in its immediate vicinity. A series of impulses comes to the presynaptic ending, their frequency increases with an increase in the strength of the stimulus, leading to an increase in the release of the mediator into the synaptic cleft. The dimensions of the synaptic cleft are very small, and the neurotransmitter, quickly reaching the postsynaptic membrane, interacts with its substance. As a result of this interaction, the structure of the postsynaptic membrane temporarily changes, its permeability for sodium ions increases, which leads to the movement of ions and, as a result, the emergence of an excitatory postsynaptic potential. When this potential reaches a certain value, a propagating excitation occurs - an action potential.
After a few milliseconds, the neurotransmitter is destroyed by special enzymes.
At present, the vast majority of neurophysiologists recognize the existence in the spinal cord and in various parts of the brain of two qualitatively different types of synapses - excitatory and inhibitory.
Under the influence of an impulse coming along the axon of an inhibitory neuron, a mediator is released into the synaptic cleft, which causes specific changes in the postsynaptic membrane. The inhibitory mediator, interacting with the substance of the postsynaptic membrane, increases its permeability to potassium and chloride ions. Inside the cell, the relative number of anions increases. The result is not a decrease in the internal charge of the membrane, but an increase in the internal charge of the postsynaptic membrane. It is hyperpolated. This leads to the appearance of an inhibitory postsynatic potential, resulting in inhibition.

9. Irradiation and induction

Excitation impulses that have arisen when a particular receptor is irritated, entering the central nervous system, spread to its neighboring sections. This spread of excitation in the CNS is called irradiation. The irradiation is the wider, the stronger and longer the applied irritation.
Irradiation is possible due to numerous processes in centripetal nerve cells and intercalary neurons that connect different parts of the nervous system. Irradiation is well expressed in children, especially at an early age. Children of preschool and primary school age, when a beautiful toy appears, open their mouths, jump, laugh with pleasure.
In the process of differentiation of stimuli, inhibition limits the irradiation of excitation. As a result, excitation is concentrated in certain groups of neurons. Now, around the excited neurons, excitability drops, and they come into a state of inhibition. This is the phenomenon of simultaneous negative induction. The concentration of attention can be seen as a weakening of irradiation and an increase in induction. Dissipation of attention can also be considered as a result of inductive inhibition induced by a new focus of excitation as a result of the emerging orienting reaction. In neurons that have been excited, after excitation, inhibition occurs and, conversely, after inhibition, excitation occurs in the same neurons. This is sequential induction. Sequential induction can explain the increased motor activity of schoolchildren during breaks after prolonged inhibition in the motor area of ​​the cerebral cortex during the lesson. Rest at recess should be active and mobile.

The eye is located in the deepening of the skull - the eye socket. Behind and from the sides, it is protected from external influences by the bony walls of the orbit, and in front - by the eyelids. The inner surface of the eyelids and the anterior part of the eyeball, with the exception of the cornea, is covered with a mucous membrane - the conjunctiva. At the outer edge of the orbit is the lacrimal gland, which secretes a fluid that protects the eye from drying out. Blinking of the eyelids contributes to the even distribution of tear fluid over the surface of the eye.
The shape of the eye is spherical. The growth of the eyeball continues after birth. It grows most intensively in the first five years of life, less intensively - 9-12 years.
The eyeball consists of three shells - outer, middle and inner.
The outer shell of the eye is the sclera. This is a dense opaque white fabric, about 1 mm thick. In the anterior part, it passes into a transparent cornea.
The lens is a transparent elastic formation that has the shape of a biconvex lens. The lens is covered with a transparent bag; along its entire edge, thin, but very elastic fibers stretch to the ciliary body. They are strongly stretched and hold the lens in a stretched state.
In the center of the iris there is a round hole - the pupil. The size of the pupil changes, causing more or less light to enter the eye.
The tissue of the iris contains a special coloring matter - melanin. Depending on the amount of this pigment, the color of the iris ranges from gray and blue to brown, almost black. The color of the iris determines the color of the eyes. The inner surface of the eye is lined with a thin (0.2-0.3 mm), very complex shell - the retina. It contains light-sensitive cells, named rods and cones because of their shape. The nerve fibers from these cells come together to form the optic nerve, which travels to the brain.
The child in the first months after birth confuses the top and bottom of the object.
The eye is able to adapt to a clear vision of objects located at different distances from it. This ability of the eye is called accommodation.
Accommodation of the eye begins already when the object is at a distance of about 65 m from the eye. A clearly pronounced contraction of the ciliary muscle begins at a distance of 10 or even 5 m from the object. If the object continues to approach the eye, accommodation becomes more and more intense and, finally, a clear vision of the object becomes impossible. The smallest distance from the eye at which an object is still clearly visible is called the nearest point of clear vision. In a normal eye, the far point of clear vision lies at infinity.

age physiology

a section of human and animal physiology that studies the patterns of formation and development of the physiological functions of the body throughout ontogeny - from egg fertilization to the end of life. V. f. establishes the features of the functioning of the body, its systems, organs and tissues at different age stages. The life cycle of all animals and humans consists of certain stages or periods. Thus, the development of mammals goes through the following periods: intrauterine (including the phases of embryonic and placental development), newborns, milk, puberty, maturity and aging.

The following age periodization has been proposed for humans (Moscow, 1967): 1. Newborn (from 1 to 10 days). 2. Breast age (from 10 days to 1 year). 3. Childhood: a) early (1-3 years), b) first (4-7 years), c) second (8-12 years old boys, 8-11 years old girls). 4. Adolescence (13-16 years old boys, 12-15 years old girls). 5. Youthful age (17-21 years old boys, 16-20 years old girls). 6. Mature age: 1st period (22-35 years old men, 21-35 years old women); 2nd period (36-60 years old men, 36-55 years old women). 7. Old age (61-74 years old men, 56-74 years old women). 8. Senile age (75-90 years). 9. Long-livers (90 years and above).

I. M. Sechenov (1878) pointed out the importance of studying physiological processes in ontogenetic terms. The first data on the features of the functioning of the nervous system in the early stages of ontogenesis were obtained in the laboratories of I. R. Tarkhanov a (1879) and V. M. Bekhterev a (1886). Researches on V. f. carried out in other countries. The German physiologist W. Preyer (1885) studied blood circulation, respiration, and other functions of developing mammals, birds, and amphibians; Czech biologist E. Babak studied the ontogeny of amphibians (1909). The publication of N. P. Gundobin's book "Features of Childhood" (1906) laid the foundation for a systematic study of the morphology and physiology of the developing human body. Works on V. f. received a large scale from the 2nd quarter of the 20th century, mainly in the USSR. The structural and functional features of the age-related development of individual organs and their systems were revealed: higher nervous activity (L. A. Orbeli, N. I. Krasnogorsky, A. G. Ivanov-Smolensky, A. A. Volokhov, N. I. Kasatkin, M M. Koltsova, A. N. Kabanov), the cerebral cortex, subcortical formations and their relationships (P. K. Anokhin, I. A. Arshavsky, E. Sh. Airapetyants, A. A. Markosyan, A. A. Volokhov and others), the musculoskeletal system (V. G. Shtefko, V. S. Farfel, L. K. Semyonova), the cardiovascular system and respiration (F. I. Valker, V. I. Puzik, N V. Lauer, I. A. Arshavsky, V. V. Frolkis), blood systems (A. F. Tur, A. A. Markosyan). Problems of age-related neurophysiology and endocrinology, age-related changes in metabolism and energy, cellular and subcellular processes, as well as acceleration are being successfully developed (See Acceleration) - accelerate the development of the human body.

The concepts of ontogenesis and aging were formed: A. A. Bogomolets - on the role of the physiological system of connective tissue; A. V. Nagorny - on the significance of the intensity of protein self-renewal (decaying curve); P. K. Anokhin - about systemogenesis, i.e. maturation in ontogenesis of certain functional systems that provide one or another adaptive reaction; I. A. Arshavsky - about the importance of motor activity for the development of the body (energy rule of skeletal muscles); A. A. Markosyan - about the reliability of a biological system that ensures the development and existence of an organism under changing environmental conditions.

In researches on V. f. they use the methods used in physiology, as well as the comparative method, i.e., comparing the functioning of certain systems at different ages, including the elderly and senile. V. f. closely related to related sciences - morphology, biochemistry, biophysics, anthropology. It is the scientific and theoretical basis of such branches of medicine as pediatrics, hygiene of children and adolescents, gerontology, geriatrics, as well as pedagogy, psychology, physical education, etc. Therefore, V. F. is actively developing in the system of institutions related to the protection of children's health, which have been organized in the USSR since 1918, and in the system of physiological institutes and laboratories of the Academy of Sciences of the USSR, the Academy of Sciences of the USSR, the Academy of Medical Sciences of the USSR, and others. introduced as a compulsory subject at all faculties of pedagogical institutes. In coordination of researches on V. f. an important role is played by conferences on age-related morphology, physiology and biochemistry, convened by the institute of age-related physiology of the Academy of Pedagogical Sciences of the USSR. The 9th conference (Moscow, April 1969) united the work of 247 scientific and educational institutions of the Soviet Union.

Lit.: Kasatkin N. I., Early conditioned reflexes in human ontogenesis, M., 1948; Krasnogorsky N. I., Proceedings on the study of higher nervous activity of humans and animals, vol. 1, M., 1954; Parkhon K. I., Age biology, Bucharest, 1959; Paper A., ​​Features of the activity of the child's brain, trans. from German, L., 1962; Nagorny A. V., Bulankin I. N., Nikitin V. N., The problem of aging and longevity, M., 1963; Essays on the physiology of the fetus and newborn, ed. V. I. Bodyazhina. Moscow, 1966. Arshavsky I. A., Essays on age physiology, M., 1967; Koltsova M. M., Generalization as a function of the brain, L., 1967; Chebotarev D. F., Frolkis V. V., Cardiovascular system during aging, L., 1967; Volokhov A. A., Essays on the physiology of the nervous system in early ontogenesis, L., 1968; Ontogeny of the blood coagulation system, ed. A. A. Markosyan, L., 1968; Farber D. A., Functional maturation of the brain in early ontogenesis, M., 1969; Fundamentals of morphology and physiology of the organism of children and adolescents, ed. A. A. Markosyan. Moscow, 1969.

A. A. Markosyan.

Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .

See what "Age Physiology" is in other dictionaries:

age physiology- a science that studies the characteristics of the life of an organism at different stages of ontogenesis. Tasks of VF: 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 ... ... Pedagogical terminological dictionary

AGE PHYSIOLOGY- a section of physiology that studies the patterns of formation and age-related changes in the functions of the whole organism, its organs and systems in the process of ontogenesis (from fertilization of the egg to the termination of individual existence). Life cycle… …

- (from the Greek phýsis - nature and ... Logia) of animals and humans, the science of the vital activity of organisms, their individual systems, organs and tissues and the regulation of physiological functions. F. also studies the patterns of interaction of living organisms with ...

ANIMAL PHYSIOLOGY- (from the Greek phýsis - nature and lógos - teaching), a science that studies the processes of vital activity of organs, organ systems and the whole organism in its relationship with the environment. f. divided into general, private (special), ... ... Veterinary Encyclopedic Dictionary

Physiology- (physiologia, from the Greek physis nature + logos teaching, science, word) - a biological science that studies the functions of the whole organism, its components, origin, mechanisms and laws of life, relations with the environment; allocate F. ... ... Glossary of terms for the physiology of farm animals

Section F., which studies age-related features of life, patterns of formation and extinction of body functions ... Big Medical Dictionary

PHYSIOLOGY- a section of physiology that studies the laws of the functioning of the body in different age periods (in ontogenesis) ... Psychomotor: Dictionary Reference

Animals, a section of animal physiology (See Physiology) that studies the characteristics of physiological functions in various representatives of the animal world by the method of comparison. Together with age physiology (See Age physiology) and ecological ... ... Great Soviet Encyclopedia

I Medicine Medicine is a system of scientific knowledge and practice aimed at strengthening and maintaining health, prolonging people's lives, and preventing and treating human diseases. To accomplish these tasks, M. studies the structure and ... ... Medical Encyclopedia

AHATOMO-PHYSIOLOGICAL CHARACTERISTICS OF CHILDREN- age features of the structure, functions of children. organism, their transformation in the process of individual development. Knowledge and accounting of A. f. about. are necessary for the correct organization of the education and upbringing of children of different ages. The age of the children is conditional ... ... Russian Pedagogical Encyclopedia