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
PREFACE
Clarification of the patterns of child development, the specifics of the functioning of physiological systems at different stages of ontogenesis and the mechanisms that determine this specificity is a necessary condition for ensuring the normal physical and mental development of the younger generation.
The main questions that should arise for parents, teachers and psychologists in the process of raising and educating a child at home, in kindergarten or at school, at a consultation or individual lessons are what kind of child is he, what are his characteristics, 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 extremely important for developing the psychophysiological foundations for organizing educational work, developing adaptation mechanisms in a child, determining the impact of innovative technologies on him, etc.
Perhaps for the first time, the importance of comprehensive knowledge of physiology and psychology for teachers and educators was highlighted by the famous Russian teacher K.D. Ushinsky in his work “Man as a Subject 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 to others - an easy matter - 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 skill; but very few have come to the conviction that, in addition to patience, innate ability and skill, special knowledge is also necessary, although our numerous wanderings could convince everyone of this.” It was K.D. Ushinsky showed that physiology is one of those sciences in which “the facts and those correlations of facts are presented, compared and grouped in which the properties of the subject of education, i.e., man, are revealed.” Analyzing the physiological knowledge that was known, and this was the time of the formation of age-related physiology, K.D. Ushinsky emphasized: “Education has hardly yet drawn from this source, which is just opening.” Unfortunately, even now we cannot talk about the widespread use of age-related physiology data in pedagogical science. The uniformity of programs, methods, and textbooks is a thing of the past, but the teacher still takes little 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 the extent to which 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 during 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 worker. “Upbringing and teaching deals with the whole 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 training.” - M., 1986. - P. 167).
Age physiology- the science of the peculiarities of the body’s vital functions, 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 a child at different age periods.
A textbook on developmental 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 - learning - 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 body and the mechanisms of its adaptation to the external environment at different stages of ontogenesis.
Short description:
Sazonov V.F. Age-related anatomy and physiology (a manual for general education) [Electronic resource] // Kinesiologist, 2009-2018: [website]. Update date: 01/17/2018..__.201_).
Attention! This material is in the process of regular updating and improvement. Therefore, we apologize for any minor deviations from the curriculum 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, therefore the study of anatomy should 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 life processes of an organism and its parts in dynamics.
Physiology studies the course of life processes at the level of the entire organism, individual organs and organ systems, as well as at the level of individual cells and molecules. At the present stage of development of physiology, it is again united with the sciences that were 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 general terms to describe the structure and functioning 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 mathematics? She's also in the middle.
Distal- distant from the center of the body. Are you familiar with the word "distance"? One root.
Proximal- close to the center of the body.
Video:Structure of the human body
Cells and tissues
Characteristic of every organism is a certain organization of its structures.
During the evolution of multicellular organisms, cell differentiation occurred, i.e. Cells of various sizes, shapes, structures and functions appeared. From equally differentiated cells, tissues are formed, the characteristic properties of which are structural unification, morphological and functional community and cell interaction. Different tissues are specialized in function. Thus, a characteristic property of muscle tissue is contractility; nervous tissue - transmission of excitation, etc.
Cytology studies the structure of cells. Histology - structure of tissues.
Organs
Several tissues, combined into a specific 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.
An organ consists of several types of tissues, but one of them predominates and determines its main, leading function. In a muscle, for example, such tissue is muscle tissue.
Organs are working apparatus of the body, specialized to perform complex activities necessary for the existence of a complete organism. The heart, for example, functions as a pump, pumping blood from the veins to the arteries; kidneys - the function of excreting metabolic end products and water from the body; bone marrow - hematopoietic function, etc. There are many organs in the human body, but each of them is part of a complete organism.
Organ systems
Several organs that jointly perform a specific function form an organ system.
Organ systems are anatomical and functional associations of several organs involved in the performance of any complex type of 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. Blood (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, gonads, pituitary gland, pineal gland).
7. Musculoskeletal (musculoskeletal - skeleton, muscles attached to it, ligaments).
8. Lymphatic (lymph nodes, lymphatic vessels, thymus gland - thymus, spleen).
9. Reproductive (internal and external genital organs - ovaries (ovum), uterus, vagina, mammary glands, testicles, prostate gland, penis).
10. Immune (red bone marrow at the ends of long bones + lymph nodes + spleen + thymus (thymus gland) - the main organs of the immune system).
11. Integumentary (body coverings).
2. General ideas about the processes of growth and development. The main differences between a child’s body and an adult’s
Development is the process of increasing the complexity of the structure and functions of a system over time, increasing its stability and adaptability (adaptive capabilities). Development is also understood as maturation, the achievement of the usefulness of a phenomenon. © 2017 Sazonov V.F. 22\02\2017
Development includes the following processes:
- Height.
- Differentiation.
- Formation.
Fundamental differences between a child and an adult:
1) immaturity of the body, its cells, organs and organ systems;
2) reduced height (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 (adjustment) to the new environment;
7) underdeveloped reproductive system - children cannot reproduce.
Age periodization
1. Infancy (up to 1 year).
2. Pre-school period (1-3 years).
3. Preschool (3-7 years old).
4. Junior school (7-11-12 years old).
5. Secondary school (11-12-15 years old).
6. Senior school (15-17-18 years old).
7. Maturity. At the age of 18, physiological maturity begins; biological maturity begins at age 13 (the ability to have children); Full physical maturity in women occurs at 20 years old, and in men at 21-25 years old. Civil (social) maturity in our country occurs at 18 years old, and in Western countries - at 21 years old. Mental (spiritual) maturity occurs after 40 years.
Age-related 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, increases in body length are 12-13 and 7-8 cm, respectively.
Body length in children from 2 to 15 years old is also calculated using the formulas proposed by I.M. Vorontsov, A.V. Mazurin (1977). The body length of children at 8 years old is taken to be 130 cm, for each missing year 7 cm is subtracted from 130 cm, and for each year exceeding 5 cm is added.
2. Body weight
Body weight, unlike length, is a more variable indicator that reacts relatively quickly and changes under the influence of various exo- (external) and endogenous (internal) causes. Body weight reflects the degree of development of the skeletal and muscular systems, internal organs, and 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.
The weight-height coefficient is used as a criterion for the maturity of a newborn child, which is normally 60-80. If its value is below 60, this indicates 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 drop in body weight). Then body weight begins to increase and reaches its initial level around the 8-10th day. A decrease in body weight of more than 300 g cannot be considered physiological. The main reason for the physiological drop in body weight is, first of all, insufficient introduction of water and food in the first days after the birth of the baby. Loss of body weight is important due to the release of water through the skin and lungs, as well as original feces and urine.
It should be taken into account that in children of the 1st year of life, an increase in body length by 1 cm is usually accompanied by an increase in body weight of 280-320 g. When calculating the body weight of children of the 1st year of life with a birth weight of 2500-3000 g per the initial indicator is taken to be 3000 g. The rate of increase in body weight of children after a year slows down significantly.
Body weight in children older than one year is determined according to the formulas proposed by I, M. Vorontsov, A. V. Mazurin (1977).
The body weight of a child at 5 years old is taken to be 19 kg; For each missing year up to 5 years, 2 kg are deducted, and for each subsequent year 3 kg are added. 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-sex groups, are increasingly being used as age norms.
3. Head circumference
The average head circumference of a child at birth is 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 - to 53-56 cm. In boys, its size is slightly larger than in girls.
The size of the head circumference is determined according to 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 one should 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, 1 cm should be subtracted, and for each year exceeding, 0.6 cm should be added.
Monitoring changes in the head circumference of children in the first three years of life is an important component of medical practice when assessing the physical development of a child. Changes in head circumference reflect the general patterns of 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 such importance attached to the circumference of a child’s head? The fact is that a child is born with a full set of neurons, the same as an adult. But the weight of his brain is only 1/4 of that of an adult. We can conclude 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
The average chest circumference at birth is 32-35 cm.
In the first year of life, it increases monthly by 1.2-1.3 cm, reaching 47-48 cm by the year.
By the age of 5, the chest circumference increases to 55 cm, by 10 - to 65 cm.
The chest circumference is also determined using the formulas proposed by I.M. Vorontsov, A.V. Mazurin (1985).
1. Children of the 1st year of life: the chest circumference of a 6-month-old child is taken as 45 cm, for each missing month from 45 one should subtract 2 cm, for each subsequent month add 0.5 cm.
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 of the child. For a more accurate assessment of the chest circumference, centile tables are used, based on the assessment of chest circumference by body length within the age-sex group.
Chest circumference is an important indicator that reflects the degree of development of the chest, muscular system, and subcutaneous fat layer on the chest, which closely correlates with the functional indicators of the respiratory system.
5. Body surface
Body surface 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 body. It has a close correlation with a number of physiological functions of the body. Indicators of the functional state of blood circulation, external respiration, and kidneys are closely related to such indicators as body surface. Individual medications should also be prescribed according to this factor.
The body surface is usually calculated using a nomogram taking into account body length and weight. It is known that the surface area of a child’s body per 1 kg of his weight is three times greater in a newborn, and twice as large in a one-year-old child, than in an adult.
6. Puberty
Assessing the degree of puberty is important to determine the child's developmental level.
The degree of puberty of a child 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, this is the growth of pubic hair (P) and in the armpits (A), the development of the mammary glands (Ma) and the age of first menstruation (Me).
In boys, in addition to the growth of pubic and armpit hair, voice mutation (V), facial hair growth (F) and the formation of the Adam's apple (L) are assessed.
Puberty assessments should be carried out 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 modesty. 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 region:
Development of pubic hair: absence of hair - P0; single hair - P1; hair on the central area of the pubis is thicker, longer - P2; the hair on the entire pubic triangle is long, curly, thick - P3; the hair is located throughout the pubic area, extends to the hips and extends along the white line of the abdomen -P4t.
Development of hair in the armpit: absence of hair - A0; single hair - A1; sparse hair in the central area of the cavity - A2; hair is thick, curly throughout the cavity - A3.
Development of the mammary glands: the glands do not protrude above the surface of the chest - Ma0; the glands protrude somewhat, the isola, together with the nipple, forms a single cone - Ma1; the glands protrude significantly, together with the nipple and areola they have the shape of a cone - Ma2; the body of the gland takes on a rounded shape, the nipples rise above the isola - Ma3.
Development of facial hair: lack of hair growth - F0; beginning hair growth on the upper lip - F1; coarse hair above the upper lip and on the chin - F2; widespread hair growth on the upper lip and chin with a tendency to merge, the beginning of the growth of sideburns - F3; merging of hair growth zones above the lip and in the chin area, pronounced growth of sideburns - F4.
Changing the timbre of the voice: children's voice - V0; mutation (breaking) of the voice - V1; male voice timbre - V2.
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 assessing the degree of puberty in children, the main attention is paid to the severity of indicators Ma, Me, P 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 indicates the stages of maturation of each characteristic and the age of the first menstruation in girls; for example A2, P3, Ma3, Me13. When assessing the degree of puberty by the development of secondary sexual characteristics, a deviation from average age norms is considered to be an advance or lag in shifts in sexual formula indicators of 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 health status.
From a large number of morphological and functional characteristics, different criteria are used to assess the physical development of children and adolescents at each age.
In addition to the characteristics of the morphofunctional state of the body, when assessing physical development, it is currently customary to use such a concept as biological age.
It is known that individual indicators of the biological development of children at 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 degree of expression of secondary sexual characteristics, bone ossification, and the nature of growth processes are of greater importance; body length and the development of the dental system are of less importance.
To assess the physical development of children, various methods are used: the method of indices, sigma deviations, assessment tables-regression scales and, more recently, the centile method. Anthropometric indices are the ratio of individual anthropometric characteristics expressed in the form of formulas. The inaccuracy and fallacy of using indices to assess the physical development of a growing organism has been proven, since studies of age-related morphology have shown that individual body sizes of a child increase unevenly (heterochronicity of development), which means that anthropometric indicators change disproportionately. The method of sigma deviations and regression scales, currently widely used to assess the physical development of children, are based on the assumption that the sample under study corresponds to the law of normal distribution. Meanwhile, a study of the shape of the distribution of a number of anthropometric characteristics (body weight, chest circumference, muscle strength of the arms, etc.) indicates an asymmetry of their distribution, often right-sided. Because of this, the boundaries of sigma deviations can be artificially high or low, distorting the true nature of the assessment.
Centile methodphysical development assessments
Based on nonparametric statistical analysis, these disadvantages are absent. centile method, which has recently been increasingly used in 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 eliminated. 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, allow one to judge the harmoniousness of development.
Typically, the 3rd, 10th, 25th, 50th, 75th, 90th, and 97th centiles are used to characterize the sample. The 3rd centile is the value of the indicator below which it is observed in 3% of the sample members; the value of the indicator is less than the 10th centile - for 10% of the sample members, etc. The intervals between the centiles are named centile corridors. When individually assessing indicators of physical development, the level of the trait is determined by its position in one of the 7 centile corridors. Indicators that fall into the 4th-5th corridors (25-75th centiles) should be considered average, in the 3rd (10-25th centiles) - below average, in the 6th (75-90th 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 physical development in which body weight and chest circumference correspond to body length, that is, they fall into the 4-5th centile corridors (25-75th centiles).
Disharmonious physical development is considered to be in which body weight and chest circumference are behind what should be (3rd corridor, 10-25th centiles) or more than they should be (6th corridor, 75-90th centiles) due to increased fat deposition.
Severely disharmonious physical development should be considered in which body weight and chest circumference lag behind the required values (2nd corridor, 3-10th centiles) or exceed the required value (7th corridor, 90-97th centiles) 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 appropriate to age | |||||||
| 50,00% | ||||||||
| 25,00% | ||||||||
| 10,00% | Harmonious development below age norms | |||||||
| 3,00% | ||||||||
| Body length by age | ||||||||
Currently, the physical development of a child is assessed in a certain sequence.
The correspondence of calendar age to the level of biological development is established. The level of biological development corresponds to calendar age if most indicators of biological development are within the average age range (M±b). If indicators of biological development lag behind calendar age or are ahead of it, this indicates a delay (retardation) or acceleration (acceleration) of the rate of biological development.
After determining whether the biological age corresponds to the passport age, 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 makes it possible to determine physical development as average, above or below average, high or low, as well as harmonious, disharmonious, and sharply disharmonious. The selection of children with deviations in physical development (disharmonious, severely disharmonious) into the group is due to the fact that they often have disturbances in the functioning 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 are, as a rule, below the age norm. For such children, taking into account the reasons for deviations in physical development from age indicators, individual health and treatment plans are developed.
3. The main stages of human development are fertilization, embryonic and fetal periods. Critical periods of embryo development. Causes of congenital deformities and defects
Ontogenesis is the process of development of an organism from the moment of conception (zygote formation) to death.
Ontogenesis is divided into prenatal development (antenatal - from conception to birth) and postnatal (postnatal).
Fertilization is the fusion of male and female reproductive cells, which results 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 sperm approach the egg, surround it, and come into contact with its membrane. However, only one penetrates the egg, after which a dense fertilization membrane forms around the egg, preventing the penetration of other sperm. 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 are a full-fledged diploid set of chromosomes in the human body.
Prenatal period lasts from the moment of conception to birth and consists of two phases: embryonic (first 2 months) And fetal (3-9 months). In humans, the intrauterine period lasts on average 280 days, or 10 lunar months (approximately 9 calendar months). In obstetric practice germ (embryo) called the 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 occurs in the dilation of the female oviduct (in the fallopian tubes). Spermatozoa, released as part of sperm into the vagina, 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 a mature egg. Here the sperm penetrates the egg and fertilizes it. The sperm introduces into the egg the hereditary properties characteristic of the male body, contained in packaged form in the chromosomes of the male reproductive cell.
Splitting up
Cleavage is the process of cell division that the zygote undergoes. The size of the resulting cells does not increase, because they do not have time to grow, but only divide.
Once a fertilized egg begins to divide, 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 fragmentation, they become smaller and smaller after the next division).
Drawing: Initial stages of embryogenesis of mammals
I – stage of 2 blastomeres; II – stage of 4 blastomeres; III – morula; IV–V – trophoblast formation; VI – blastocyst and 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 fragmentation of the zygote.
Blastula
The blastula (vesicle) is a single-layer embryo. The cells are located 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. Subsequently, the cavity is filled with internal organs and turns into the abdominal and thoracic cavities.
Gastrula
The gastrula is a two-layer embryo. The cells in this “germinal vesicle” form walls in two layers.
Gastrulation (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 the 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 and respiratory systems. It is also important to remember that the respiratory and digestive systems are connected by a common origin.In fish, the gill slits are openings in the intestine, and the lungs are outgrowths of the intestine.
Neyrula
A neurula is an embryo at the stage of neural tube formation.
The gastrula vesicle is elongated, and a groove is formed on top. This groove of 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 form a spine. Remnants of the notochord can be found between the vertebrae of the fish. Below the notochord, 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. formation of tissues (“histo-” is tissue) and organs. At this stage, the formation of the third germ layer occurs - mesoderm.
It should be noted that from the moment the organs and nervous system are formed, the embryo is called fruit.
The fetus developing in the uterus is located in special membranes that form a kind of bag filled with amniotic fluid. These waters enable the fetus to move freely in the sac, protect the fetus from external damage and infections, and also contribute to the normal course of labor.
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 embryo development relate to the time when their connection with the maternal body is formed - this is the stage implantation(embryo implantation into the uterine wall) and stage formation of the placenta.
1. First critical period
in the development of the human embryo refers to the 1st and 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 mortality of embryos, local deformities and malformations occur.
3. Third critical period
- this is the formation of a child’s place (placenta), which occurs in humans between the 8th and 11th weeks of embryonic development. During this period, the fetus may exhibit general abnormalities, including a number of congenital diseases.
During critical periods of development, the sensitivity of the embryo to insufficient supply of oxygen and nutrients, to cooling, overheating, and ionizing radiation is increased. The entry into the blood of certain substances harmful to the child (medicines, alcohol and other toxic substances formed in the body due to illnesses of the mother, etc.) can cause serious disturbances in the development of the child. Which? Slowing or stopping development, the appearance of various deformities, high mortality of embryos.
It has been noted that hunger or a lack of components such as vitamins and amino acids in the mother’s food leads to the death of the embryos or to abnormalities 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, manifests itself predominantly in the first months pregnancy.
Another group of diseases, for example, dysentery, cholera, anthrax, tuberculosis, syphilis, malaria, mostly affects the fetus 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).
The indirect, indirect, effect of radiation on the fetus (through the mother’s body) is associated with general disturbances in 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 exposure 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 maternal body.
Embryonic development is often disrupted in cases where the father or mother suffers from alcoholism. Children of chronic alcoholics are often born with weakened mental abilities. The most typical thing is that babies behave restlessly and the excitability of their nervous system is increased. Alcohol has a detrimental effect on reproductive cells. Thus, it causes harm to future offspring both before fertilization and during the development of the embryo and fetus.
4. Periods of postnatal development. Factors influencing development. Acceleration.
After birth, a child’s body continuously grows and develops. In the process of ontogenesis, specific anatomical and functional features arise, called age. Accordingly, a person’s 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 identification of such periods is necessary, since children of the same calendar (passport) age, but different biological ages, react differently to sports and work loads; at the same time, their performance may be greater or less, 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-school (1-3 years);
- preschool (3-7 years);
- junior school (7-11-12 years old);
- secondary school (11-12-15 years);
- senior school (15-17-18 years old);
- maturity (18-25)
At the age of 18, physiological maturity begins.
Biological maturity - the ability to have offspring (from 13 years of age). Full physical maturity occurs at 20 years of age, and for men at 21-25 years of age. Physical maturity is indicated by the completion of growth and ossification of the skeleton.
The criteria for such periodization included a complex of characteristics - body and organ size, weight, skeletal ossification, teething, development of endocrine glands, degree of puberty, muscle strength.
The child’s body develops in specific environmental conditions, which continuously influence the body and largely determine the course of its development. The course of morphological and functional changes in a child’s body at different age periods is influenced by both genetic and environmental factors. Depending on specific environmental conditions, the development process can be accelerated or slowed down, and its age periods can occur earlier or later and have different durations. The qualitative uniqueness of the child’s body, 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 an entire 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. "tendency 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 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 reaching certain stages of biological development and completing the maturation of the organism.
There is evidence that due to intrauterine acceleration of the fetus, full-fledged mature newborns with a weight of over 2500 g and a body length of more than 47 cm can be born at a gestation period of less than 36 weeks.
The doubling of body weight in infants (compared to birth weight) now occurs by 4, and not by 6 months, as was the case at the beginning of the 20th century. If the “cross” of the chest and head circumference values at the beginning of the twentieth century was recorded at the 10-12th month, in 1937 - already at the 6th month, in 1949 - at the 5th month, then at present the chest circumference becomes equal to the head circumference between the 2nd and 3rd months of life. Modern infants start teething earlier. By the age of one year, modern children have a body length of 5-6 cm and a weight of 2.0-2.5 kg higher than they were at the beginning of the century. The chest circumference increased by 2.0-2.5 cm, and the head circumference 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, preschool children's body length has increased by 10-12 cm over 100 years. Permanent teeth also erupt earlier.
In preschool age, acceleration can be harmonious. This is the name for those cases when there is a correspondence of the level of development not only in the mental and somatic spheres, but also in relation to the development of individual mental functions. But harmonious 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, there is disharmony, 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 the mental one. 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 (“childishness”).
Acceleration in early childhood has a number of features. Acceleration of mental development compared to the age norm, even at0.5-1 year always makes a child “difficult”, vulnerable to stressful, especially psychological situations that are not always perceived 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. Puberty occurs earlier.
In big cities, adolescents reach puberty somewhat earlier than in rural areas. The rate of acceleration of rural children is also lower than in cities.
During acceleration, the average height of an adult per decade increases by approximately 0.7-1.2 cm, and weight by 1.5-2.5 kg.
Concerns have been raised that the reduction in growth period and accelerated puberty associated with acceleration may lead to earlier decline and a reduction in life expectancy. These fears were not confirmed. The life expectancy of modern people has increased, and their ability to work remains longer. In women, menopause moved back to the 48-50th year of life (at the beginning of the twentieth century, menstruation stopped at 43-45 years). Consequently, the childbearing period has lengthened, which can also be attributed to manifestations of acceleration. Due to the later onset of menopause and senile changes, metabolic diseases, atherosclerosis and cancer have “moved” to older ages. It is believed that the milder course of diseases such as scarlet fever and diphtheria is associated not only with advances in medicine, but also with acceleration due to changes in the body’s reactivity. 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 sexual maturation, problems associated with early sexual activity and early marriage have become of particular importance.
Main manifestations of acceleration according to Yu. E. Veltishchev and G. S. Gracheva (1979):
- increased length and body weight of newborns compared to similar values in the 20-30s of our century; Currently, the height 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 replacement with 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 at 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 he 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;
- 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 reproductive period of the adult population(I.M. Vorontsov, A.V. Mazurin, 1985).
Based on taking into account the relationships between anthropometric indicators and the level of biological maturity, harmonic and disharmonic types of acceleration are distinguished. The harmonious type includes those children whose anthropometric indicators and level of biological maturity are above 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. length.
Theories of the causes of acceleration
1. Physico-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 (influence of the magnetic field);
3) cosmic radiation;
4) increased concentration of carbon dioxide caused by increased production;
5) lengthening daylight hours due to artificial lighting of premises.
2. Theories of individual factors of living conditions:
1) nutritional (improved nutrition);
2) nutraceutical (improving nutritional structure);
3) the influence of hormonal growth stimulants supplied along with the meat of animals raised on these stimulants (hormones to accelerate the growth of animals began to be used in the 1960s);
4) increased flow of information, increased sensory impact on the psyche.
3. Genetic:
1) cyclical biological changes;
2) heterosis (mixing of populations).
4. Theories of a complex of living conditions factors:
1) urban (city) influence;
2) a complex of socio-biological factors.
Thus, a generally accepted point of view has not yet been formed regarding the reasons for acceleration. Many hypotheses have been put forward. Most scientists consider changes in nutrition to be the determining factor in all developmental shifts. This is due to an increase in the amount of complete proteins and natural fats consumed per capita.
Accelerating the physical development of a child requires rationalization of work activity and physical activity. In connection with acceleration, the regional standards that we use to assess the physical development of children must be periodically reviewed.
Deceleration
The acceleration process has begun to decline, the average body size of the 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 now replacing acceleration.
Currently emerging 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 begun to be recorded: chest circumference has decreased, muscle strength has sharply decreased. But there are two extreme trends in changes in body weight: insufficient, leading to malnutrition and dystrophy; and excessive, leading to obesity. All this is regarded as negative phenomena.
Reasons for deceleration:
Environmental factor;
Gene mutations;
Deterioration of social living conditions and, above all, food structure;
The same growth of information technology, which began to lead to overexcitation of the nervous system and, in response to this, to its inhibition;
Decreased physical activity.
A reflex is the body’s response to irritation from the external or internal environment, carried out through the nervous system (CNS) and having adaptive significance.
For example, irritation of the skin of the plantar part of a person’s foot causes reflex flexion of the foot and toes. This is the plantar reflex. Touching the lips of an infant causes sucking movements in him - the sucking reflex. Illumination of the eye with bright light 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.
All organs of the body contain nerve endings that are sensitive to stimuli. These are receptors. Receptors vary in structure, location and function.
The executive organ whose activity changes as a result of the reflex is called an effector. The path along which impulses travel from the receptor to the executive organ is called a reflex arc. This is the material basis of the reflex.
Speaking about the reflex arc, we must keep 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 diagram. In fact, the reflex occurs when not one, but many receptors located in one or another area of the body are irritated. Nerve impulses during any reflex act, arriving at the central nervous system, spread widely throughout it, reaching its different parts. Therefore, it is more correct to say that the structural basis of reflex reactions is made up of neural chains of centripetal, central, or intercalary, and centrifugal neurons.
Due to the fact that in any reflex act groups of neurons take part, transmitting impulses to various parts of the brain, the whole organism is involved in the reflex reaction. And indeed, if you were unexpectedly pricked in the arm with a pin, you would immediately pull it away. This is a reflex reaction. But this will not only reduce the arm muscles. Breathing and the activity of the cardiovascular system will change. You will react with words to an unexpected injection. Almost the entire body was involved in the response. A reflex act is a coordinated reaction of the entire 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 | Purchased |
| 2 | Inherited | Are being produced |
| 3 | Species | Individual |
| 4 | Neural connections are permanent | Neural connections are temporary |
| 5 | Stronger | Weaker |
| 6 | Faster | Slower |
| 7 | Difficult to brake | Easy to brake |
The implementation of unconditioned reflexes involves mainly the subcortical parts of the central nervous system (we also call them "lower nerve centers"
. Therefore, these reflexes can be carried out in higher animals even after the removal of their cerebral cortex. However, it was possible to show that after removal of the cerebral cortex, the nature of the course of unconditioned reflex reactions changes. This gave grounds to talk about the cortical representation of the unconditioned reflex.
The number of unconditioned reflexes is relatively small. They themselves cannot ensure the body’s adaptation to constantly changing living conditions. A great variety of conditioned reflexes are developed during the life of an organism, many of them lose their biological significance when living conditions 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 body. If you feed a dog every day at a certain hour, then by this hour the secretion of gastric juice begins even before feeding. Here time became the conditioned stimulus. Conditioned reflexes are temporarily developed in a person by observing a work schedule, eating at the same time, and a constant bedtime.
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 the nightingale will cause salivation in a person only if this ringing is reinforced with food one or more times. The clinking of knives and forks in our case is a conditioned stimulus, and the unconditioned stimulus that causes the salivary unconditioned reflex is food.
When a conditioned reflex is formed, the conditioned stimulus must precede the action of the unconditioned stimulus.
8. Patterns of 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 I.P. 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.
When a conditioned stimulus acts, excitement occurs in the corresponding receptive zone of the cerebral hemispheres. When a conditioned stimulus is reinforced by an unconditioned one, 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 a focus of lesser strength to a focus of greater strength, a neural path is blazed, a summation of excitation occurs. A temporary nerve connection is formed between both foci of excitation. This connection becomes stronger the more often both areas of the cortex are simultaneously excited. After several combinations, the connection turns out to be so strong that under the influence of only one conditioned stimulus, excitation also occurs in the second focus.
Thus, due to the establishment of a temporary connection, a conditioned stimulus initially indifferent to the body becomes a signal of a certain innate activity. If the dog hears the bell for the first time, it will give a general approximate reaction to it, but will not salivate. Now let's back up the sound of the 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 bell with food, a temporary connection appears in the cerebral cortex between the two foci of excitation
Conditioned reflexes can be inhibited. This happens in cases where in the cerebral cortex, during the implementation of a conditioned reflex, a new, sufficiently strong focus of excitation arises, not associated with this conditioned reflex.
There are:
external inhibition (unconditional);
internal (conditional).
External
Internal
Unconditional brake - a new biologically strong signal that inhibits the implementation of the reflex
Extinction inhibition with repeated repetition of the SD without reinforcement, the reflex fades away
Approximate; a new stimulus precedes stimulation of the reflex
Differentiation - when a similar stimulus is repeated without reinforcement, the reflex fades away
Extreme inhibition (extremely strong stimuli inhibit the implementation of the reflex)
Delayed
Fatigue - inhibits the implementation of the reflex
Conditioned inhibition - when a combination of stimuli does not provide reinforcement, one stimulus serves as a brake for the other
In the central nervous system, unilateral conduction of excitation is noted. This is due to the characteristics of synapses; transmission of excitation in them is possible only in one direction - from the nerve ending, where the transmitter is released upon excitation, to the postsynaptic membrane. The excitatory postsynaptic potential does not propagate in the opposite direction.
What is the mechanism of excitation transmission in synapses? The arrival of a nerve impulse at the presynaptic terminal is accompanied by the synchronous release of a transmitter into the synaptic cleft from synaptic vesicles located in close proximity to it. A series of impulses arrive at the presynaptic ending; their frequency increases with increasing strength of the stimulus, leading to an increase in the release of the transmitter into the synaptic cleft. The dimensions of the synaptic cleft are very small, and the transmitter, 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 to sodium ions increases, which leads to the movement of ions and, as a consequence, the appearance of an excitatory postsynaptic potential. When this potential reaches a certain value, a spreading excitation occurs - an action potential.
After a few milliseconds, the mediator is destroyed by special enzymes.
Currently, the overwhelming 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 arriving 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 chlorine 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. Its hyperpolation occurs. This leads to the emergence of an inhibitory postsynatic potential, resulting in inhibition.
9. Irradiation and induction
Excitation impulses that arise from irritation of one or another receptor, entering the central nervous system, spread to its neighboring areas. This spread of excitation in the central nervous system is called irradiation. The wider the irradiation, the stronger and longer the irritation caused.
Irradiation is possible due to numerous processes in centripetal nerve cells and interneurons connecting various 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, and 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 decreases, and they enter a state of inhibition. This is the phenomenon of simultaneous negative induction. Concentration of attention can be considered as a weakening of irradiation and strengthening of induction. Dispersion of attention can also be considered as a result of inductive inhibition induced by a new focus of excitation as a result of an emerging orienting reaction. In neurons that were excited, inhibition occurs after excitation 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 during recess should be active and mobile.
The eye is located in the recess of the skull - the orbit. It is protected from external influences from the back and sides by the bony walls of the orbit, and from the front by the eyelids. The inner surface of the eyelids and the front part of the eyeball, with the exception of the cornea, are covered with a mucous membrane - the conjunctiva. At the outer edge of the eye socket there is a lacrimal gland, which secretes a fluid that protects the eye from drying out. The uniform distribution of tear fluid over the surface of the eye is facilitated by blinking of the eyelids.
The eye shape is spherical. 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 membranes - outer, middle and inner.
The outer layer of the eye is the sclera. This is a dense, opaque white fabric, about 1 mm thick. In the anterior part it turns into a transparent cornea.
The lens is a transparent elastic formation shaped like a biconvex lens. The lens is covered with a transparent bag; along its entire edge, thin but very elastic fibers stretch towards the ciliary body. They are strongly stretched and keep the lens stretched.
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 substance - 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) membrane of very complex structure - the retina. It contains light-sensitive cells called cones and rods because of their shape. Nerve fibers coming from these cells come together to form the optic nerve, which travels to the brain.
In the first months after birth, a child confuses the top and bottom of an 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 expressed contraction of the ciliary muscle begins at a distance of the object from the eye of 10 and even 5 m. If the object continues to approach the eye, accommodation becomes more and more intensified and, finally, a clear vision of the object becomes impossible. The shortest distance from the eye at which the object is still clearly visible is called the closest point of clear vision. In a normal eye, the farthest point of clear vision lies at infinity.
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ABSTRACT
AGE PHYSIOLOGY
Age physiology is a science that studies the features of the life processes of an organism at different stages of ontogenesis.
It is an independent branch of human and animal physiology, the subject of which includes the study of the patterns of formation and development of the physiological functions of the body throughout its life path from fertilization to the end of life.
Depending on the age period, age-related physiology is studied: age-related neurophysiology, age-related endocrinology, age-related physiology of muscle activity and motor function; age-related physiology of metabolic processes, cardiovascular and respiratory systems, digestive and excretory systems, physiology of embryonic development, physiology of infants, physiology of children and adolescents, physiology of adulthood, gerontology (the science of aging).
The main objectives of studying age-related physiology are the following:
studying the characteristics of the functioning of various organs, systems and the body as a whole;
identification of exogenous and endogenous factors that determine the functioning of the body at different age periods;
determination of objective age criteria (age standards);
establishing patterns of individual development.
Age-related physiology is closely related to many branches of physiological science and widely uses data from many other biological sciences. Thus, to understand the patterns of formation of functions in the process of individual human development, data from such physiological sciences as cell physiology, comparative and evolutionary physiology, physiology of individual organs and systems: heart, liver, kidneys, blood, respiration, nervous system, etc. are needed.
At the same time, the patterns and laws discovered by age-related physiology are based on data from various biological sciences: embryology, genetics, anatomy, cytology, histology, biophysics, biochemistry, etc. Finally, age-related physiology data, in turn, can be used for the development of various scientific disciplines. For example, age-related physiology is important for the development of pediatrics, pediatric traumatology and surgery, anthropology and gerontology, hygiene, developmental psychology and pedagogy.
History and main stages in the development of age-related physiology
The scientific study of the age-related characteristics of the child’s body began relatively recently - in the second half of the 19th century. Soon after the discovery of the law of conservation of energy, physiologists discovered that a child consumes slightly less energy during the day than an adult, although the child’s body size is much smaller. This fact required a rational explanation. In search of this explanation, the German physiologist Max Rubner conducted a study of the rate of energy metabolism in dogs of different sizes and found that larger animals, per 1 kg of body weight, expend significantly less energy than small ones. Having calculated the surface area of the body, Rubner became convinced that the ratio of the amount of energy consumed is proportional to the size of the body surface - and this is not surprising: after all, all the energy consumed by the body must be released into the environment in the form of heat, i.e. the energy flow depends on the heat transfer surface. It was by differences in the ratio of mass and body surface that Rubner explained the difference in the intensity of energy metabolism between large and small animals, and at the same time between adults and children. Rubner's “surface rule” became one of the first fundamental generalizations in developmental and ecological physiology. This rule explained not only differences in the amount of heat production, but also in the frequency of heart contractions and respiratory cycles, pulmonary ventilation and blood flow volume, as well as in other indicators of autonomic functions. In all these cases, the intensity of physiological processes in a child’s body is significantly higher than in an adult’s body. This purely quantitative approach is characteristic of the German physiological school of the 19th century, consecrated by the names of outstanding physiologists E.F. Pfluger, G.L. Helmholtz and others. Through their works, physiology was raised to the level of natural sciences, on a par with physics and chemistry. However, the Russian physiological school, although rooted in the German one, has always been distinguished by an increased interest in qualitative features and patterns. An outstanding representative of the Russian pediatric school, Dr. Nikolai Petrovich Gundobin back at the very beginning of the 20th century. argued that a child is not just small, he is also in many ways different from an adult. His body is structured and works differently, and at each stage of its development, the child’s body is perfectly adapted to the specific conditions that he has to face in real life. and the ideas were shared and developed by the remarkable Russian physiologist, teacher and hygienist Pyotr Frantsevich Lesgaft, laid the foundations for school hygiene and physical education of children and adolescents. He considered it necessary to deeply study the child’s body and its physiological capabilities.
The central problem of developmental physiology was formulated most clearly in the 20s of the 20th century. German physician and physiologist E. Helmreich. He argued that the differences between an adult and a child are on two levels, which must be considered as independently as possible, as two independent aspects: the child as small body and child developing organism. In this sense, Rubner's “surface rule” considers the child in only one aspect - namely, as a small organism. Much more interesting are those characteristics of the child that characterize him as a developing organism. One of these fundamental features is the discovery in the late 30s Ilya Arkadyevich Arshavsky uneven development of sympathetic and parasympathetic influences of the nervous system on all the most important functions of the child’s body. I.A. Arshavsky proved that sympathotonic mechanisms mature much earlier, and this creates an important qualitative uniqueness of the functional state of the child’s body. The sympathetic department of the autonomic nervous system stimulates the activity of the cardiovascular and respiratory systems, as well as metabolic processes in the body. Such stimulation is quite adequate for an early age, when the body needs an increased intensity of metabolic processes necessary to ensure the processes of growth and development. As the child’s body matures, parasympathetic and inhibitory influences intensify. As a result, the heart rate, breathing rate, and relative intensity of energy production decrease. The problem of uneven heterochrony (multiple times) of development of organs and systems has become the central object of research by the outstanding physiologist academician Peter Kuzmich Anokhin and his scientific school. In the 40s he formulated the concept systemogenesis, according to which the sequence of events unfolding in the body is arranged in such a way as to satisfy the needs of the body that change during development. At the same time, P.K. Anokhin for the first time moved from considering anatomically integral systems to the study and analysis of functional connections in the body. Another prominent physiologist Nikolai Alexandrovich Bernshtein showed how algorithms for controlling voluntary movements gradually form and become more complex during ontogenesis, how mechanisms of higher control of movements spread with age from the most evolutionarily ancient subcortical structures of the brain to newer ones, reaching an increasingly higher level of “construction of movements.” In the works of N.A. Bernstein, it was first shown that the direction of ontogenetic progress in the control of physiological functions clearly coincides with the direction of phylogenetic progress. Thus, the concept of E. Haeckel and A. N. Severtsov that individual development (ontogenesis) is an accelerated evolutionary development (phylogeny) was confirmed using physiological material.
Leading expert in the field of evolution theory, academician Ivan Ivanovich Shmalhausen For many years he also worked on issues of ontogenesis. The material on which I.I. Shmalgauzen made his conclusions was rarely directly related to the physiology of development, but the conclusions from his works on the alternation of stages of growth and differentiation, as well as methodological work in the field of studying the dynamics of growth processes, carried out in the 30s , and are still of great importance for understanding the most important patterns of age-related development. In the 60s, a physiologist Hakob Artashesovich Markosyan put forward the concept of biological reliability as one of the factors of ontogenesis. She relied on numerous facts that showed that the reliability of functional systems increases significantly as the body matures. This was confirmed by data on the development of the blood coagulation system, immunity, and the functional organization of brain activity. In recent decades, many new facts have accumulated that confirm the main provisions of the concept of biological reliability of A.A. Markosyan. At the present stage of development of medical and biological science, research in the field of age-related physiology also continues using modern research methods. Thus, physiological science currently has significant multilateral information concerning the functional activity of any physiological system of the child’s body and its activity as a whole.
Basic patterns of growth in the development of children and adolescents.
The main feature of childhood and adolescence-- a constantly ongoing process of growth and development, during which the gradual formation of an adult takes place. During this process, the quantitative indicators of the body increase (the size of individual organs and the whole body), and the functioning of organs and physiological systems is improved, ensuring the possibility of normal life of a mature person, the main points of which are work activity and the birth of healthy offspring. His future largely depends on how a child and adolescent grows and develops and, therefore, this process from the moment the child is born until the completion of the processes of growth and development should be under the constant control of doctors, parents and teachers. And although every child is completely individual, some patterns of growth and development of children are common to everyone. Child development is a non-stop process in which all stages of slow quantitative changes gradually lead to dramatic transformations in the structures and functions of the child’s body. Often such changes take a sharp, spasmodic form. The normal course of growth and development of a child and adolescent indicates a favorable state of his body, the absence of pronounced harmful influences and, therefore, physical development at this age is one of the leading signs of health, on which its other indicators depend. The level of achieved physical development is necessarily assessed by a doctor during a medical examination and is a necessary criterion for the general assessment of the health status of a child and adolescent. The number of indicators that determine a person’s physical development is quite large. For the purposes of medical and pedagogical practice, relatively easy to measure indicators called somatometric are most often used: body length, body weight, chest circumference. An external examination of the body reveals somatoscopic indicators: shape of the chest, back, feet, posture, muscle condition, fat deposition, skin elasticity, signs of puberty. To assess the functional capabilities of the body, physiometric indicators are used - vital capacity (VC), hand grip strength (dynamometry). All these indicators are taken into account when assessing physical development of children and adolescents, which should be carried out comprehensively, using all of the indicated indicators. To correctly assess the physical development of a child, it is necessary to know the basic patterns of development of children and adolescents and the age-related characteristics of this process, which allows us to understand and explain the activity of individual organs and systems, their interrelation, the functioning of the child’s entire organism at different age periods and its unity with the external environment.
The human life cycle is conventionally divided into three stages: maturation, adulthood and aging. It is possible to draw a chronological boundary for the transition of an organism from one stage to another based on studying the characteristics of its growth and development, interaction with the environment (including the social) environment. The maturation stage is characterized, first of all, by the achievement of sexual maturity, the body's ability and the ability to perform reproductive functions, which ensures the preservation of the species. The preservation of the species is the biological meaning of the individual growth and development of any living creature, including humans. However, it would be a mistake to judge a person's maturity only by the degree of sexual development. An equally important feature is the individual’s readiness to carry out social functions, labor and creative activities, and this is the social and public meaning of his development. Puberty occurs at 13-15 years of age. Labor maturity occurs much later, usually at the end of school or college, i.e. at 17-18 years of age. It comes only with the approaching completion of physical development and the acquisition of experience in social activity. Currently, there is a discrepancy in the timing of puberty and labor maturity. If puberty in modern conditions is observed somewhat earlier, then labor maturity in the conditions of modern production, which requires a fairly high level of training, on the contrary, is later. Therefore, the chronological limit of complete maturation of the body and the onset of maturity should be considered 20-21 years. Namely, by this age, not only the process of full maturation and growth is completed, but also the necessary knowledge is accumulated, moral foundations are formed, i.e., opportunities are created for a person to perform both biological and social functions. At the entire stage of maturation (from birth to full maturity), the growth and development of the body proceeds in accordance with objectively existing laws, the main of which are:
uneven growth and development rates,
non-simultaneous growth and development of individual organs and systems (heterochrony),
Determination of growth and development by sex (sexual dimorphism),
genetic determination of growth and development,
conditioning of growth and development by factors habitat children,
historical development trends (acceleration, deceleration).
Uneven rates of growth and development. The processes of growth and development occur continuously and are progressive in nature, but their pace has a nonlinear dependence on age. The younger the organism, the more intense the processes of growth and development. This is most clearly reflected by the indicators of daily energy consumption. The child is 1-3 months old. daily energy consumption per 1 kg of body weight per day is 110-120 kcal, for a one-year-old - 90-100 kcal. In subsequent periods of the child's life, the decrease in relative daily energy expenditure continues. Uneven growth and development is evidenced by changes in body length in children and adolescents. During the first year of life, the body length of a newborn increases by 47%, during the second - by 13%, and in the third - by 9%. At the age of 4-7 years, body length increases annually by 5-7%, and at the age of 8-10 years - only by 3%.
During puberty, there is a growth spurt; at the age of 16-17 years, a decrease in the rate of growth is observed, and at 18-20 years, the increase in body length practically stops. Changes in body weight, chest circumference, as well as the development of individual organs and systems as a whole occur unevenly. The uneven rate of growth and development of the organism at the stage of maturation is a general pattern. However, during this period some individual characteristics also appear. There are individuals whose rate of development is accelerated, and in terms of maturity they are ahead of their chronological (calendar) age. The opposite relationship is also possible. In this regard, the term “child’s age” must be specified: chronological or biological. The difference between chronological and biological age can reach 5 years. Children with a slow rate of biological development may account for 10-20%. Such children are most often identified before entering school or during training. The lag in biological age in children is manifested by a decrease in most indicators of physical development compared to the average age and is combined with more frequent deviations in the musculoskeletal system, nervous and cardiovascular systems. Students with a slower rate of biological development are less active in class. They experience increased distractibility and an unfavorable type of change in performance. During the educational process, more pronounced tension in the visual, motor analyzer and cardiovascular system is revealed. The most pronounced changes in performance and health status are observed in children with a sharp lag in biological age (a difference of 3 years or more). Fast pace individual child development leads to an advance of biological age compared to chronological age. “Advanced” development is less common in student groups than “lagging” development. Accelerated development is observed more often in girls. Schoolchildren with an accelerated rate of individual development have lower performance capacity than children whose biological age corresponds to the calendar age. Among them there are more people suffering from hypertension and chronic tonsillitis, they have higher morbidity rates, and functional abnormalities are more common and more severe. The highest frequency of deviations from biological age is detected among adolescents.
Thus, individual deviations in the rate of growth and development of a child from the average age cause a discrepancy between the biological age and the chronological age, which, both in the case of advance and especially lag, requires attention from doctors and parents. Criteria for biological age: level of skeletal ossification, timing of teeth eruption and change, appearance of secondary sexual characteristics, onset of menstruation, as well as morphological indicators of physical development (body length and its annual increases). With age, the degree of information content of biological age indicators changes. From 6 to 12 years, the main indicators of development are the number of permanent teeth (“dental age”) and body length. Between 11 and 15 years, the most informative indicators are the annual increase in body length, as well as the degree of expression of secondary sexual characteristics and the age of menstruation in girls. At the age of 15 and later, the appearance of secondary sexual characteristics becomes a very important indicator of development, and indicators of body length and dental development lose their information content. The level of ossification of the skeleton is determined using radiographic studies only in the presence of special medical indications - with pronounced developmental disorders. Non-simultaneous growth and development of individual organs and systems (heterochrony). The processes of growth and development proceed unevenly. Each age is characterized by certain morphofunctional features. The child’s body is considered as a single whole, but the growth and development of its individual organs and systems occur non-simultaneously (heterochronously). Selective and accelerated maturation is ensured by those structural formations and functions that determine the survival of the organism. In the first years of a child’s life, the mass of the brain and spinal cord mainly increases, which cannot be considered accidental: there is an intensive formation of the functional systems of the body. Through the nervous system, the body communicates with the external environment: mechanisms of adaptation to constantly changing conditions are formed, optimal conditions are created for receiving information and performing integrative actions. In contrast, lymphatic tissue does not develop in the first years of life; its growth and formation occur at the age of 10-12 years. Only after 12 years do intensive development of the genital organs and the formation of reproductive function occur. The growth rates of individual parts of the body are also different. During the process of growth, the proportions of the body change, and the child from a relatively large head, short legs and long body gradually turns into a small head, long legs and short body. Thus, intensive development and final formation of individual organs and systems do not occur in parallel. There is a certain order of growth and development of certain structural formations and functions. Moreover, during the period of intensive growth and development of the functional system, its increased sensitivity to the action of specific factors is observed. During the period of intensive brain development, there is an increased sensitivity of the body to the lack of squirrel in food; during the period of development of speech motor functions - to speech communication; during the period of motor development - to motor activity. The child’s body’s ability to perform specific types of activities and its resistance to various environmental factors are determined by the level of maturation of the corresponding functional systems. Thus, the associative sections of the cerebral cortex, which ensure its integral function and readiness for learning at school, mature gradually during the individual development of the child by the age of 6-7 years. In this regard, forced education of children at an early age may affect their subsequent development. The system that transports oxygen to tissues also develops gradually and reaches maturity by 16-17 years. Taking this into account, hygienists prescribe limiting physical activity for children. Only in adolescence, upon reaching the morphofunctional maturity of the cardiovascular and respiratory systems, long-term performance of heavy physical activity and the development of endurance are allowed. Thus, functional readiness for certain types of educational, labor and sports activities is not formed simultaneously, therefore, both types of activities and the impact of environmental factors on various analyzers or functional systems should be differentiated. The hygienic norm throughout the entire stage of maturation of the body changes in accordance with changes in age-related sensitivity to the action of the factor. Heterochronicity of growth and development of individual organs and systems is the scientific basis for differentiated regulation of environmental factors and activities of children and adolescents.
Determination of growth and development by sex (sexual dimorphism).
Sexual dimorphism is manifested in the characteristics of the metabolic process, the rate of growth and development of individual functional systems and the organism as a whole. Thus, boys before the onset of puberty have higher anthropometric indicators. During puberty, this ratio changes: girls are superior to their peers in terms of body length, weight, and chest circumference. There is a crossover of the age curves of these indicators. At the age of 15, the intensity of growth in boys increases, and boys are again ahead of girls in their anthropometric indicators. A second intersection of curves is formed. This double cross of the curves of age-related changes in physical development indicators is characteristic of normal physical development. At the same time, there is an unequal rate of development of many functional systems, especially muscular, respiratory and cardiovascular. For example, the strength of the hand or back extensor muscles in boys of all ages is higher than that of their peers. There are differences not only in physical performance, but also in psychophysiological indicators. age physiology organism child
And so, along with those common to both sexes growth patterns of children and adolescents There are differences in the rates, timing and indicators of growth and development of boys and girls. Sexual dimorphism is taken into account when rationing physical activity and organizing the educational process. Sex differences in the growth and development of the body are important in the vocational guidance of schoolchildren, sports selection and training of young athletes. Domestic hygienic science is developing the concept of the correspondence, first of all, of educational loads to the functional capabilities of a growing organism and the advisability of its training for the purpose of protecting and promoting health. In accordance with this, in our country, activity standards are being developed based on the age-sex principle and recommendations are given on the reasonable training of a growing organism in order to help increase its reserve abilities and more fully use the physical capabilities of the body inherent in nature.
Inside uterineuhstages of development.
In intrauterine development of a person, three periods are conventionally distinguished:
1 The implantation period lasts from the moment of fertilization to 2 weeks. This period is characterized by rapid systematic fragmentation of the fertilized egg, its movement along the fallopian tube to the uterine cavity; implantation (attachment of the embryo and penetration into the uterine mucosa) on the 6-7th day after fertilization and further formation of the membranes, creating the necessary conditions for the development of the embryo. They provide nutrition (trophoblast), create a liquid habitat and mechanical protection (amniotic fluid).
2 The embryonic period lasts from the 3rd to the 10-12th weeks of pregnancy. During this period, the rudiments of all the most important organs and systems of the future baby are formed, the torso, head, and limbs are formed. The placenta is developing - the most important organ of pregnancy, separating two bloodstreams (mother and fetus) and ensuring metabolism between mother and fetus, protecting it from infectious and other harmful factors, from the mother’s immune system. At the end of this period, the embryo becomes a fetus with a child-like configuration.
3 The fetal period begins from the 3rd month of pregnancy and ends with the birth of a child. Nutrition and metabolism of the fetus is carried out through the placenta. There is rapid growth of the fetus, formation of tissues, development of organs and systems from their rudiments, formation and formation of new functional systems that ensure the life of the fetus in the womb and the child after birth.
After the 28th week of pregnancy, the fetus begins to form a supply of valuable substances necessary in the first time after birth - calcium salts, iron, copper, vitamin B12, etc. The surfactant matures, ensuring normal lung function. Intrauterine development is influenced by various environmental factors. They have the most significant effect on the organs that develop most intensively at the time of exposure.
Postnatal period
The postnatal period is a stage of ontogenesis, during which the growing organism begins to adapt to the influence of the external environment.
The postnatal period goes through three periods of development:
1. Juvenile (before puberty)
2. Mature (or pubertal, adult sexually mature state)
3. Hydrogen (old age) periods.
In humans, the postnatal period is conventionally divided into 12 periods (age periodization):
1. Newborns - from birth to 10 days
2. Infancy - from 10 days to 1 year
3. Early childhood - from 1 year to 3 years
4. First childhood - from 4 years to 7 years
5. Second childhood - 8 - 12 years (boys), 8 - 11 years (girls)
6. Adolescence - 13 - 16 years (boys), 12 - 15 years (girls)
7. Youth period - 17 - 18 years (boys), 16 - 18 years (girls)
8. Mature age, period I: 19 - 35 years (men), 19 - 35 years (women)
9. Mature age, period II: 36 - 60 years (men), 36 - 55 years (women)
10. Old age - 61 - 74 years (men), 56 - 74 years (women)
11. Old age 75 - 90 years (men and women)
12. Long-livers - 90 years and older.
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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 Ontogenesis A -
from fertilization of the egg to the end of life. V. f. establishes the peculiarities 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. For humans, the following age periodization has been proposed (Moscow, 1967): 1. Newborn (from 1 to 10 days). 2. Infancy (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. Adolescence (boys 17-21 years old, girls 16-20 years old). 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 for men, 56-74 years for women). 8. Old age (75-90 years). 9. Long-livers (90 years and above). The importance of studying physiological processes in ontogenetic terms was pointed out by I.M. Sechenov(1878). The first data on the peculiarities 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). Research on V. f. were also 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 “Peculiarities of Childhood” (1906) marked the beginning of 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. Structural and functional features of the age-related development of individual organs and their systems have been identified: 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), cerebral cortex, subcortical formations and their relationships (P. K. Anokhin, I. A. Arshavsky, E. Sh. Airapetyants, A. A. Markosyan, A. A. Volokhov, etc.), musculoskeletal system (V. G. Shtefko, V. S. Farfel, L. K. Semyonova), 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) -
accelerating 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 - about the value of the intensity of protein self-renewal (damped curve); P.K. Anokhin - about systemogenesis, i.e. the 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 the biological system that ensures the development and existence of the organism under changing environmental conditions. In studies on V. f. They use 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. is closely connected with 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 USSR Academy of Sciences, the Academy of Pedagogical Sciences of the USSR, the Academy of Medical Sciences of the USSR, etc. Since 1970, the course of V. f. introduced as a compulsory subject in all faculties of pedagogical institutes. In coordination of research on V. f. Conferences on age-related morphology, physiology and biochemistry, convened by the Institute of Age-related Physiology of the Academy of Sciences of the USSR, play a major role. The 9th conference (Moscow, April 1969) brought together 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; Parhon K.I., Age biology, Bucharest, 1959; Paper A., Peculiarities of child brain activity, trans. from German, L., 1962; Nagorny A.V., Bulankin I.N., Nikitin V.N., Problem of aging and longevity, M., 1963; Essays on the physiology of the fetus and newborn, ed. V. I. Bodyazhina, M., 1966; Arshavsky I. A., Essays on age-related physiology, M., 1967; Koltsova M. M., Generalization as a function of the brain, L., 1967; Chebotarev D.F., Frolkis V.V., Cardiovascular system in aging, L., 1967; Volokhov A. A., Essays on the physiology of the nervous system in early ontogenesis, Leningrad, 1968; Ontogenesis 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 body of children and adolescents, ed. A. A. Markosyan, M., 1969. A. A. Markosyan.
Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .
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