Topic 2. INFLUENCE OF HEREDITY AND ENVIRONMENT ON THE DEVELOPMENT OF CHILDREN'S ORGANISM

2.1. Heredity and its role in the processes of growth and development

Heredity is the transmission of parental traits to children. Some hereditary qualities (nose shape, hair color, eyes, facial contours, ear for music, singing voice, etc.) do not require the use of any devices for their fixation, others associated with the cytoplasm and nuclear DNA (metabolism, blood type, the usefulness of the set of chromosomes, etc.), require quite complex studies.

The growth and development of the child depend on the received hereditary inclinations, but the role of the environment is also great. It is customary to distinguish between favorable and unfavorable (or burdened) heredity. The inclinations that ensure the harmonious development of the abilities and personality of the child belong to favorable heredity. If the appropriate conditions are not created for the development of these inclinations, then they fade away, not reaching the level of development of the giftedness of the parents. For example, a singing voice, ear for music, drawing abilities, etc. do not develop.

A burdened heredity cannot always ensure the normal development of a child, even in a good upbringing environment. Usually it is the cause of anomalies (deviations from the norm) and even deformities, and in some cases the cause of prolonged illness and death. In addition, the cause of anomalies in children may be the alcoholism of parents and the harmfulness of their profession (for example, work related to radioactive substances, pesticides, vibration).

However, heredity, especially unfavorable, should not be considered something inevitable. In some cases, it can be corrected and managed. For example, methods have been developed for the treatment of hemophilia - the introduction of a specific blood protein.

The birth of children with unfavorable heredity can be avoided by consulting geneticists. In particular, such consultations contribute to the prevention of closely related marriages, which are the cause of the birth of abnormal children.

Timely detection of inherited traits in children makes it possible to send some children to special schools for the gifted, and others to auxiliary schools. Children with mental and physical disabilities (mentally retarded, deaf, blind) in auxiliary schools are involved in socially useful work, acquire literacy and improve their intellectual development. A huge merit in correcting unfavorable heredity in children belongs to oligophreno-, deaf- and typhlopedagogy.

Qualified teachers in special schools improve the mathematical, musical and other inclinations of children, which is associated with a huge amount of work for their development. The teacher should be aware that parents often see extraordinary abilities in their child, although in fact he may have very modest inclinations. Therefore, it is very important to tell parents in time how to develop in the child that tendency that is revealed in him and which he, perhaps, inherited from his grandfathers, and not from his parents. Such a manifestation of abilities is associated with a feature of heredity: its long-term stability, when signs are transmitted over many generations and do not always appear in the first generations (this is the so-called recessive heredity).

Relationship between the body and the environment. The founder of Russian physiology I.M. Sechenov wrote that “an organism without an external environment that supports its existence is impossible, therefore the scientific definition of an organism must also include the environment that influences it.” Consequently, outside of nature and the social environment, in essence, there is no human being.

I.P. Pavlov, developing this position, came to the conclusion that it is necessary to speak of a person as an integral organism, which is closely interconnected with the external environment and exists only as long as a balanced state of him and the environment is maintained. In this regard, all reflexes were considered by Pavlov as reactions of constant adaptation to the outside world (for example, a person's adaptation to different climatic conditions or different habitats).

Thus, the development of a person cannot be adequately assessed without taking into account the environment in which he lives, is brought up, works, without taking into account those with whom he communicates, and the functions of his body - without taking into account the hygienic requirements for the workplace, home environment, without taking into account the relationship of man with plants, animals, etc.

2.2. man and plants

The world of flora is a huge pantry that gives a person the necessary nutrients that are synthesized by plants. From vegetable raw materials, a person makes medicines, clothes, builds dwellings, etc. Due to the specifics of life, plants purify the air of carbon dioxide and make up for the loss of oxygen in the atmosphere.

But the plant world cannot be fully appreciated without studying its representatives such as bacteria, fungi, yeast, which play a special role in the life processes of all organisms. Unlike green plants, they lack chlorophyll, which is necessary for the synthesis of carbohydrates, but they have the ability to cause fermentation processes (this is due to the production of alcohols, souring of milk, etc.). Among them there are both useful and necessary for a person microorganisms, and harmful, which include pathogens.

Microscopic representatives of the plant world are diverse in form and biological properties. For example, some of them are spherical in shape, which is why they are called cocci (from the Greek kokkos - grain). Under a microscope, they can be seen lying either in groups, like bunches of grapes (staphylococci), or in chains, like beads (streptococci), or in pairs (gonococci). The former are less dangerous than the latter, but they are all disease-causing.

A number of representatives of microorganisms have the form of sticks. They are called bacilli, or bacteria (from the Greek. bakterion - stick). Some rod-shaped microbes in the course of evolution turned into corkscrew-like ones - spirilla, or spirochetes (for example, the causative agent of syphilis). Other rod-shaped bacteria, over time, under the influence of certain factors, bent in the form of a comma. In a living culture, they make oscillatory movements. These are vibrios (for example, vibrio El Tor - the causative agent of cholera).

Regarding humans, microorganisms are divided into saprophytes (these are microbes that do not harm the body, feeding on dead epithelial cells or undigested food residues in the intestine) and parasites - microbes that destroy the body. Pathogenic microorganisms can enter the human or animal body. This process is called infection or infection. Parasitic microbes, entering the body, can affect it slowly (like staphylococci) or sharply and suddenly (acutely), therefore the diseases caused by them are called acute (for example, diphtheria, dysentery, etc.).

A person fights microbes, uses disinfection, destroying pathogens in the external environment by physical methods (high temperature, steam under pressure, ultraviolet rays, etc.), mechanical, chemical (solutions of acids, salts, alkalis, etc.) and biological means (antibiotics and etc.). These measures prevent infection of the body, increase its resistance. Thus, in interaction with the microcosm, a person must comply with the norms and rules developed by hygiene (school, communal, food hygiene, etc.).

2.3. Man and animals

Human life is impossible without relationships with higher and lower animals. Most of the higher animals are a source of meat, milk, raw materials for the manufacture of clothing and footwear, etc. But they can also cause significant harm to humans. For example, a sick animal becomes a carrier of infectious agents.

Diseases that humans contract from animals are called zoonotic diseases. To destroy their pathogens, they carry out disinfection and disinsection (destruction of insects, rodents, etc.). Domestic animals infected with such dangerous diseases as glanders, plague, and rabies are subject to destruction.

Microscopic animals are rickettsia, which are visible only in an electron microscope. Rickettsia are the causative agents of a number of diseases called rickettsiosis. Of these, typhus is the most dangerous for humans.

Of the simplest unicellular animals that parasitize in humans, one can name dysenteric amoeba and Plasmodium, the causative agent of malaria. The carriers of the first are flies and a sick person, Plasmodium is spread by malarial mosquitoes.

Some diseases are caused by various types of worms. They are called helminths, and diseases are called helminthiases.

To combat anthroponotic (affecting only humans) diseases, the causative agents of which belong to the world of animals and plants, sera and vaccines are used.

Serum is a blood product of a person or animal, which is devoid of formed elements and some proteins, but contains specific substances against a particular disease.

A specially prepared culture of killed or weakened pathogens (for example, against poliomyelitis, tuberculosis, etc.) is called a vaccine.

2.4. The effect of viruses on the human body

Viruses form a large group of parasites of humans, animals and plants. They can cause a number of serious diseases, such as natural and chicken pox, poliomyelitis, etc. Viruses are studied by a special science - virology.

Viruses are peculiar living beings, intracellular parasites of plants, animals, humans and microorganisms. They do not have a cellular structure and autonomous metabolism. A unit (or individual) of a mature virus is called a vibrio; its genetic material is one molecule of nucleic acid (RNA or DNA) protected by a protein sheath. Viruses reproduce only in the cells of the host organism, i.e., where they parasitize.

In medicine, for the prevention of viral diseases, sterilization (treatment with high temperature, chemical solutions), irradiation with ultraviolet rays of natural and artificial origin, and x-rays are used.

Sources of pathogens. Ways of transmission of the disease. Sick people or animals can spread many diseases. Pathogens spread through exhaled air, sputum, feces and vomit, discharge from purulent wounds, ulcers and hair loss. Those pathogens that are released by the source into the external environment are kept alive or die. Having penetrated the body, they begin to multiply and parasitize, causing harm.

In the chain of movement of pathogens from a diseased organism to a healthy one, the duration of their stay in the external environment, as well as the degree of their resistance to its various factors, play an important role. Being outside the body, pathogens die after a few days or hours, and are susceptible to disinfectants, but some of them (for example, anthrax, etc.) can remain viable for several years.

The following ways of transmission of pathogens from a diseased organism to a healthy one are distinguished.

1. A contact route of transmission is possible as a result of contact with the patient. Contact can be direct (bite, kiss, etc.) and indirect, including contact with objects used by the patient (for example, dishes, food, etc.). Diphtheria, smallpox natural, Botkin's disease, and other diseases are transmitted in this way.

There may be cases when pathogens are transmitted through caregivers who do not comply with sanitary and hygienic requirements. This type of transfer of pathogens is called transfer to a third party.

To avoid infection, you should not enter the room of a contagious patient, kiss him and maintain other types of contact (for example, use his things, etc.).

2. The airborne route is the transmission of microbes through the air and with droplets of saliva when coughing and sneezing. Influenza, diphtheria, measles and other infections are transmitted in this way. Constant ventilation of rooms (classrooms, apartments), systematic cleaning with the use of disinfectants, exposure to ultraviolet rays help prevent infection.

3. The most dangerous is the water-food way of spreading infectious diseases, when pathogens enter the body with contaminated water or food. This route of infection is the most widespread; pathogens of gastrointestinal diseases (dysentery, infectious jaundice, etc.) are transmitted through it.

To prevent gastrointestinal diseases, in addition to the rules of personal hygiene, it is necessary to thoroughly wash vegetables, fruits and berries with hot boiled water before use. Particular attention should be paid to the quality of drinking water and cooked food.

4. The transmission route involves the transmission of pathogens with the help of insects. At the same time, some insects carry pathogens on their bodies and limbs (for example, flies), others excrete pathogens with saliva when bitten (for example, lice). Some animals carry parasites (for example, mice and rats - fleas infected with plague). Ways to combat the spread of infection are deratization, disinfestation and disinfection, as well as treatment of sick animals and people (including bacillus carriers); medical control over meat and dairy products and farms, places of sale of prepared food and foodstuffs.

2.5. Hygiene of clothes and shoes

Hygienic requirements for clothing depend on the conditions of its operation and the characteristics of human activity. For the manufacture of clothing, the use of materials that emit chemicals in quantities exceeding the maximum permissible limits is prohibited. Polymeric materials for clothing must have chemical stability, i.e., do not release various ingredients toxic to the body into the environment. Clothing materials may contain non-polymerized monomers, as well as components of various auxiliary substances used for processing natural and synthetic fabrics (impregnations, dressings, etc.).

Research methods. During the hygienic assessment of clothing, the materials from which it is made are examined and a physiological and hygienic study of experimental and prototypes is carried out.

To determine the content of toxic substances, the latest methods of quantitative analysis are used, including chromatographic, spectrophotometric, etc. If there is no information about the toxic properties and the nature of their effects on the body, a toxicological study is carried out on experimental animals (mice, rats, guinea pigs). Using modern biochemical, physiological, immunological, pathomorphological and other research methods, local irritating, allergenic, resorptive effects are studied. When evaluating materials intended for children's clothing, toxicological experiments are carried out on growing animals, taking into account their age-related reactivity.

Giving an assessment of the material for the manufacture of clothing from a hygienic point of view, they analyze heat and moisture conductivity, hygroscopicity, breathability. In addition, the mechanical properties of materials are determined, i.e. thickness under load, elasticity, extensibility. In connection with the widespread use of polymers, it became necessary to hygienically evaluate textile materials for the level of electrostatic field strength and the time for the charge to drain from it.

Hygienic requirements for certain types of clothing. Separate hygiene requirements are developed for each layer of clothing. Thus, summer clothing should not impede heat transfer and sweat evaporation. Therefore, for its manufacture, materials with good hygroscopicity (at least 7%), air permeability (at least 330-370 degrees per 1 cubic dm), low thermal resistance (0,09-0,11 degrees per 1 kcal) and electrostatic field strength.

It has been established that the lighter the clothing, the more rays it reflects, the less it absorbs them and the less it heats up. Therefore, light-colored clothes are good for summer, and dark ones, which absorb more heat, are good for winter. The best materials for summer clothes are cotton, natural linen and artificial (viscose, silk) fabrics, which have good breathability and moisture conductivity and have little thermal resistance.

Another important indicator of the properties of clothing is its water capacity, i.e., the ability of a fabric to be saturated with water: the more air present in the pores of the clothing fabric is replaced by water, the lower its breathability and the greater its thermal conductivity. As a result, sweat and gases emitted by the skin (carbon dioxide, carbon monoxide, etc.) accumulate under clothing, heat loss increases significantly, which worsens health and reduces performance. In addition, soaking clothing with water increases its weight.

Woolen fabric has the least water capacity and the greatest air permeability when wet. For example, the water content of woolen flannel is 13%, cotton flannel - 18,6%, cotton tights - 27,2%, silk tights - 39,8%, linen tights - 51,7%. Based on this, at low air temperatures and during rain or snow, physical work is best done in clothes made of woolen fabric, and in summer - in clothes made of linen. It is acceptable to use materials from a mixture of natural, viscose artificial fibers with synthetic polyester, while the share of the latter should be no more than 30-40%.

Materials for winter clothing should have high thermal insulation properties, and its top layer should have a little breathability to provide protection from the wind. In the cold season, clothing made of dense, porous fabrics with good heat-shielding properties (woolen, half-woolen, etc.) is rational. It is advisable to wear clothes made from a mixture of viscose with natural (wool) and synthetic fibers, the content of which should be approximately 40-45%.

Outerwear (suits, coats) are sewn from materials of considerable thickness and porosity (drape, cloth). The necessary wind protection is provided by pads made of materials with low air permeability. In addition, synthetic materials are used for the top layer, which reduces the weight of clothing by 30-40%. Clothes are more hygienic the less they weigh.

For the top layer, the best fabrics are those that absorb moisture poorly and give it away quickly, i.e., fabrics that have a faster rate of moisture evaporation and a shorter drying time. Of the synthetic materials, lavsan, nitron and capron have the highest rate of evaporation from the surface. In order to impart water-repellent properties, many of these fabrics are treated with special impregnations and latexes.

The main role in heat transfer belongs to the thermal conductivity of clothing, which depends on porosity, i.e., on the air content in the fabric. Since air is a poor conductor of heat, the greater the porosity of the fabric, the less it conducts heat, therefore, the less heat transfer. The porosity of fur averages 95-97%, wool - up to 92%, flannel - 89-92%, tights - 73-86%, linen fabrics - 37%. It is clear that fur and woolen clothing retains heat better than linen, so it is more suitable for winter, and linen for summer.

Underwear should be light, soft, light and have great breathability and hygroscopicity. The most practical and appropriate knitted underwear made of knitwear or thin cotton (or linen) fabric. This linen washes well. Woolen underwear irritates the skin and is washed worse. Underwear should be changed at least once a week, as dirt, waste products and germs accumulate on it. In summer, as well as during intensive muscular work, underwear is changed more often. Cotton or linen fabric is suitable for bed linen. Bed linen also needs to be changed and washed once a week.

A headdress for summer should be light, comfortable, light, breathable, not put pressure on the head and protect it from direct sunlight. A winter headdress should, on the contrary, be dark, light and contain a lot of air in the pores.

Hygienic requirements for children's clothing. Since children's skin has a relatively large surface area, it is thinner and more delicate and, in addition, contains up to one-third of the body's total blood, heat transfer through the skin in children is greater than in adults. In this regard, the hygienic requirements for children's clothing are much stricter than for adult clothing.

The outerwear of children and adolescents should be light in summer, dark in winter, freely fit the body, do not interfere with breathing, blood circulation, do not restrict movement, that is, correspond to the size of the body. The size of the child's clothing increases as it grows. Clothing that is not tailored to fit can cause injury to children because it tends to hit the surroundings. It is necessary to avoid tightening the body with belts, elastic bands. In winter, you can not wrap up children, wear clothes that do not correspond to the air temperature. On the contrary, given the great mobility of children, their winter clothes should be slightly less warm than necessary to maintain body temperature at rest. Children should not wear heavy coats that restrict movement. Children's clothing should be comfortable and light, because heavy clothing contributes to the appearance of scoliosis in a child and the formation of an incorrect posture; in such clothes, children quickly get tired. In addition, tight clothing can interfere with blood circulation and breathing.

For clothes of young children, it is best to use materials made from natural fibers (cotton, wool). The use of synthetic fibers, as well as materials treated with various impregnations, should be avoided.

Hygienic requirements for shoes. The design of the shoes and the material from which they are made must meet hygienic requirements. First of all, shoes should ensure the physiological functions of the foot, correspond to its anatomical and physiological characteristics, not squeeze it, not disrupt blood and lymph circulation, innervation, and not cause abrasions. Shoes should be 10-15 mm longer than the foot. It is not recommended to wear tight and narrow shoes, as this can lead to foot deformation, limited joint mobility, and impaired blood circulation and innervation.

Heel height is one of the design features of shoes that affect the musculoskeletal system of the foot. Wearing shoes with high heels (7 cm or more) leads to shortening of the calf muscles, relaxation of the anterior muscles of the lower leg and ligaments of the foot. As a result, the leg becomes extremely unstable due to the movement of the center of gravity forward, and the center of support - on the bent toes and heel. This is due to the fact that the footprint of shoes with high heels is 30-40% less than that of shoes with low heels. Often this leads to tucking of the foot, sprains, and dislocations of the ankle joint. Such shoes are especially dangerous in winter. High-heeled shoes contribute to scoliosis, change the normal shape of the pelvis, and lead to displacement of internal organs and the appearance of pain. The rational height of the heel, which provides optimal muscle balance between the flexors and extensors of the foot, cushioning when walking and maintaining the arch of the foot, is 20-30 mm for men, 20-40 mm for women, and 10-30 for children (depending on age). XNUMX mm. In this case, the toe of the shoe must correspond to the width and outlines of the front edge of the foot.

Shoes should be soft, light, water-repellent, not change shape and size after wetting and drying. In the conditions of a cold and average climatic zone, you need to wear shoes made of low heat-conducting materials.

The foot of an adult during 1 hour at rest releases up to 3 ml of sweat, and during physical work - about 8-12 ml. Moisture, accumulating in shoes, irritates the skin, contributes to the appearance of scuffs, maceration of the epidermis, the occurrence of various skin diseases. Therefore, shoes intended for the summer period should provide ventilation of the intra-shoe space due to the physical properties of the materials (breathability, hygroscopicity, etc.), as well as due to design features (perforation of the top, the presence of open areas, etc.), which helps to avoid overheating feet and accumulations of sweat. The best material for summer shoes is genuine leather. Shoes are also made from artificial and synthetic materials.

The child's shoes should not hamper the movement of the foot, especially the fingers. Tight shoes retard the growth of the foot, deform it, cause scuffs, and impede normal blood circulation. Shoes that are too loose can also cause scuffs. Therefore, when designing shoes for children, it is necessary to take into account the features of the children's foot: the footprint should be ray-shaped with a wide toe, raised top, a straight inner edge and a recess for the heel and metatarsophalangeal part. Shoes for young children should be well fixed on the foot.

The correct formation of the foot depends on the heel part of the shoe (heel and heel), so the heel of children's shoes is made especially strong, hard and stable.

Author: Antonova O.A.

<< Back: Patterns of growth and development of the child’s body (Basic patterns of growth and development. Age periodization. Acceleration of growth and development. Age-related anatomical and physiological characteristics. Hygiene of the teaching and educational process at school. Hygienic foundations of students’ daily routine)

>> Forward: Patterns of ontogenetic development of the musculoskeletal system (Features of the functions and structure of the musculoskeletal system. Types and functional characteristics of muscle tissue in children and adolescents. Growth and work of muscles. The role of muscle movements in the development of the body. Peculiarities of growth of the skull bones. Growth of the spine. Spine of an adult and a child. Development of the chest. Features development of the pelvis and lower extremities. Skeleton of the lower extremities. Development of bones of the upper extremities. The influence of furniture on posture. Hygienic requirements for school equipment)

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