What is basal and supplementary metabolism? Basic metabolism. Calorie calculator for weight loss and weight gain. The concept of anatomy and physiology as scientific and educational disciplines

The level of metabolism in a person's natural life is called general exchange. When performing physical and mental labor, changing posture, emotions, and after consuming food, metabolic processes become more intense. The muscles most involved in this process contract. Moreover, the state of skeletal muscles mainly affects the intensity of metabolism in some other physiological conditions. Thus, even when solving a mathematical problem, the tonic tension of the skeletal muscles increases. At the same time, in the cells of the central nervous system themselves, the activity of metabolic processes changes, but not to such an extent as to significantly affect the level of energy consumption of the whole organism. At the same time, if mental work is accompanied by emotional stress, the exchange is activated to a greater extent. This is due to an increase in the formation of a number of hormones that enhance metabolic processes.

Specific dynamic action of food

An increase in metabolism is observed for a fairly long time (up to 10-12 hours) after eating. In this case, energy is spent not only on the actual process of digestion, secretion, motility, absorption). It turns out the so-called specifically dynamic action of food. It is mainly due to the activation of metabolic processes by digestive products. This effect is greatest when protein is supplied. After just 1 hour and over the next 3-12 hours (the duration depends on the amount of food consumed), the activity of energy production processes increases to 30% of the level of basal metabolism. With the intake of carbohydrates and fats, this increase is no more than 15%.

Effect of temperature

The intensity of metabolic processes also increases when the ambient temperature deviates from a comfortable level. The greatest changes in metabolic rate occur with decreasing temperature, since in order to maintain a constant body temperature, energy of other types is converted into heat.

Energy exchange during work

The greatest increase in energy consumption is due to skeletal short-lived muscles. Therefore, under normal conditions of existence, the level of metabolic processes primarily depends on a person’s physical activity. The adult population can be divided into five groups according to the level of general metabolism. The classification is based on the intensity of physical labor, nervous tension that arises during labor processes, individual operations, and a number of other features. As new types and forms of labor activity related to technological progress are introduced and spread, labor intensity groups must be reviewed, clarified and supplemented. Five groups of workers have been identified:

1-a - predominantly mental erasable;

2-a - light physical labor;

3rd - moderate physical labor;

4-a - heavy physical labor;

5-a - especially heavy physical labor.

The need for energy is increased in individuals whose work is characterized not only by physical, but also by neuropsychic stress. Moreover, in modern conditions its importance in all labor processes is increasingly increasing.

In women, due to the lower intensity of metabolic processes and lower muscle mass, the energy requirement is approximately 15% lower than in men.

When determining the energy needs of the adult working population, it is considered appropriate to make all calculations for three age categories: 18-29, 30-39, 40-59 years. The basis for this was some age-related metabolic features. Thus, at 18-29 years of age, the processes of growth and physical development are still ongoing. From the age of 40, and especially after 50, catabolism begins to prevail over anabolism.

When developing criteria for energy requirements for the population aged 18 to 60 years, the ideal body weight was conditionally determined: for men it is 70 kg, for women - 60 kg. Energy requirements can be calculated per 1 kg of average ideal body weight. The energy requirement per 1 kg of ideal weight for men and women is almost the same and is: for the 1st group of labor intensity - 167.4 kJ (40 kcal), for the 2nd - 179.9 kJ (43 kcal), for 3 1st - 192.5 kJ (46 kcal), for 4th - 221.7 kJ (53 kcal), for 5th - 255.2 kJ (61 kcal).

Regulation of energy metabolism

The body must constantly coordinate the metabolic needs of the whole organism with the needs of its individual organs and cells. This is achieved through the distribution of absorbed nutrients between them, as well as the redistribution of substances from the body’s own depots or those formed in biosynthesis processes.

At the level of individual cells and pieces of organs, it is possible to identify the presence of local mechanisms for regulating the process of energy formation. Thus, during the performance of muscular work, the beginning of muscle contraction triggers the processes of resynthesis of the used ATP (see section 1 - “Skeletal muscles”).

Regulation of energy production processes in the body as a whole is carried out by the autonomic nervous and endocrine systems, with the latter predominant. Main regulators - thyroid hormones - thyroxine and G3, as well as A adrenal glands, stimulating these processes. Moreover, under the influence of these hormones there is also a redistribution of metabolites that are used for the formation of energy. So, during physical activity, glucose and fatty acids enter the blood from the liver and fat depots, which are used in the muscles.

The hypothalamus plays a special role in regulation, through which neuro-reflex (autonomic nerves) and endocrine mechanisms are realized. With their help, the participation of higher parts of the central nervous system in the regulation of metabolic processes is ensured. You can even detect a conditioned reflex increase in the level of energy production. Thus, in an athlete before a start, in a worker before performing the labor process, the exchange is activated. The hypnotic suggestion of performing heavy muscular work can lead to an increase in the level of metabolic processes.

Hormones of the hypothalamus, pituitary gland, pancreas and other endocrine glands affect both the growth, reproduction, development of the body, and the ratio of the processes of anabolism and catabolism. In the body, the activity of these processes is in a state of dynamic equilibrium, but at certain moments in real life, one of them is likely to prevail. (These processes are discussed in more detail in the biochemistry course.)

Research methods

Methods for assessing the body's energy balance are based on two main principles: direct measurement of the amount of heat released (direct calorimetry), and indirect measurement - determination of the amount of oxygen absorbed and carbon dioxide released (indirect calorimetry).

Most often used methods of indirect calorimetry. In this case, the amount of oxygen absorbed and carbon dioxide released is first determined. Knowing their volumes, it is possible to determine the respiratory coefficient (RC): the ratio of released CO2 to absorbed 02:

Based on the DC value, one can indirectly estimate (there are corresponding tables) the oxidation of the product, since depending on this, different amounts of heat are released. Thus, during the oxidation of glucose, 4 kcal1g of heat is released, fats -9.0 kcal1g, proteins -4.0 kcal1g (these values ​​characterize the energy value of the corresponding nutrients). The dependence of DC on the product oxidation is determined by the fact that during the oxidation of glucose, the same number of 02 molecules is used to form each CO2 molecule (DC = 1.0). Due to the fact that in the structure of fatty acids there are fewer 02 atoms per CO2 atom than in carbohydrates, during their oxidation the DC is 0.7. When consuming protein foods, the DC is 0.8.

However, when using the indirect calorimetry method, it is necessary to take into account that in real human life conditions, as a rule, mixed ingredients are oxidized. For practical use, special tables have been developed, with the help of which the amount of released energy, that is, the intensity of metabolic processes, can be determined by the amount of oxygen absorbed per unit of time and the value of DC.

Age and gender characteristics of energy metabolism

During the period of ontogenetic development, metabolic processes undergo significant changes. Until the end of puberty (Table 15), anabolic processes predominate.

Table 15. Age-related changes in general and basal metabolism

Age	General exchange, kcal1dobu	BX
		kcal1dobu	kcal1m 1dobu	kcal1kg1dobu
1 day
1 month
1 year
3 years
5 years
10 years
14 years
Adults

Since a large amount of energy is consumed to ensure age-related development, the level of basal metabolism, calculated both per unit of mass and body surface, is sharply increased. The highest rates are during the first years of life, when the basal metabolism is increased by 2-2.5 times compared to that of adults. With aging, catabolic processes predominate, which is accompanied by a gradual decrease in basal metabolism. Moreover, at all age periods, the basal metabolic rate in women is lower than in men. For example, in men aged 40 years, its average value is 36.3 kcal1m21 year, in men aged 70 - 33 kcal1m21 year; in women it is 34.9 and 31.7 kcal1m21year, respectively.

All food substances have a certain amount of energy. The body is called an energy transformer, because specific transformations of nutrients constantly occur in it, leading to the release of energy and its transition from one type to another. The relationship between the amount of energy received from food and the amount of energy expended is called energy balance of the body. To study it, it is necessary to determine the energy value of food.

Studies have shown that each gram of polysaccharides and proteins provides 17.2 kJ. When a gram of fat breaks down, 38.96 kJ is released. It follows that the energy value of different food products is not the same and depends on what nutrients the product contains. So, for example, the energy value of nuts turns out to be equal to 2723.5 kJ, butter - 3322.2 kJ, etc. The energy value of nutrients does not always coincide with their physiological value, because the latter is still determined by the ability to assimilate. Nutrients of animal origin are absorbed better than those of plant origin.

The amount of energy released in the body depends on the chemical transformations of substances in it, i.e., on metabolic processes. It follows that the amount of heat generated by the body can serve as an indicator of metabolism. Determining the amount of heat, i.e., the number of calories released by the body, gives the entire amount of energy transformations in the form of the final thermal result. This method of determining energy is called direct calorimetry. Determination of the number of calories by direct calorimetry is carried out using a calorimetric chamber, or calorimeter.

All these determinations can be made much more simply by studying gas exchange. Determining the amount of energy released by the body by studying gas exchange is called indirect calorimetry. Knowing that the entire amount of energy released in the body is the result of the breakdown of proteins, fats and carbohydrates, knowing also how much energy is released during the breakdown of these substances, and how much of them has undergone breakdown over a certain period of time, we can calculate the amount of energy released.

A distinction is made between general metabolism and basal metabolism. Basic exchange is the energy expenditure of the body under resting conditions associated with maintaining the minimum level of metabolic processes necessary for the functioning of cells. Basal metabolism is determined in a state of muscle rest - lying down, 12 - 16 hours after eating at a temperature of 18 - 20°C. Under these conditions, energy is spent on heart function, breathing, maintaining body temperature, etc. But this energy expenditure is small. The main costs in determining basal metabolism are associated with biochemical processes that always take place in living cells. The basal metabolic rate ranges from 4,200 to 8,400 kJ per day for men and from 4,200 to 7,140 kJ for women. On average, in a middle-aged person, the basal metabolism is 4187 J per 1 kg of weight per hour or 7140 - 7560 thousand J per day. In children 8–9 years old, the basal metabolism is 2–2.5 times higher than in an adult.

The smaller the child, the more energy is spent on his growth. Thus, at the age of 3 months, energy consumption is 36%, at 6 months – 26%, 10 months – 21% of the total energy value of food.

In preschool and primary school age, there is a correspondence between the intensity of the decrease in basal metabolism and the dynamics of growth processes: the greater the rate of relative growth, the more significant the changes in resting metabolism.

The basal metabolic rate in girls is slightly lower than in boys. This difference begins to appear in the second half of the first year of life.

The second component of the body's energy expenditure after the main metabolism are the so-called adjustable energy costs. They correspond to the need for energy used for work above the basal metabolism. Any type of muscular activity, even changing body position (from a lying position to a sitting position), increases the body's energy consumption. The change in energy consumption is determined by the duration, intensity and nature of muscle work. The more intense the muscle load, the more significant the increase in metabolism. In this regard, workers of different professions spend different amounts of energy per day (from 12,600 to 21,000 kJ). Mental work causes a slight increase in metabolism: only 2 - 3%. Any emotional excitement inevitably leads to an increase in metabolism. Metabolism also changes under the influence of food intake. After eating, metabolism increases by 10–40%. The effect of food on metabolism does not depend on the activity of the gastrointestinal tract; it is due to the specific effect of food on metabolism. In this regard, it is customary to talk about the specific dynamic effect of food on metabolism, meaning by this its increase after eating.

In conditions of complete rest, a person expends a certain amount of energy. This expense is due to the fact that in our body there is a continuous expenditure of energy associated

with his life activity. A large amount of energy is spent, which, when contracting, produces significant work, the kidneys, where the process of urine formation continuously occurs, the respiratory muscles, which regularly contract, the liver, where the processes of bile formation take place, and all other organs and tissues of a living organism.

The amount of energy that the body spends at complete rest, on an empty stomach, i.e. 12-16 hours after eating, and at a temperature of 18-20°, is called basal metabolism.

Basic metabolism is determined by the method of indirect calorimetry, i.e., the study of gas exchange.

The average basal metabolic rate for an adult healthy person is 1 large calorie per 1 kg of weight for 1 hour.

For a person weighing 70 kg, the basal metabolic rate will be 70×24 = 1680 large calories. This is the amount of energy that is expended to ensure the vital functions of the body. Basal metabolism depends on the gender, age, height and weight of a person. Men have a higher basal metabolic rate than women of the same weight.

The amount of basal metabolism per 1 kg of body weight in children is greater than in an adult, but heat generation decreases with age. The decrease in heat generation continues for up to 20 years. From 20 to 40 years, heat generation does not change, and after 40 years, it decreases again.

Studies have shown that in different animals the value of basal metabolic rate, calculated per 1 kg of weight, fluctuates quite sharply: the smaller the animal, the greater the basal metabolic rate per 1 kg of weight. 1 kg weight. Meanwhile, when calculating not per weight, but per unit body surface area, it turned out that in almost all animals the amount of energy spent per 1 m 2 of body surface is approximately the same or varies within insignificant limits. This can be seen from mog 10.

TABLE Basic metabolism when calculated per 1 m 2 body surface and per 1 kg of body weight in different animals and humans

This pattern is called the surface law, but it is not absolute. However, this law makes it possible to establish the most convenient measure of basal metabolic rate for comparison: the number of calories given per unit of body surface per day.

Changes in basal metabolism are observed when the activity of the endocrine glands is disrupted. For example, increased thyroid function leads to an increase in basal metabolism, which is often measured for diagnostic purposes.

Energy consumption during operation

The basal metabolic rate for a healthy adult is on average 1,700 calories. During muscular work, energy consumption increases rapidly: the harder the muscular work, the more energy a person spends.

When working, it is important to calculate the efficiency factor, i.e. the ratio of the work done to the amount of energy expended. The study showed that the efficiency rate in humans is on average 20%; during training it increases and reaches 25-35%.

Based on the amount of energy expended, people of different professions can be divided into several groups.

First group. Work in a sitting position that does not require large muscle movements: clerical workers, lithographers, etc., -2200-2400 large calories.

TABLEEnergy consumption per day of persons of different professions

Professions	Energy consumption per day in large calories
Metal turners and instrumentals boxes	3300
Blacksmiths	3700 — 4000
Rolling shop workers	3500 — 4100
Foundry workers	4000 — 4500
Carpenters	4500
Brick carriers	5400
Masons, masons	6000
Tractor drivers	3000
Pahari….	4700 — 5000
Mowers:
Hand mowing	7200
Machine	3600
Sheaf knitters	5300-6500
Medical students	2800-3000
Students 8-11 years old	1900
12-14	2400

Second group. Work in a sitting position - tailors, mechanics for delicate work - 2600 2800 large calories.

Third group. Moderate muscle work: bootnicknames, postmen, doctors, laboratory workers - 3000 large calories.

Fourth group. Intense muscular work: metal workers, painters, carpenters - 3400-3600 large calories.

Fifth group. Heavy physical labor - 4000 large calories or more.

Sixth group. Very hard work - 5000 large calories or more.

Mental work uses very little energy. In the case when mental work is combined with movement and muscle load, for example in an artist or speaker, energy consumption increases.

In recent years, energy expenditure in people of different professions has been studied in detail. These data are provided in table

REGULATION OF METABOLISM AND ENERGY

When studying the effect of enhancing the nerve of the heart And . P. Pavlov showed that the reinforcing nerve has a trophic effect on the heart muscle, that is, it changes the intensity of the metabolism occurring in it.

The doctrine of the trophic function of the nervous system was widely developed by Soviet physiology. The role of the autonomic nervous system in the regulation of metabolism and energy is shown. This action is carried out by the influence of the nervous system on energy, both directly and through physiologically active hormones.

Energy is influenced by different parts of the nervous system. If an animal is injected into the bottom of the fourth ventricle of the medulla oblongata, a sharp increase in blood sugar occurs and sugar begins to be excreted in the urine. The activity of the diencephalon is associated with protein metabolism.

Energy is influenced by the cerebral hemispheres. Experiments conducted in the laboratory of K. M. Bykov showed a close connection between the activity of the cerebral cortex and metabolism and energy.

In observations of workers, it was found that if a worker sits quietly on a chair in the workshop, and other members of his team are working, the metabolism and energy consumption of the sitting worker also increases sharply. It is clear that this can only happen under the influence of the cerebral cortex.

In another observation, the basal metabolic rate of a worker was determined, and work noise from the workshop reached the room where this determination was made. Under these conditions, the basal metabolism increased by 15-30%. On a non-working day, such an increase was not observed.

As already mentioned, metabolism is influenced by hormones of the endocrine glands. The adrenal hormone - adrenaline, and the pancreatic hormone - insulin, have an effect on carbohydrate metabolism. The metabolism of fats and proteins is influenced by the hormones of the thyroid gland, pituitary gland, and gonads.

The release of hormones is regulated by the nervous system, so hormones in a healthy body act in the same direction as at the moment. Nervous and hormonal influences represent a single mechanism.

Various metabolic disorders that arise when the activity of one or another endocrine gland is disrupted will be discussed in detail in the chapter on the endocrine glands.

Article on the topic Basic metabolism in humans

Metabolism and energy is a set of physical, chemical and physiological processes of absorption of nutrients in the body with the release of energy. In metabolism (metabolism), there are two interrelated but multidirectional processes - anabolism and catabolism. Anabolism is a set of processes of biosynthesis of organic compounds, components of cells, organs and tissues from absorbed nutrients. Catabolism is the process of breaking down complex components into simple substances that provide the energy and plastic needs of the body. The vital activity of the body is provided by energy due to anaerobic and aerobic catabolism of proteins, fats and carbohydrates supplied with food.

Basic exchange is the amount of energy that the body spends at complete muscular rest, 12–14 hours after eating and at an ambient temperature of 20–22° C. Basic metabolism maintains the life of the body at the lowest level of activity of the nervous system, heart, respiratory apparatus, digestion, endocrine glands, excretory processes, rest of skeletal muscles. Even in conditions of complete rest, metabolism in cells and tissues does not stop - the basis of life of the body. The indicator of basal metabolism is heat production in kcal per 1 hour per 1 kg of body weight and is equal to 1 kcal.

The leading role in metabolism belongs to the functional state of the nervous system, its regulation of the level of metabolism in organs and tissues, maintaining the relative constancy of the composition of proteins, the chemical composition of blood, temperature, etc., relatively independently of changes in the external environment, under different living conditions. The activity of the endocrine glands also significantly affects the basal metabolism. For example, basal metabolism increases when the function of the thyroid gland increases and, conversely, decreases when the functions of the thyroid gland and pituitary gland decrease. With an increase in body temperature on the HS, the basal metabolism increases on average by 10%. In cold climates, basal metabolism increases, and in hot climates it decreases by 10 - 20%. During sleep, as a result of relaxation of skeletal muscles, it decreases to 13%. During fasting, the basal metabolism decreases. From 20 to 40 years, the basal metabolism is maintained at approximately the same level, and then gradually falls: in men to 7%, and in women up to 17%.

General metabolism- occurs under normal living conditions. It is significantly higher than the basal metabolism and depends mainly on the activity of skeletal muscles, as well as an increase in the activity of internal organs. The kilocalories expended in excess of the basal metabolism are called motor calories. The more intense the muscle activity, the more motor calories and the higher the overall metabolism. So, if the daily basal metabolism in a person weighing 70 kg averages 1680 kcal (7056 kJ), then with little physical labor it equals 2200-2800 kcal (9240-11760 kJ), with mechanized labor - 2800-3600 kcal (11760-15120 kJ), heavy physical labor - 3600-4500 kcal (15120-18900 kJ), and for very hard physical labor 4500-7200 kcal (18900-31240 kJ). The average daily energy consumption of physical education students is 4000 kcal (16800 kJ). Energy consumption in kcal per 1 kg of body weight during sleep - 0.93; lying without sleep - 1.1; reading aloud - 1.5; typing - 2; homework - 1.8-3.0; walking on a flat road at a speed of 4.2 km per hour - 3.2; calm running on a flat road - 6.0; speed running 100 w - 45.0; skiing at a speed of 12 km per hour - 12.0; rowing - 2.5-6.0; cycling - 3.5-9.0.

During mental work, the overall metabolism increases slightly - by 2-3%, and if mental work is accompanied by muscle activity - by 10-20%.

A significant increase in metabolism also occurs during the digestion of food, which is referred to as its specific dynamic action. Since the digestion of proteins requires a particularly large expenditure of energy, the specific dynamic effect of proteins is especially great. On average, after eating protein foods, basal metabolism increases by 30% - 37%, and after eating fats and carbohydrates by an average of 4% - 6%.

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With each contraction of the human heart, the left and right ventricles expel approximately 60–80 ml of blood into the aorta and pulmonary arteries, respectively; this volume is called systolic or stroke volume

General characteristics and age-related characteristics of the respiratory system
The human respiratory system consists of the nasal cavity, larynx, trachea, bronchi and lungs. Depending on their function, the respiratory organs are divided into airways and respiratory or respiratory

Structure, functions and age-related characteristics of the airways (nasal cavity, larynx, trachea, bronchi)
The airways begin with the upper respiratory tract - the nasal passages, nasal cavity and nasopharynx, which directs air flow through the larynx to the trachea. In its lower part

Structure, functions and age-related characteristics of the lungs
The right and left lungs occupy 4/5 of the chest, each located in an independent serous pleural cavity. Inside these cavities, the lungs are fixed by bronchi and blood vessels

Breathing regulation
There is nervous and chemical regulation of breathing. Nervous regulation of breathing is caused by the influx of centripetal impulses from the receptor to the respiratory center located in the medulla oblongata.

Mechanism of inhalation and exhalation
Thanks to the rhythmic contraction of the diaphragm (16-18 times per minute) and other respiratory muscles (external intercostal muscles, muscles of the shoulder girdle, neck), the volume of the chest either increases (with inhalation) or

General characteristics and age-related characteristics of the digestive system
Anatomically, the digestive system consists of the digestive tract or canal and the digestive glands. The digestive tract is a tube the length of which in an adult

Digestion in various parts of the gastrointestinal tract
Digestion is the process of physically and chemically processing food and converting it into simpler and more soluble compounds that can be absorbed, transported in the blood, and absorbed.

Absorption of food digestion products
Absorption is the process of various substances entering the blood and lymph from the digestive system. Absorption is a complex process involving diffusion, filtration and osmosis.

Anatomy and physiology and age-related characteristics of the digestive glands
The liver is the largest digestive gland and has a soft consistency. The weight of an adult is 1.5 kg. The liver is involved in the metabolism of proteins, carbohydrates, fats, and vitamins. Among many

Protein metabolism
Proteins are the main plastic material from which the cells and tissues of the body are built. They are an integral part of muscles, enzymes, hormones, hemoglobin, antibodies and other vital

Lipid metabolism
The physiological role of lipids (neutral fats, phosphatides and sterols) in the body is that they are part of cellular structures (plastic value of lipids) and are

Exchange of water and mineral salts
Water is an integral part of all cells and tissues and is found in the body in the form of salt solutions. The body of an adult is 50–65% water, in children it is 80% or more. In different orgs

Vitamins and their importance for the body
Vitamins are organic compounds found in animal and plant products and are absolutely necessary for normal metabolism. Their composition and structure are very diverse. Vitamins

Energy exchange
The body must maintain an energy balance of energy intake and expenditure. Living organisms receive energy in the form of its potential reserves accumulated in chemical bonds

Heat exchange
In the human body, two processes continuously occur - heat production and heat loss, and under resting conditions, the rate of heat production is normally equal to the rate of heat loss. This is called a thermal ball

General characteristics of the excretory system
Excretion is the process of freeing the body from metabolic products that cannot be used by the body, foreign and toxic substances, excess water, salts, and organic compounds. Up to 75% withdrawal

Anatomy, physiology and age-related characteristics of the kidneys
Human kidneys (paired organs) are bean-shaped, weighing 120-200 g each. The dimensions of the kidney are 12x6x3 cm. The kidneys are located on the posterior abdominal wall on the sides of the spine at the level of the XII chest

Mechanisms of urine formation
During the day, a person consumes approximately 2.5 liters of water, including 1500 ml in liquid form and about 650 ml with solid food. In addition, in the body, in the process of breakdown of proteins, fats and carbohydrates, the image

Regulation of urine formation
Regulation of urine formation is carried out by the neurohumoral pathway. The highest subcortical center for the regulation of urine formation is the hypothalamus. Impulses from kidney receptors by sympathies

Anatomy, physiology and age-related features of the urinary tract (ureters, bladder, urethra)
The renal pelvis, gradually narrowing, passes into the ureter. The human ureter is a cylindrical tube with a diameter of 6-8 mm, a length of 25-35

General characteristics and functions of the skin
The skin covers almost the entire surface of the human body and is one of the largest organs. Its total surface in an adult is 1.5-2 m2, the mass is 4-6% of body weight, the volume is about

Skin structure
The skin consists of three layers: the outer layer - epithelial, or epidermis, originating from the ectoderm, and connective tissue, or dermis, originating from the mesoderm (Fig. 22). Beneath the dermis is gi

Leather derivatives
Hair. Almost all the skin is covered with hair. Exceptions include the palms, soles, transitional part of the lips, glans penis, and labia minora. The largest number of hairs is usually on the head. In

Age-related skin features
In newborns, the ratio of skin weight to body weight is 19.7%, in adults it is 17.7%. The dermis of newborns is 1.5-3 times thinner compared to adults, and the subcutaneous tissue is approximately 5 times more per unit

During physical and mental work, after eating, when changing body posture, and emotions, metabolic processes become more intense. The level of exchange under normal conditions is called general exchange. Its increase depends on the intensity of muscle contraction. Mental activity also matters, and if it is accompanied by emotions, then the exchange is activated to a significant extent. This is explained by the activation of the processes of creating a number of hormones that enhance metabolic processes.
Specifically dynamic effects of food. An increase in metabolism is observed for many hours after eating (up to 10-12 hours). In this case, energy is spent not only on the digestion process itself (secretion, motility, absorption). The so-called specifically dynamic effect of food appears. It is largely determined by the activation of the processes of exchange of digestive products. This effect is especially pronounced when proteins are supplied. Already after 1 hour and over the next 3-12 hours (the duration depends on the amount of food taken), with the intake of proteins, the activity of energy production processes increases to 30% of the level of total metabolism. With the intake of carbohydrates and fats, this increase is no more than 15%.
Effect of temperature. The intensity of metabolic processes increases when the ambient temperature deviates from a comfortable level. This is most evident when the temperature decreases, since in order to maintain a constant body temperature, energy of other types is converted into heat.
Energy exchange during work. The greatest increase in energy consumption is caused by contraction of skeletal muscles. Therefore, the level of metabolic processes primarily depends on a person’s physical activity. The adult population can be divided into five groups according to the level of general metabolism:
1st, engaged primarily in mental work;
Note:
1) the need of a woman during pregnancy for a period of 5-6 months is on average 12,133 kJ (2900 kcal), 2) the need of breastfeeding women is on average 13,388 kJ (3200 kcal).
2 - I - engaged in light physical labor;
3rd - those who perform moderate physical work;
4 - and - engaged in heavy physical labor;
5 - and - are engaged in very hard physical labor.
The classification is based on the intensity of physical labor, the degree of nervous tension that arises during the performance of labor processes, individual operations, etc. As new types and forms of labor activity related to technical progress are introduced and spread, the classification should be revised, clarified and supplemented.
Due to the less intense dynamics of metabolic processes and lower muscle mass, a woman’s body’s need for energy is approximately 15% lower than that of men. The need for energy increases in people whose work is accompanied not only by physical, but also by neuropsychic stress. Moreover, in modern conditions the importance of the last factor is increasing. When establishing the energy needs of the adult working population, it is considered appropriate to carry out all calculations for three age categories: 18-29 years, 30-39 years, 40-59 years. The basis for this is some age-related metabolic features. Thus, at the age of 18-19 years, the processes of growth and physical development are still ongoing. Starting from the age of 40, and especially after 50, the processes of catabolism begin to dominate over the processes of anabolism. When developing criteria for energy requirements for the population aged 18 to 60 years, the conventionally accepted ideal body weight is taken into account: for men it is 70 kg, for women it is 60 kg. The energy requirement can be calculated per 1 kg of ideal body weight for men and women almost equally and amounts to 167.4 kJ (40 kcal) for the first group, 179.9 kJ (43 kcal) for the second group, and 192.5 kJ for the third group ( 46 kcal), for the fourth - 221.7 kJ (53 kcal), for the fifth - 255.2 kJ (61 kcal).