Work metabolism, energy expenditure of the body during various types of labor. Working check
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 number of spends energy, which, contracting, produces significant work, the kidneys, where continuously the process is underway urine formation, respiratory muscles that regularly contract, the liver, where bile formation processes 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 is equal to that of an adult healthy person 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 various 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 coefficient useful action, 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 last 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 trophic function nervous system 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, basal metabolism increased by 15-30%. On a non-working day, no such increase was 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
How does it enter the body? free energy, i.e. energy that can be used in the body to perform work?
Free energy comes from food. It is accumulated in the chemical bonds of proteins, fats and carbohydrates. To release this energy, nutrients first undergo hydrolysis and then oxidation under anaerobic or aerobic conditions.
What is the name of the process that releases energy in the body?
Dissimilation (catabolism), i.e. the breakdown of chemical compounds in the body. In this case, decay products are formed and energy is released.
What nutrients provide energy in the body?
Carbohydrates, fats, proteins.
Describe the stages of free energy release in the body.
1st stage release– is realized in the process of hydrolysis of food in the gastrointestinal tract, while a small part of free energy is released – 0.5-1%. It cannot be used for bioenergy, because it is not accumulated in macroergs (ATP). She only turns into thermal energy (primary heat), which is used to warm the body.
Stage 2 release– the process of anaerobic oxidation, in which approximately 5% of the total free energy is released during the oxidation of glucose to lactic acid. This energy is accumulated in the form of ATP and is used to perform useful work, ultimately turning into thermal energy ( secondary heat).
Stage 3 release(basic) - approximately 94% of all energy that is released in the body as part of the Kreps cycle. It oxidizes pyruvic acid (a product of glucose oxidation) and acetyl coenzyme A (a product of amino and fatty acid oxidation). During aerobic oxidation, most of the free energy (50-55%) is accumulated in ATP. The rest is lost as heat ( primary heat). Free energy accumulated in ATP is used to perform useful work, ultimately turning into thermal energy ( secondary heat).
How, in principle, can one assess the intensity of energy production in the human body?
Since all the free energy released in the body during oxidation nutrients, eventually turns into thermal energy was made conclusion that to parameterize the intensity of energy production one should measure the amount of thermal energy in kcal (4.2 kJ) produced by the body per unit time.
Name the types of energy metabolism in humans.
1. Basic metabolism. 2. General, or working, exchange.
What is basal metabolic rate?
Main, or standard, metabolism is the minimum level of energy production in a waking person. To determine the value of the basal metabolic rate, it is necessary to comply with a certain standard conditions, forming such a functional status of a awake person in which his energy expenditure becomes minimal, while the person’s energy production also becomes minimal.
Describe the standard of conditions that ensure that a person’s energy expenditure is brought to the minimum acceptable level.
The minimum level of energy expenditure in a awake person is observed Therefore, the determination of a person’s basal metabolism is carried out in the morning after sleep, lying in bed, in conditions of physical and mental rest, temperature comfort, on an empty stomach, 10-12 hours after the last meal. Often when determining the basal metabolic rate 48 hours before hardware measurement, the person is transferred to a protein-free diet.
What is basal metabolic energy used for?
To ensure life activity in conditions of physiological rest. At the same time, 27% of energy is spent on ensuring the functioning of the liver, brain – 19%, heart – 7%, kidneys – 10%, muscles – 18%, other organs – 19%. Total – 100%.
What is the basal metabolic rate?
On average, 1700 kcal/day - according to established tradition, it is used as a time unit when assessing the parameters of energy metabolism in humans day. The basal metabolic rate for each person is almost constant those. this is some individual constant.
What determines the basal metabolic rate?
From the floor(in men the basal metabolism is higher, in women it is 10-15% less), by age(the older the age, the lower the basal metabolic rate), on height and body weight, i.e., on the surface area of the body. The larger the surface area of the body, the more intense the heat transfer, the more energy is produced to maintain a stable temperature of the internal environment of the body, the greater the basal metabolic rate.
For what purpose is the basal metabolic rate determined in the clinic?
To assess the functional state of the thyroid gland. With hyperfunction of the thyroid gland (excessive production of hormones T 3, T 4), the basal metabolic rate increases significantly; with hypofunction, it decreases. Therefore, if it is not possible to determine the level of thyroid hormones in the blood, the basal metabolic rate is determined.
The basal metabolic rate is a guideline when calculating the amount of optimal physical activity during industrial, sports and other activities of a particular person.
What is proper basal metabolic rate?
Taking into account the fact that the value of the basal metabolic rate is “different” for everyone, depending on gender, age, and body surface area, the question arises - how to estimate the value of the basal metabolic rate of a particular person when conducting hardware (instrumental) measurements. In this case, before taking the measurement, calculate using special tables size proper basal metabolism, reflective due parameters of a person’s basal metabolism, taking into account his gender, age, and body surface area. Let's assume that the required basal metabolic rate, calculated from the tables, is 1800 kcal/day. Taking into account the 10% deviation rule, the normal value of a person’s basal metabolic rate is 1800 + 180 kcal/day. We carry out a hardware measurement and get the result - a person’s basic metabolism is 1700 kcal/day. It can be seen that the result obtained falls within the range of permissible deviations in the value of the proper basal metabolism (1620-1980 kcal/day), calculated from the tables. Conclusion: the obtained value of basal metabolism with a hardware measurement of 1700 kcal reflects the normal level of human bioenergy under the conditions of the standard for measuring basal metabolism.
What is general, or working, exchange?
This is the energy expenditure of the body in real life, usually associated with the performance of some background behavioral activity, professional work activity.
What components does the general (working) exchange consist of?
From the magnitude basal metabolic rate (1), work increase(2), reflecting an increase in human energy production associated with the need to provide energy for specific labor, i.e., work activity, as well as specific dynamic action of food(3), reflecting an increase in energy production in the body after eating.
By what percentage does energy production in the body increase after eating protein and mixed foods (specific dynamic effect of food)?
After eating protein foods - by 20-30%, mixed foods - 10-12%.
What determines the size of the labor increase, which makes up a significant part of the total (working) exchange?
Depends on the type of labor (work) activity. For persons involved mental work, the amount of the working increase to the basal metabolism (1700 kcal/day) is about 600-800 kcal/day. For persons engaged in light physical work, the working increase to the basal metabolic rate is approximately 1600 kcal/day; for persons engaged in moderate physical work, the working increase is approximately 2300 kcal/day; for persons engaged in heavy physical activity, the working increase can be 3000 and more than kcal/day.
The average daily energy consumption of medical university students is about 3000 kcal/day, for those engaged in light physical work - about 3500 kcal/day, for those engaged in moderate physical work - about 4000 kcal/day, for those engaged in heavy physical work - 4500 or more kcal/day .
Indicate their size and definition in humans. Explain the role of thyroid hormones in the regulation of basal metabolism
Almost half of all the energy produced by catabolism is lost as heat during the formation of ATP molecules. Muscle contraction is an even less efficient process. About 80% of the energy used during muscle contraction is lost as heat and only 20% is converted into mechanical work(muscle contraction). If a person does not do work, then almost all the energy he generates is lost in the form of heat (for example, a person lying in bed). Consequently, the amount of heat production is an exact expression of the amount of metabolism in the human body.
To determine the amount of energy expended by the body, direct and indirect calorimetry are used. The first direct measurements of energy metabolism were carried out in 1788 by Lavoisier and Laplace.
Direct calorimetry involves directly measuring the heat generated by the body. To do this, an animal or person is placed in a special sealed chamber, with water flowing through pipes passing through it. To calculate heat production, data on the heat capacity of the liquid, its volume flowing through the chamber per unit time, and the temperature difference between the liquid entering the chamber and the liquid flowing out are used.
Indirect calorimetry is based on the fact that the source of energy in the body is oxidative processes, in which oxygen is consumed and carbon dioxide is released. Therefore, energy metabolism can be assessed by studying gas exchange. The most common method is the Douglas-Haldane method, in which the air exhaled by the person being examined is collected in a bag made of airtight fabric (Douglas bag) for 10-15 minutes. Then the volume of exhaled air and the percentage of O2 and CO2 in it are determined.
According to the ratio between the amount allocated carbon dioxide and the amount consumed per this period oxygen time - respiratory coefficient (RK) - you can determine which substances are oxidized in the body. DC for the oxidation of proteins is 0.8, for the oxidation of fats - 0.7, and for carbohydrates - 1.0. Each DC value corresponds to a certain choleric equivalent of oxygen, i.e. the amount of heat that is released during the oxidation of a substance for each liter of oxygen absorbed. The amount of energy per unit of consumed 02 depends on the type of substances oxidized in the body. The caloric equivalent of oxygen during the oxidation of carbohydrates is 21 kJ per 1 liter 02 (5 kcal/l), proteins - 18.7 kJ (4.5 kcal), fats - 19.8 kJ (4.74 kcal).
Several physiological parameters related to oxygen consumption can be used to indirectly determine metabolic rate: respiratory rate and ventilation volume, heart rate and minute volume of blood flow all reflect energy expenditure. However, these indicators are not accurate enough.
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The intensity of energy metabolism varies significantly and depends on many factors. Therefore, to compare energy costs different people a conditional standard value was introduced - basal metabolic rate. Basal metabolism is the minimum energy expenditure for a waking body, determined under strictly controlled standard conditions:
- 1) at comfortable temperature(18-20 degrees Celsius);
- 2) in a lying position (but the subject should not sleep);
- 3) in a state of emotional peace, since stress increases metabolism;
- 4) on an empty stomach, i.e. 12-16 hours after the last meal.
Basal metabolism depends on the gender, age, height and body weight of a person. The average basal metabolic rate is 1 kcal per 1 hour per 1 kg of body weight. In men, the basal metabolism per day is approximately 1700 kcal; in women, the basal metabolism per 1 kg of body weight is approximately 10% less than in men; in children it is greater than in adults, and gradually decreases with increasing age.
The daily energy expenditure of a healthy person significantly exceeds the value of the basal metabolism and consists of the following components: basal metabolism; work increase, i.e. energy costs associated with performing a particular job; specific dynamic action of food. The totality of the components of daily energy expenditure constitutes the working metabolism. Muscular work significantly changes the metabolic rate. The more intense the work performed, the higher the energy consumption. The degree of energy expenditure during various physical activities is determined by the physical activity coefficient - the ratio of the total energy expenditure for all types of activity per day to the value of the basal metabolic rate. According to this principle, the entire population is divided into 5 groups.
For people doing light work while sitting, they need 2400 - 2600 kcal per day, those working with greater muscle load, 3400 - 3600 kcal are required for people doing heavy work. muscle work- 4000-5000 kcal and above. In trained athletes, during short-term intense exercise, the amount of working metabolism can be 20 times higher than the basal metabolism. Oxygen consumption at physical activity does not reflect the total energy expenditure, since part of it is spent on glycolysis (anaerobic) and does not require oxygen consumption.
The difference between the need for 02 and its consumption is the energy obtained as a result of anaerobic breakdown and is called the oxygen debt. 0^ consumption remains high even after the end of muscular work, since at this time the oxygen debt is returned. Oxygen is spent on the conversion of the main by-product of anaerobic metabolism - lactic acid into pyruvic acid, on the phosphorylation of energy compounds (creatine phosphate) and the restoration of 02 reserves in muscle myoglobin.
Eating increases energy metabolism (the specific dynamic effect of food). Protein foods increase metabolic rate by 25 - 30%, and carbohydrates and fats - by 10% or less. During sleep, the metabolic rate is almost 10% lower than the basal metabolic rate. The difference between being awake at rest and being asleep is due to the fact that during sleep the muscles are relaxed. With hyperfunction of the thyroid gland, the basal metabolism increases, and with hypofunction it decreases. A decrease in basal metabolism occurs when the functions of the gonads and pituitary gland are insufficient.
During mental work, energy consumption is significantly lower than during physical work. Even very intense mental work, if it is not accompanied by movements, causes an increase in energy expenditure by only 2-3% compared to complete rest. However, if mental activity is accompanied by emotional arousal, energy expenditure can be noticeably greater. The experienced emotional arousal can cause an increase in metabolism by 11-19% over the next few days.
As a first approximation, the working exchange is two to three times higher than the main one. There are empirically calculated average values of daily energy expenditure for people in certain professions. For example, a young man of average height and weight, combining intellectual work and fitness, spends about 3000 kcal per day. However, such an approximate estimate means nothing: for the same job two similar person can spend completely different amounts of energy. This is why one person loses as many extra pounds in a week of training as another person cannot lose in a month with the same load.
The thyroid gland (lat. glandula thyroidea) is an endocrine gland in vertebrates and humans, producing hormones involved in the regulation of metabolism - thyroxine, triiodothyronine, thyrocalcitonin. These hormones contain iodine, so this element is necessary for normal functioning glands.
In an adult thyroid located in the anterior region of the neck, in front of the larynx and in the upper part of the trachea.
The thyroid gland produces a number of hormones that are involved in regulating the processes of growth, development, and tissue differentiation. They increase the metabolic rate and the level of oxygen consumption by organs and tissues.
It is now known that the thyroid gland consists of two lobes connected by a narrow isthmus. This is the largest endocrine gland. In an adult, its mass is 25-60 grams.
Thyroid diseases
Myxedema
Cretinism
Hashimoto's goiter
Thyrotoxicosis
Hypothyroidism
Thyroid cancer
Graves' disease
The parathyroid glands and parathyroid glands are located on the posterior surface of the thyroid gland. There are four of these glands, they are very very small, their total mass is only 0.1-0.13 g. The hormone of these glands regulates the content of salts, calcium and phosphorus in the blood; with a lack of this hormone, the growth of bones and teeth is impaired, and the excitability of the nervous system increases .
Table of contents of the topic "Metabolism and energy. Nutrition. Basic metabolism.":1. Metabolism and energy. Nutrition. Anabolism. Catabolism.
2. Proteins and their role in the body. Rubner wear coefficient. Positive nitrogen balance. Negative nitrogen balance.
3. Lipids and their role in the body. Fats. Cellular lipids. Phospholipids. Cholesterol.
4. Brown fat. Brown adipose tissue. Blood plasma lipids. Lipoproteins. LDL. HDL. VLDL.
5. Carbohydrates and their role in the body. Glucose. Glycogen.
8. The role of metabolism in meeting the energy needs of the body. Phosphorylation coefficient. Caloric equivalent of oxygen.
9. Methods for assessing the body’s energy expenditure. Direct calorimetry. Indirect calorimetry.
Under basal metabolism understand the minimum level of energy expenditure necessary to maintain the vital functions of the body in conditions of relatively complete physical, emotional and mental rest. In a state of relative rest, energy is spent on the functions of the nervous system, the constantly ongoing synthesis of substances, work ion pumps, maintaining body temperature, activity of the respiratory muscles, smooth muscles, heart and kidney function.
Energy consumption of the body increase during physical and mental work, psycho-emotional stress, after eating, and when the ambient temperature drops. In order to exclude the influence of the listed factors on the amount of energy expenditure, the determination of basal metabolism is carried out under standard, strictly controlled conditions: in the morning, in a lying position, with maximum muscle relaxation, while awake, in conditions of temperature comfort (about 22 ° C), on an empty stomach ( 12-14 hours after eating). The values of basal metabolism obtained under such conditions characterize the initial “basal” level of energy expenditure of the body.
For an adult, the average value is basal metabolic rate equals 1 kcal/kg/h (4.19 kJ). Consequently, for an adult man weighing 70 kg, the energy consumption is about 1700 kcal/day (7117 kJ), for women - about 1500 kcal/day. The intensity of the basal metabolic rate is closely related to the size of the body surface, which is due to the direct dependence of the amount of heat transfer on the body surface area. In warm-blooded organisms that have different sizes body, from 1 m2 of body surface the same amount of heat is dissipated into the environment. On this basis it was formulated body surface law, according to which the energy expenditure of a warm-blooded organism is proportional to the size of the body surface.
Table 12.4. Equations for calculating the basal metabolic rate.Basal metabolic values determined by direct or indirect calorimetry methods. Its proper values can be calculated using equations taking into account gender, age, height and body weight (Table 12.4).
Normal values of basal metabolic rate in an adult, it can also be calculated using Dreyer’s formula:
H = W/K A,where W is body weight (g), A is age, K is a constant (0.1015 for men and 0.1129 for women).
Basal metabolic rate depends on the ratio of anabolism and catabolism processes in the body. Predominance in childhood anabolic processes in metabolism over catabolic processes determine higher values of the basal metabolic rate in children (1.8 and 1.3 kcal/kg/h in children 7 and 12 years old, respectively) compared to adults (1 kcal/kg/ h), in which the processes of anabolism and catabolism are balanced in their state of health.
Since heat production indicators, blood pressure and heart rate are interrelated, you can calculate basal metabolic rate and its deviations from the norm according to the following formula:
PO = 0.75 (HR + PP 0.74) - 72,where PO is the percentage of deviation from the norm, HR is heart rate, PP is pulse pressure.
For each age group people are identified and accepted as basal metabolic rate standards. This makes it possible, if necessary, to measure its value in a person and compare the indicators obtained from him with the normative ones. A deviation of the basal metabolic rate from the standard value by no more than +10% is considered within normal limits. More significant deviations in basal metabolism can serve as diagnostic signs of such body conditions as dysfunction of the thyroid gland; recovery after severe and long-term illnesses, accompanied by activation of metabolic processes; intoxication and shock, accompanied by inhibition of metabolism.
Basal metabolic rate varies in different organs and tissues. As energy expenditure at rest decreases, they can be arranged in the following order: internal organs-muscles-adipose tissue.
In humans and animals normal conditions existence is called general exchange.
The average total metabolism in humans is much higher than in animals. Per 1 kg of body weight, an adult consumes up to 3,300,000 kJ during his life, a horse - 685,000, a dog - 690,000, a cow - 592,000 kJ. Of this amount of kJ, a person uses about 5% to restore body weight, a horse and a cow - 33%, a dog - 35% (M. Rubner). Consequently, a person spends approximately 2,900,000 kJ for work and heat generation per kg of mass during his life, which is several times more than in animals.
Metabolism under strictly defined conditions, which makes it possible to compare metabolism in different animals, is called basic.
Basal metabolism - extremely low level metabolism, ensuring human life with muscular and mental rest, on an empty stomach, in the morning, at least 12-14 hours after eating, at normal body temperature and temperature environment about 20-22 degrees.
For each person, the basal metabolic rate is a relatively constant value. The basal metabolism depends on the functional state of the nervous system, age, gender, height and body surface, the physiological state of the body, the time of year, and in animals also on the species and breed.
In animals, the basal metabolism is determined under the following conditions: 1) in a state of relative rest, 2) at a temperature optimal for a given animal species, 3) with the digestive canal relatively free of food.
To compare basal metabolism in different animal organisms, heat production is taken into account in kilojoules per hour per 1 kg of body weight.
The basal metabolism represents the lowest level of energy expenditure to maintain the basic processes of life in cells, tissues and organs, to contract the respiratory muscles, the heart, and the activity of the glands. When determining the basal metabolism, it should be taken into account that most of the thermal energy is released during oxidative processes in the muscles.
The average basal metabolic rate in a healthy middle-aged person is approximately 4.2 kJ per hour per 1 kg of body weight.
Thin people produce 50% more heat per kg of body weight than fat people. However, this difference almost disappears if the calculation is made for 1 m 2 of body surface. This allowed us to assume that the basic metabolism is approximately proportional to the surface of the body and does not depend on the size of the body (Rubner's rule). This pattern was not confirmed. It turned out that metabolism depends not only on the surface, but also on the size of the animal’s body; for example, in a horse, the basic metabolism per 1 m2 is almost 2 times greater than in a rat.
The intensity of metabolism is determined mainly by the activity of the cytoplasm, especially muscle activity, and not by the size of the outer surface, for example, in the first year of life, the weight of a child increases 3 times, and the size of its outer surface sharply decreases (V.N. Nikitin, 1963).
The leading role in regulating the level of basic metabolism in accordance with living conditions belongs to the nervous system.
Age-related, daily, climatic and other changes in basal metabolism
Basal metabolism decreases with age. At all ages, men have a higher basal metabolic rate than women.
During sleep, the basal metabolic rate decreases to 13% due to complete relaxation skeletal muscles. When the body rises by 1°C, the basal metabolism increases by an average of 10%. In hot climates, basal metabolism is 10-20% lower, and, conversely, it is much higher in cold climates. Basic metabolism also depends on the activity of the endocrine glands, for example, with an increase in the function of the thyroid gland, it increases significantly, and with a decrease in the function of the pituitary gland and thyroid gland, it sharply decreases.
The specific dynamic effect of food is that after eating, metabolism increases. Therefore, the basal metabolism is determined before eating food.
The specific dynamic effect is especially great. When proteins enter the body, basal metabolism increases by an average of 30%, and by an average of 4%. Specific dynamic action nutrients depends on the enhancement of oxidative processes by intermediate metabolic products. An insignificant role is played by the increase in activity of the digestive canal after food enters it. Since metabolism is regulated by the nervous system, the specific dynamic action depends on the functions of the nervous system and is regulated by unconditioned reflexes.
In children, the specific dynamic effect of nutrients is less pronounced than in adults.
Eating increases metabolism in a conditioned reflex way.
Energy consumption during operation
The working exchange rate during the day is much higher than the basal exchange rate. Most of the increase in energy expenditure is the result of muscle work, less -.
More than the basal metabolism is spent on muscle work. This expense is greater, the more intense the physical labor.
Energy consumption per person per day at low physical labor equal to 9211-11732 kJ, for moderate physical labor 11723-15073 kJ, for heavy physical labor 150773-18841-30146 kJ. Energy consumption among physical education students is on average 16,748 kJ.
Average energy consumption in kJ per 1 kg of body weight during (on - 3.9, lying awake - 4.63, reading aloud - 6.3, typing - 8.4, homework- 7.55-12.6, calm running on a flat road - 25.2, speed running 100 m - 189, skiing at a speed of 12 km per hour - 50.5, rowing - 10.5-25, 2, cycling - 14.7-37.8.
In humans, energy expenditure during mental work is 2-3% higher than the basal metabolic rate, and if mental work is accompanied by muscular activity during emotions (lecturer, speaker, artist, etc.), then energy expenditure increases by 10-20% for several days.