Basic and general metabolism. What is metabolism in simple terms: definition and description. A positive calorie balance is essential to build muscle

The concept of metabolism. Main and general exchange

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Article subject:	The concept of metabolism. Main and general exchange
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Metabolism and energy- is a combination of physical, chemical and physiological processes of absorption of nutrients in the body with the release of energy. In metabolism (metabolism), two interrelated, but multidirectional processes are distinguished - anabolism and catabolism. Anabolism is a set of processes of biosynthesis of organic compounds, components of cells, organs and tissues from absorbed nutrients. catabolism- these are the processes of splitting 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 dietary proteins, fats and carbohydrates.

Main exchange it is customary to call the amount of energy, ĸᴏᴛᴏᴩᴏᴇ spends the body at complete muscle rest, 12-14 hours after eating and at an ambient temperature of 20-22 ° C. The basic metabolism maintains the life of the organism 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 in cells and tissues, the metabolism - the basis of the life of the organism - does not stop. An indicator of the main 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, which maintains the relative constancy of the composition of proteins, the chemical composition of blood, temperature, etc., relatively independent of changes in the external environment, under different living conditions. The activity of the endocrine glands also significantly affects the basal metabolism. For example, the basal metabolism increases with an increase in the function of the thyroid gland and, on the contrary, decreases with a decrease in its functions and the pituitary gland. With an increase in body temperature by 1 ° C, the basal metabolism increases by an average of 10%. In a cold climate, the basal metabolism increases, and in a hot climate it decreases by 10-20%. During sleep, as a result of relaxation of skeletal muscles, it decreases to 13%. During starvation, the basal metabolic rate decreases. From 20 to 40 years, the basal metabolic rate is maintained at approximately the same level, and then gradually drops: in men to 7%, and in women to 17%.

A large 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 action of proteins is especially great. On average, after eating protein foods, basal metabolism increases by 30-37%, and after fats and carbohydrates by 4-6%.

The concept of metabolism. Basic and general exchange - concept and types. Classification and features of the category "The concept of metabolism. Basic and general metabolism" 2017, 2018.

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Under main exchange(OO) understand the minimum level energy consumption, necessary to maintain the vital activity of the organism in conditions of relatively complete physical and emotional rest.

In a state of relative rest, energy is spent on the implementation of the functions of the nervous system, the constantly ongoing synthesis of substances, the operation of ion pumps, the maintenance of body temperature, the work of the respiratory muscles of smooth muscles, the work of the heart and kidneys.

Energy consumption of the body increases during physical and mental work, psycho-emotional stress, after eating, with a decrease in temperature.

Definition of basal metabolism

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In order to exclude the influence of the listed factors on the amount of energy consumption, the determination of RO is carried out under standard strictly controlled conditions:

1. In the morning, in the supine position, with maximum muscle relaxation,

2. In the state of wakefulness, in conditions of thermal comfort (about 22 ° C),

3. On an empty stomach (12-14 hours after eating).

The RO values obtained under such conditions characterize the initial "basal" the level of energy consumption of the body.

For an adult, the average RO value is 1 kcal/kg/hour. From here

for a man weighing 70 kg, the amount of energy consumption of OO is about 1700 kcal / day,
for women - about 1500 kcal / day.

body surface law

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Energy costs per 1 kg of body weight can vary widely. The intensity of basal metabolism is more closely related to the size of the body surface, which is due to the direct dependence of the amount of heat transfer on the surface area of the body. Even in the last century, the German physiologist M. Rubner showed that in warm-blooded organisms with different body sizes, the same amount of heat is dissipated from 1 m 2 of the body surface into the environment.

On this basis, Rubner formulated body surface law , Whereby The energy costs of a warm-blooded organism are proportional to the size of the body surface.

Calculation of the main exchange

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The values of the Basic Metabolism are determined, and also calculated according to the equations, taking into account gender, age, height and body weight (Table 10.4).

Floor	Age (years)	Equations for calculating RO (kcal / day)
M	10 — 18	16.6 mt + 119R + 572
AND		7.4 mt + 482R + 217
M	18 — 30	15.4 mt - 27Р + 717
AND		13.3 mt + 334R + 35
M	30 — 60	11.3 mt + 16R + 901
AND		8.7 mt - 25R + 865
M	> 60	8.8 mt + 1128R - 1071
AND		9.2 mt + 637R - 302
mt - body weight (kg), P - height (m)

The value of RO depends on the ratio of the processes of anabolism and catabolism in the body.

The predominance of anabolic-oriented processes in metabolism in childhood over catabolic-oriented processes causes higher values of RO values in children (1.8 kcal/kg/h and 1.3 kcal/kg/h in children 7 and 12 years old, respectively) compared to with adults (1 kcal / kg / h), in which the processes of anabolism and catabolism are balanced in the state of health.

For each age group of people, the values \u200b\u200bof the Basal Metabolism are established and accepted as standards. This makes it possible, if necessary, to measure the value of RO in a person and compare the indicators obtained from him with the normative ones. The deviation of the RO value from the standard by no more than ± 10% is considered within the normal range. Sharper deviations of RO can serve as diagnostic signs of such conditions of the body as impaired thyroid function; recovery after severe and prolonged illness, accompanied by activation of metabolic processes: intoxication and shock, accompanied by inhibition of metabolism.

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Energy costs of the body in conditions of physical activity. The intensity of metabolic processes in the body increases significantly under conditions physical activity. The direct dependence of the amount of energy consumption on the severity of the load makes it possible to use the level of energy consumption as one of the indicators of the intensity of the work performed (Table 10.5).

As another criterion for determining the intensity of physical work performed by the body, the rate of oxygen consumption can be taken. However, this indicator during heavy physical exertion does not reflect the exact energy consumption, since the body receives part of the energy from anaerobic glycolysis processes that do not consume oxygen.

Working increase

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The difference between the values of the energy consumption of the body for the performance of various types of work and the energy consumption for the main metabolism is the so-calledworking increase .

The maximum permissible severity of work performed over a number of years should not exceed the level of basal metabolism for a given individual by more than three times in terms of energy consumption.

Mental labor does not require as much energy as physical labor. The energy consumption of the body increases during mental work by an average of only 2-3%. Mental work, accompanied by light muscular activity, psycho-emotional stress, leads to an increase in energy costs by 11-19% or more.

Specific dynamic action of food

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Specific dynamic action of food- an increase in the intensity of metabolism under the influence of food intake and an increase in the energy costs of the body relative to the levels of metabolism and energy costs that occurred before the meal.

The specific-dynamic effect of food is due to the expenditure of energy on:

1. Digestion of food,

2. Absorption of nutrients from the gastrointestinal tract into the blood and lymph,

3. Resynthesis of protein, complex lipid and other molecules;

4. Influence on the metabolism of biologically active substances entering the body as part of food (especially protein) and formed in it during digestion (see also Chapter 9).

An increase in the energy consumption of the body above the level that took place before eating, manifests itself approximately one hour after eating, reaches a maximum after three hours, which is due to the development by this time of a high intensity of the processes of digestion, absorption and resynthesis of substances entering the body. The specific dynamic action of food can last 12-18 hours. It is most pronounced when taking protein food, which increases the metabolic rate up to 30%, and less significant when taking mixed food, which increases the metabolic rate by 6-15%.

The level of total energy expenditure, like the Basic Metabolism, depends on age:

Daily energy consumption increases in children from 800 kcal (6 months -1 year) to 2850 kcal (11-14 years).

A sharp increase in energy consumption takes place in adolescent boys aged 14-17 years (3150 kcal).

After 40 years, energy consumption decreases and by the age of 80 is about 2000-2200 kcal / day.

In everyday life, the level of energy consumption in an adult depends not only on the characteristics of the work performed, but also on the general level of physical activity, the nature of rest and social living conditions.

Metabolism and energy is a combination of physical, chemical and physiological processes of absorption of nutrients in the body with the release of energy. In metabolism (metabolism), two interrelated, but differently directed processes are distinguished - 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 splitting 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 dietary proteins, fats and carbohydrates.

Main exchange called the amount of energy that the body spends at complete muscle rest, 12-14 hours after eating and at an ambient temperature of 20-22 ° C. The main 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 in cells and tissues, the metabolism - the basis of the life of the organism - does not stop. An indicator of the main 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, which maintains the relative constancy of the composition of proteins, the chemical composition of blood, temperature, etc., relatively independent 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 with an increase in thyroid function and, conversely, decreases with a decrease in thyroid and pituitary functions. With an increase in body temperature on GS, the basal metabolism increases by an average of 10%. In a cold climate, the basal metabolism increases, and in a hot climate it decreases by 10-20%. During sleep, as a result of relaxation of skeletal muscles, it decreases to 13%. During starvation, the basal metabolic rate decreases. From 20 to 40 years, the basal metabolic rate is maintained at approximately the same level, and then gradually drops: in men to 7%, and in women to 17%.

General metabolism- Occurs under normal conditions. It is much higher than the basic 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 this case in excess of the basic 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 is 2200-2800 kcal (9240-11760 kJ), mechanized labor - 2800-3600 kcal (11760-15120 kJ), heavy physical labor - 3600-4500 kcal (15120-18900 kJ), and with 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 run for 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.

With mental work, the overall metabolism increases slightly - by 2-3%, and if mental work is accompanied by muscular 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 action of proteins is especially great. On average, after eating protein foods, basal metabolism increases by 30% - 37%, and after eating fats and carbohydrates, on average, by 4% - 6%.

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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 are contained in this product. So, for example, the energy value of nuts turns out to be 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 vegetable origin.

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

All these definitions can be made much easier by studying gas exchange. Determination of the amount of energy released by the body, using the study of 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 have been decomposed over a certain period of time, you can calculate the amount of released energy.

Distinguish between general metabolism and basal metabolism. Main exchange called the energy costs of the body at rest, associated with maintaining the minimum level of metabolic processes necessary for the vital activity 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 the work of the heart, 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 4200 to 8400 kJ per day for men and from 4200 to 7140 kJ for women. On average, in a middle-aged person, the basal metabolism is 4187 J per 1 kg of mass per hour, or 7140 - 7560 thousand J per day. In children 8 - 9 years old, the basal metabolism is 2 - 2.5 times greater than in an adult.

The smaller the child, the more energy is spent on its growth. So, 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 greater the change in resting metabolism.

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

The second after the main metabolism component of the body's energy expenditure are the so-called adjustable energy costs. They correspond to the need for energy used for work in excess of the basic exchange. Any kind of muscular activity, even a change in body position (from a lying position to a sitting position), increases the energy consumption of the body. The change in the value of energy consumption is determined by the duration, intensity and nature of muscle work. The increase in metabolism is the more significant, the more intense the muscle load was. In this regard, workers of various professions spend unequal 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, the 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.

Chapter 14

THERMOREGULATION PROCESS

Energy exchange in the body

thermoregulation

General characteristics of energy exchange. BX

Energy is needed for the life of an organism. It exists in it in four main forms: chemical, mechanical, electrical and thermal. The central place among these forms belongs to chemical energy (ATP), which can be irreversibly converted into all other types of energy. In this way, energy exchange- this is a set of processes for the conversion of various forms of energy among themselves, as well as the accumulation and use of high-energy compounds. Macroergic (high-energy) compounds called biologically active organic compounds that have a fragile chemical bond, the splitting of which releases a sufficient amount of free energy to perform useful work in the cell: the synthesis of chemical compounds, the transport of substances against their concentration gradient, muscle contraction, etc.

Energy is spent on the processes of cell synthesis, on the implementation of various physiological functions, on external work, maintaining body temperature, etc. The continuation of life is possible only with the constant replenishment of energy reserves, which happens due to food intake. When 1 g of fat is oxidized in the body, 9.3 kcal is released, 1 g of protein and carbohydrates - 4.1 kcal each, respectively.

Kilocalorie (kcal) - the amount of heat (energy) required to raise the temperature of 1 kg of water by 1°C. The largest part of the energy released in the body goes into heat and only one fifth (20%) goes into mechanical energy. A small part of the released energy is converted into electrical energy. Ultimately, all types of energy are released into the environment mainly in the form of thermal energy.

The ratio of the amount of energy supplied with food and the energy expended by the body is called the energy balance. It can be positive, balanced and negative. With excess nutrition that exceeds the actual energy expenditure, the energy balance is positive, there is an accumulation of energy reserves due to an increase in the mass of adipose tissue. In conditions of malnutrition, the energy balance is negative, the reserves of energy-rich substances decrease. To have an idea of the amount of energy consumed by the body, it is enough to measure the amount of heat that is released into the external environment.

The exchange of human energy, or the so-called general exchange, consists of the basic exchange and the working increase. Basal metabolism is the minimum level of metabolism and energy expenditure of an awake person in a state of muscular and mental rest, on an empty stomach and at an ambient temperature of 18-20 ° C. A working increase is an increase in the body's energy costs during muscular work. For men of middle age (approximately 35 years), average height (approximately 170 cm) and with an average body weight (approximately 70 kg), the basal metabolism is 1 kcal per 1 kg of body weight per hour, or 1700 kcal per day. In women of the same weight, it is approximately 5-10% lower. It is higher in children than in adults. In old age, the basal metabolic rate decreases. Under conditions of basal metabolism, energy is spent on maintaining the vital activity of the body, the work of internal organs, and maintaining body temperature.

With febrile diseases (malaria, typhoid fever, tuberculosis, etc.), hyperfunction of the thyroid gland, the basic metabolism can increase up to 150%. With hypofunction of the pituitary gland, thyroid gland, gonads, the basal metabolism decreases, and fat deposition increases.

After eating, the intensity of metabolism and energy costs of the body increase compared to their level under conditions of basal metabolism. This effect of food intake on metabolism and energy consumption is called the specific dynamic action of food. With protein food, the metabolism increases by an average of 30%, with eating fats and carbohydrates - by 15%.