1. What process ensures the release of energy in the body? What is its essence?

Dissimilation (catabolism), i.e., the breakdown of cellular structures and compounds of the body with the release of energy and decay products.

2. What nutrients provide energy in the body?

Carbohydrates, fats and proteins.

3. Name the main methods for determining the amount of energy in a sample of a product.

Physical calorimetry; physicochemical methods for determining the amount of nutrients in a sample with subsequent calculation of the energy contained in it; according to tables.

4. Describe the essence of the method of physical calorimetry.

A sample of the product is burned in the calorimeter, and then the released energy is calculated based on the degree of heating of the water and the calorimeter material.

5. Write a formula for calculating the amount of heat released during combustion of a product in a calorimeter. Decipher its symbols.

Q = MvSv (t 2 - t 1) + MkSk (t 2 - t 1) - Qо,

where Q is the amount of heat, M is the mass (w - water, k - calorimeter), (t 2 - t 1) is the temperature difference between water and calorimeter after and before combustion of the sample, C is the specific heat capacity, Qo is the amount of heat generated by the oxidizer .

6. What are the physical and physiological caloric coefficients of a nutrient?

The amount of heat released during the combustion of 1 g of a substance in a calorimeter and in the body, respectively.

7. How much heat is released when 1 g of proteins, fats and carbohydrates are burned in a calorimeter?

1g protein – 5.85 kcal (24.6 kJ), 1g fat – 9.3 kcal (38.9 kJ), 1g carbohydrates – 4.1 kcal (17.2 kJ).

8. Formulate Hess’s law of thermodynamics, on the basis of which the energy entering the body is calculated based on the amount of digested proteins, fats and carbohydrates.

The thermodynamic effect depends only on the heat content of the initial and final reaction products and does not depend on the intermediate transformations of these substances.

9. How much heat is released during the oxidation of 1 g of proteins, 1 g of fats and 1 g of carbohydrates in the body?

1 g of proteins – 4.1 kcal (17.2 kJ), 1 g of fats – 9.3 kcal (38.9 kJ), 1 g of carbohydrates – 4.1 kcal (17.2 kJ).

10. Explain the reason for the difference between the physical and physiological caloric coefficients for proteins. In what case is it greater?

In the calorimeter (physical coefficient), the protein decomposes to the final products - CO 2, H 2 O and NH 3 with the release of all the energy contained in them. In the body (physiological coefficient), proteins break down into CO 2, H 2 O, urea and other substances of protein metabolism, which contain energy and are excreted in the urine.

The content of proteins, fats and carbohydrates in food products is determined, their amount is multiplied by the corresponding physiological caloric coefficients, summed up and 10% is subtracted from the sum, which is not absorbed in the digestive tract (losses in feces).

12. Calculate (in kcal and kJ) the energy intake when 10 g of proteins, fats and carbohydrates are taken into the body with food.

Q = 4.110 + 9.310 + 4.110 = 175 kcal. (175 kcal - 17.5 kcal) x 4.2 kJ, where 17.5 kcal is the energy of undigested nutrients (losses in feces - about 10%). Total: 157.5 kcal (661.5 kJ).

Calorimetry: direct (Atwater-Benedict method); indirect, or indirect (methods of Krogh, Shaternikov, Douglas - Holden).

14. What is the principle of direct calorimetry based on?

On direct measurement of the amount of heat generated by the body.

15. Briefly describe the design and operating principle of the Atwater-Benedict camera.

The chamber in which the test subject is placed is thermally isolated from the environment; its walls do not absorb heat; inside they are radiators through which water flows. Based on the degree of heating of a certain mass of water, the amount of heat consumed by the body is calculated.

16. What is the principle of indirect (indirect) calorimetry based on?

By calculating the amount of energy released according to gas exchange data (absorbed O 2 and released CO 2 per day).

17. Why can the amount of energy released by the body be calculated based on gas exchange rates?

Because the amount of O 2 consumed by the body and CO 2 released corresponds exactly to the amount of oxidized proteins, fats and carbohydrates, and therefore the energy consumed by the body.

18. What coefficients are used to calculate energy consumption by indirect calorimetry?

Respiratory coefficient and caloric equivalent of oxygen.

19. What is called the respiratory coefficient?

The ratio of the volume of carbon dioxide released by the body to the volume of oxygen consumed during the same time.

20. Calculate the respiratory coefficient (RC) if it is known that the inhaled air contains 17% oxygen and 4% carbon dioxide.

Since atmospheric air contains 21% O 2, the percentage of absorbed oxygen is 21% - 17%, i.e. 4%. CO 2 in exhaled air is also 4%. From here

21. What does the respiratory coefficient depend on?

22. What is the respiratory coefficient during the oxidation in the body to the final products of proteins, fats and carbohydrates?

During the oxidation of proteins – 0.8, fats – 0.7, carbohydrates – 1.0.

23. Why is the respiratory quotient lower for fats and proteins than for carbohydrates?

More O 2 is consumed for the oxidation of proteins and fats, since they contain less intramolecular oxygen than carbohydrates.

24. What value does a person’s respiratory quotient approach at the beginning of intense physical work? Why?

To one, because the source of energy in this case is mainly carbohydrates.

25. Why is a person’s respiratory coefficient greater than one in the first minutes after intense and prolonged physical work?

Because more CO 2 is released than O 2 is consumed, since lactic acid accumulated in the muscles enters the blood and displaces CO 2 from bicarbonates.

26. What is called the caloric equivalent of oxygen?

The amount of heat released by the body when consuming 1 liter of O 2.

27. What does the caloric equivalent of oxygen depend on?

From the ratio of proteins, fats and carbohydrates oxidized in the body.

28. What is the caloric equivalent of oxygen during the oxidation in the body (in the process of dissimilation) of proteins, fats and carbohydrates?

For proteins - 4.48 kcal (18.8 kJ), for fats - 4.69 kcal (19.6 kJ), for carbohydrates - 5.05 kcal (21.1 kJ).

29. Briefly describe the process of determining energy consumption using the Douglas-Holden method (full gas analysis).

Within a few minutes, the subject inhales atmospheric air, and the exhaled air is collected in a special bag, its quantity is measured and gas analysis is carried out to determine the volume of oxygen consumed and CO 2 released. The respiratory coefficient is calculated, with the help of which the corresponding caloric equivalent of O 2 is found from the table, which is then multiplied by the volume of O 2 consumed over a given period of time.

30. Briefly describe M. N. Shaternikov’s method for determining energy expenditure in animals in an experiment.

The animal is placed in a chamber into which oxygen is supplied as it is consumed. CO 2 released during respiration is absorbed by alkali. The energy released is calculated based on the amount of O2 consumed and the average caloric equivalent of O2: 4.9 kcal (20.6 kJ).

31. Calculate energy consumption in 1 minute if it is known that the subject consumed 300 ml of O 2. The respiratory coefficient is 1.0.

DK = 1.0, it corresponds to the caloric equivalent of oxygen equal to 5.05 kcal (21.12 kJ). Therefore, energy consumption per minute = 5.05 kcal x 0.3 = 1.5 kcal (6.3 kJ).

32. Briefly describe the process of determining energy consumption using the Krogh method in humans (incomplete gas analysis).

The subject inhales oxygen from the metabolimeter bag, the exhaled air returns to the same bag, having previously passed through a CO 2 absorber. Based on the readings of the metabolimeter, the O2 consumption is determined and multiplied by the caloric equivalent of oxygen 4.86 kcal (20.36 kJ).

33. Name the main differences in calculating energy consumption using the Douglas-Holden and Krogh methods.

The Douglas–Holden method involves calculating energy consumption based on data from a complete gas analysis; Krogh's method - only by the volume of oxygen consumed using the caloric equivalent of oxygen characteristic of basal metabolic conditions.

34. What is called the basal metabolism?

Minimum energy consumption that ensures homeostasis under standard conditions: while awake, with maximum muscular and emotional rest, on an empty stomach (12 - 16 hours without food), at a comfortable temperature (18 - 20C).

35. Why is basal metabolism determined under standard conditions: maximum muscular and emotional rest, on an empty stomach, at a comfortable temperature?

Because physical activity, emotional stress, food intake and changes in ambient temperature increase the intensity of metabolic processes in the body (energy consumption).

36. What processes consume basal metabolic energy in the body?

To ensure the vital functions of all organs and tissues of the body, cellular synthesis, and to maintain body temperature.

37. What factors determine the value of the proper (average) basal metabolic rate of a healthy person?

Gender, age, height and body mass (weight).

38. What factors, besides gender, weight, height and age, determine the value of the true (real) basal metabolic rate of a healthy person?

Living conditions to which the body is adapted: permanent residence in a cold climate zone increases basal metabolism; long-term vegetarian diet – reduces.

39. List the ways to determine the amount of proper basal metabolism in a person. What method is used to determine the value of a person’s true basal metabolic rate in practical medicine?

According to tables, according to formulas, according to nomograms. Krogh method (incomplete gas analysis).

40. What is the value of basal metabolism in men and women per day, as well as per 1 kg of body weight per day?

For men, 1500 – 1700 kcal (6300 – 7140 kJ), or 21 – 24 kcal (88 – 101 kJ)/kg/day. Women have approximately 10% less than this value.

41. Is the basal metabolic rate calculated per 1 m 2 of body surface and per 1 kg of body weight the same in warm-blooded animals and humans?

When calculated per 1 m 2 of body surface in warm-blooded animals of different species and humans, the indicators are approximately equal, when calculated per 1 kg of mass they are very different.

42. What is called a working exchange?

The combination of basal metabolism and additional energy expenditure that ensures the functioning of the body in various conditions.

43. List the factors that increase energy consumption by the body. What is called the specific dynamic effect of food?

Physical and mental stress, emotional stress, changes in temperature and other environmental conditions, specific dynamic effects of food (increased energy consumption after eating).

44. By what percentage does the body’s energy consumption increase after eating protein and mixed foods, fats and carbohydrates?

After eating protein foods - by 20 - 30%, mixed foods - by 10 - 12%.

45. How does ambient temperature affect the body’s energy expenditure?

Temperature changes in the range of 15 – 30C do not significantly affect the body’s energy consumption. At temperatures below 15C and above 30C, energy consumption increases.

46. ​​How does metabolism change at ambient temperatures below 15? What does it matter?

Increasing. This prevents the body from cooling down.

47. What is called the body’s efficiency during muscular work?

Expressed as a percentage, the ratio of the energy equivalent to useful mechanical work to the total energy expended in performing that work.

48. Give a formula for calculating the coefficient of performance (efficiency) in a person during muscular work, indicate its average value, decipher the elements of the formula.

where A is energy equivalent to useful work, C is total energy consumption, e is energy consumption for the same period of time at rest. The efficiency is 20%.

Poikilothermic animals (cold-blooded) - with an unstable body temperature, depending on the ambient temperature; homeothermic (warm-blooded) - animals with a constant body temperature that does not depend on the ambient temperature.

50. What is the importance of constancy of body temperature for the body? In which organs does the process of heat formation occur most intensively?

Provides a high level of vital activity relatively regardless of ambient temperature. In muscles, lungs, liver, kidneys.

51. Name the types of thermoregulation. Formulate the essence of each of them.

Chemical thermoregulation - regulation of body temperature by changing the intensity of heat production; physical thermoregulation - by changing the intensity of heat transfer.

52. What processes provide heat transfer?

Heat radiation (radiation), heat evaporation, heat conduction, convection.

53. How does the lumen of skin blood vessels change when the ambient temperature decreases and increases? What is the biological significance of this phenomenon?

When the temperature drops, the blood vessels in the skin narrow. As the ambient temperature rises, the blood vessels in the skin dilate. The fact is that changing the width of the lumen of blood vessels, regulating heat transfer, helps maintain a constant body temperature.

54. How and why does heat production and heat transfer change with strong stimulation of the sympathoadrenal system?

Heat production will increase due to stimulation of oxidative processes, and heat transfer will decrease as a result of narrowing of skin vessels.

55. List the areas of localization of thermoreceptors.

Skin, cutaneous and subcutaneous vessels, internal organs, central nervous system.

56. In what parts and structures of the central nervous system are thermoreceptors located?

In the hypothalamus, reticular formation of the midbrain, in the spinal cord.

57. In which parts of the central nervous system are thermoregulation centers located? Which structure of the central nervous system is the highest center of thermoregulation?

In the hypothalamus and spinal cord. Hypothalamus.

58. What changes will occur in the body with a long-term absence of fats and carbohydrates in the diet, but with an optimal intake of protein from food (80 - 100 g per day)? Why?

There will be an excess of nitrogen consumption by the body over intake, and weight loss, since energy costs will be covered mainly by proteins and fat reserves that are not replenished.

59. In what quantity and in what ratio should proteins, fats and carbohydrates be contained in the diet of an adult (average version)?

Proteins – 90 g, fats – 110 g, carbohydrates – 410 g. Ratio 1: 1, 2: 4, 6.

60. How does the state of the body change with excess fat intake?

Obesity and atherosclerosis develop (prematurely). Obesity is a risk factor for the development of cardiovascular diseases and their complications (myocardial infarction, stroke, etc.), and reduced life expectancy.

1. What is the ratio of basal metabolic values ​​in children of the first 3–4 years of life, during puberty, at the age of 18–20 years and adults (kcal/kg/day)?

Up to 3–4 years of age, children have approximately 2 times more, during puberty – 1.5 times more than adults. At 18–20 years old it corresponds to the adult norm.

2. Draw a graph of changes in basal metabolic rate in boys with age (in girls, basal metabolic rate is 5% lower).

3. What explains the high intensity of oxidative processes in a child?

A higher level of metabolism of young tissues, a relatively large surface area of ​​the body and, naturally, greater energy expenditure to maintain a constant body temperature, increased secretion of thyroid hormones and norepinephrine.

4. How do energy costs for growth change depending on the age of the child: up to 3 months of life, before the onset of puberty, during puberty?

They increase in the first 3 months after birth, then gradually decrease, and increase again during puberty.

5. What does the total energy expenditure of a 1-year-old child consist of and how is it distributed as a percentage compared to an adult?

In a child: 70% falls on the basal metabolism, 20% on movement and maintaining muscle tone, 10% on the specific dynamic effect of food. In an adult: 50 – 40 – 10%, respectively.

6. Do adults or children 3–5 years of age expend more energy when performing muscular work to achieve the same beneficial result, by how many times and why?

Children, 3 to 5 times, since they have less perfect coordination, which leads to excessive movements, resulting in significantly less useful work for children.

7. How does energy expenditure change when a child cries, by what percentage, and as a result of what?

Increases by 100–200% due to increased heat production as a result of emotional arousal and increased muscle activity.

8. What part (in percentage) of an infant’s energy expenditure is provided by proteins, fats, and carbohydrates? (compare with the adult norm).

Due to proteins - 10%, due to fats - 50%, due to carbohydrates - 40%. In adults – 20 – 30 – 50%, respectively.

9. Why do children, especially in infancy, quickly overheat when the ambient temperature rises? Do children tolerate increases or decreases in ambient temperature more easily?

Because children have increased heat production, insufficient sweating and, therefore, heat evaporation, an immature thermoregulation center. Demotion.

10. Name the immediate cause and explain the mechanism of rapid cooling of children (especially infants) when the ambient temperature drops.

Increased heat transfer in children due to a relatively large body surface, abundant blood supply to the skin, insufficient thermal insulation (thin skin, lack of subcutaneous fat) and immaturity of the thermoregulation center; insufficient vasoconstriction.

11. At what age does a child begin to experience daily temperature fluctuations, how do they differ from those in adults, and at what age do they reach adult norms?

At the end of 1 month of life; they are insignificant and reach the adult norm by five years.

12. What is a child’s temperature “comfort zone”, what temperature is it within, what is this indicator for adults?

The external temperature at which individual fluctuations in the temperature of a child’s skin are least pronounced is in the range of 21 – 22 o C, in an adult – 18 – 20 o C.

13. Which thermoregulation mechanisms are most ready to function at the time of birth? Under what conditions can the mechanisms of trembling thermogenesis be activated in newborns?

Increased heat generation, predominantly of non-shivering origin (high metabolism), sweating. Under conditions of extreme cold exposure.

14. In what ratio should proteins, fats and carbohydrates be contained in the diet of children aged three and six months, 1 year, over one year and adults?

Up to 3 months – 1: 3: 6; at 6 months – 1: 2: 4. At the age of 1 year and older – 1: 1, 2: 4, 6, i.e., the same as in adults.

15. Name the features of the metabolism of mineral salts in children. What is this connected with?

There is retention of salts in the body, especially increased need for calcium, phosphorus and iron, which is associated with the growth of the body.

11 Energy exchange

An indispensable condition for maintaining life is that organisms receive energy from the external environment, and although the primary source of energy for all living things is the Sun, only plants are capable of directly using its radiation. Through photosynthesis, they convert the energy of sunlight into the energy of chemical bonds. Animals and humans get the energy they need by eating plant foods. (For carnivores and partly for omnivores, other animals - herbivores - serve as a source of energy.)

Animals can also directly receive energy from sunlight; for example, poikilothermic animals maintain their body temperature in this way. However, heat (received from the external environment and generated in the body itself) cannot be converted into any other type of energy. Living organisms, unlike technical devices, are fundamentally incapable of this. A machine that uses the energy of chemical bonds (for example, an internal combustion engine) first converts it into heat and only then into work: the chemical energy of the fuel → warm → work (expansion of gas in the cylinder and movement of the piston). In living organisms, only this scheme is possible: chemical energy → Job.

So, the energy of chemical bonds in the molecules of food substances is practically the only source of energy for an animal organism, and thermal energy can only be used by it to maintain its body temperature. In addition, heat, due to rapid dissipation in the environment, cannot be stored in the body for a long period. If excess heat occurs in the body, then for homeothermic animals this becomes a serious problem and sometimes even threatens their life (see Section 11.3).

11.1. Sources of energy and ways of its transformation in the body

A living organism is an open energy system: it receives energy from the environment (almost exclusively in the form of chemical bonds), converts it into heat or work, and in this form returns it to the environment.

Components of nutrients that enter the blood from the gastrointestinal tract (for example, glucose, fatty acids or amino acids) are not themselves capable of directly transferring the energy of their chemical bonds to its consumers, for example, the potassium-sodium pump or muscle actin and myosin. There is a universal intermediary between food “energy carriers” and “consumers” of energy - adenosine triphosphate (ATP). He is the one direct source energy for any processes in living things

body. The ATP molecule is a combination of adenine, ribose and three phosphate groups (Fig. 11.1).

The bonds between acid residues (phosphates) contain a significant amount of energy. By splitting off the terminal phosphate under the action of the enzyme ATPase, ATP is converted into adenosine diphosphate (ADP). This releases 7.3 kcal/mol of energy. The energy of chemical bonds in food molecules is used for the resynthesis of ATP from ADP. Let's consider this process using glucose as an example (Fig. 11.2).

The first stage of glucose utilization is glycolysis During this process, a glucose molecule is first converted into pyruvic acid (pyruvat), while providing energy for ATP resynthesis. Pyruvate is then converted to acetyl coenzyme A - initial product for the next stage of recycling - Krebs cycle. The multiple transformations of substances that make up the essence of this cycle provide additional energy for the resynthesis of ATP and end with the release of hydrogen ions. The third stage begins with the transfer of these ions into the respiratory chain - oxidative phosphorylation, as a result of which ATP is also formed.

Taken together, all three stages of recycling (glycolysis, Krebs cycle and oxidative phosphorylation) constitute the process tissue respiration. It is fundamentally important that the first stage (glycolysis) takes place without the use of oxygen (anaerobic respiration) and leads to the formation of only two ATP molecules. The two subsequent stages (Krebs cycle and oxidative phosphorylation) can only occur in an oxygen environment (aerobic respiration). Complete utilization of one glucose molecule results in the appearance of 38 ATP molecules.

There are organisms that not only do not require oxygen, but also die in an oxygen (or air) environment - obligate anaerobes. These, for example, include bacteria that cause gas gangrene (Clostridium perfringes), tetanus (C. tetani), botulism (C. botulinum), etc.

In animals, anaerobic processes are an auxiliary type of respiration. For example, with intense and frequent muscle contractions (or with static contractions), the delivery of oxygen by the blood lags behind the needs of the muscle cells. At this time, ATP formation occurs anaerobically with the accumulation of pyruvate, which is converted into lactic acid (lactate). Growing oxygen debt. The cessation or weakening of muscle work eliminates the discrepancy between the tissue's need for oxygen and the possibilities of its delivery; lactate is converted into pyruvate, the latter either through the stage of acetyl coenzyme A is oxidized in the Krebs cycle to carbon dioxide, or through gluconeogenesis it turns into glucose.

According to the second law of thermodynamics, any transformation of energy from one type to another occurs with the obligatory formation of a significant amount of heat, which is then dissipated in the surrounding space. Therefore, the synthesis of ATP and the transfer of energy from ATP to the actual “energy consumers” occur with the loss of approximately half of it in the form of heat. Simplifying, we can represent these processes as follows (Fig. 11.3).

Approximately half of the chemical energy contained in food is immediately converted into heat and dissipated in space, the other half goes to the formation of ATP. With the subsequent breakdown of ATP, half of the released energy is again converted into heat. As a result, an animal and a person can spend no more than 1/4 of all energy consumed in the form of food to perform external work (for example, running or moving any objects in space). Thus, the efficiency of higher animals and humans (about 25%) is several times higher than, for example, the efficiency of a steam engine.

All internal work (except for the processes of growth and fat accumulation) quickly turns into heat. Examples: (a) the energy produced by the heart is converted into heat due to the resistance of blood vessels to the flow of blood; (b) the stomach does the work of secreting hydrochloric acid, the pancreas secretes bicarbonate ions, in the small intestine these substances interact, and the energy stored in them is converted into heat.

The results of external (useful) work performed by an animal or a person also ultimately turn into heat: the movement of bodies in space warms the air, erected structures collapse, giving up the energy embedded in them to the earth and air in the form of heat. The Egyptian pyramids are a rare example of how the energy of muscle contraction, expended almost 5,000 years ago, is still waiting for the inevitable transformation into heat.

Energy balance equation:

E = A + H + S,

Where E - the total amount of energy received by the body from food; A - external (useful) work; N - heat transfer; S- stored energy.

Energy losses through urine, sebum and other secretions are extremely small and can be neglected.

The respiratory coefficient is 18.10:24.70 = 0.73.[...]

The respiratory coefficient does not remain constant during normal fruit ripening. In the premenopausal stage it is approximately 1 and as it matures it reaches values ​​of 1.2... 1.5. With deviations of ±0.25 from one, metabolic abnormalities are not yet observed in the fruits, and only with large deviations can physiological disorders be assumed. The intensity of respiration of individual layers of tissue of any fetus is not the same. In accordance with the greater activity of enzymes in the skin, respiration rates are many times greater in it than in parenchymal tissue (Hulme and Rhodes, 1939). With a decrease in oxygen content and an increase in the concentration of carbon dioxide in parenchyma cells, the intensity of respiration decreases with distance from the skin to the core of the fruit.[...]

Instrument for determining the respiratory coefficient, tweezers, strips of filter paper, hourglass for 2 minutes, glass cups, pipettes, glass rods, 250 ml conical flasks.[...]

The device for determining the respiratory coefficient consists of a large test tube with a tightly fitting rubber stopper, into which a measuring tube bent at a right angle with a graph paper scale is inserted.[...]

Oxygen consumption and its utilization coefficient were constant when p02 was reduced to 60 and 20% of the original (depending on the flow rate). At oxygen concentrations slightly above the critical level, the maximum volume of ventilation was maintained for a long time (for several hours). The volume of ventilation increased by 5.5 times, but unlike carp, it decreased starting from 22% of the level of water saturation with oxygen. The authors believe that a decrease in the volume of ventilation in fish under extreme hypoxia is a consequence of oxygen deficiency of the respiratory muscles. The ratio of respiratory rate and heart rate was 1.4 normally and 4.2 with oxygen deficiency. [...]

Introductory explanations. Advantages of the method: high sensitivity, which allows you to work with small samples of experimental material; the ability to observe the dynamics of gas exchange and simultaneously take into account the gas exchange of 02 and C02, which allows you to establish the respiratory coefficient.[...]

Therefore, the pH value in the oxytank decreases to almost 6.0, while in the aeration tank pH>7D At maximum load, the power consumption for the oxytank, including the power of the equipment for producing oxygen 1.3 m3/ (hp-h) and power aerator (Fig. 26.9), should be less than the power of the aerator for the aeration tank. This is explained by the high concentration of oxygen (above 60%) in all stages of the oxygen tank.[...]

Dynamics of carbon dioxide release (С?СО2), oxygen absorption ([...]

Marine and freshwater fish under these experimental conditions had approximately the same respiratory coefficient (RQ). The disadvantage of these data is that the author took a goldfish for comparison, which generally consumes little oxygen and can hardly serve as a standard of comparison.[...]

With regard to the gas exchange of hibernating insects, it should be said that the respiratory coefficient also decreases1. For example, Dreyer (1932) found that in the active state of the ant Formica ulkei Emery the respiratory coefficient was 0.874; when the ants became inactive before hibernation, the respiratory coefficient decreased to 0.782, and during the hibernation period the decrease reached 0.509-0.504. The Colorado potato beetle Leptinotarsa ​​decemlineata Say. during the wintering period, the respiratory coefficient decreases to 0.492-0.596, while in the summer it is 0.819-0.822 (Ushatinskaya, 1957). This is explained by the fact that in the active state insects live mainly on protein and carbohydrate foods, while in hibernation they consume mainly fat, which requires less oxygen for oxidation. [...]

In sealed containers designed for pressure in the GP RK. d = 1962 Pa (200 mm water column), with high turnover rates, the duration of idle time for the tank with the “dead” residue before filling begins can be so short that the breathing valve does not have time to open for “exhalation”. Then there are no losses from “reverse exhalation”.[...]

To understand the biochemical processes occurring in the body, the value of the respiratory coefficient is of great importance. Respiratory coefficient (RC) is the ratio of exhaled carbonic acid to consumed oxygen.[...]

To judge the influence of temperature on any process, they usually operate on the value of the temperature coefficient. The temperature coefficient (t>ω) of the respiration process depends on the type of plant and on temperature gradations. Thus, with an increase in temperature from 5 to 15 ° C, 0 ω can increase to 3, while an increase in temperature from 30 to 40 ° C increases the respiration intensity less significantly (ω about 1.5). The phase of plant development is of great importance. According to B., A. Rubin, at each phase of plant development, the most favorable temperatures for the respiration process are those against the background of which this phase usually takes place. The change in optimal temperatures during plant respiration depending on the phase of their development is due to the fact that in the process of ontogenesis they change respiratory exchange pathways. Meanwhile, different temperatures are most favorable for different enzyme systems. In this regard, it is interesting that in later phases of plant development, cases are observed when flavin dehydrogenases act as final oxidases, transferring hydrogen directly to air oxygen.[...]

All studied fish in captivity consume less oxygen than in natural conditions. A slight increase in the respiratory coefficient in fish kept in aquariums indicates a change in the qualitative side of metabolism towards a greater participation of carbohydrates and proteins in it. The author explains this by the worse oxygen regime of the aquarium compared to natural conditions; In addition, the fish in the aquarium are inactive.[...]

To reduce the emission of harmful vapors, reflector disks are also used, installed under the mounting pipe of the breathing valve. With a high turnover rate of atmospheric tanks, the efficiency of reflector disks can reach 20-30%.[...]

Resaturation of the gas chamber can occur after filling if the gas space was not completely saturated with vapor. In this case, the breathing valve does not close after filling the container and additional exhalation immediately begins. This phenomenon occurs in tanks that have a high turnover ratio or are partially filled, not to the maximum filling height, as well as in tanks with slow saturation processes of the hydraulic fluid (tanks with pontoons and recessed ones). GP saturation is especially typical for tanks that are filled for the first time after cleaning and ventilation. This type of loss is sometimes called losses from saturation or oversaturation of the GP.[...]

For known u0 Acjcs can also be determined from graphs similar to those shown in Fig. 14. The methods for calculating losses provide similar graphs for typical RVS tanks, various types of breathing valves and their quantities. The value Ac/cs means the increase in concentration in the gas station during the total time of downtime (tp) and filling of the reservoir (te), i.e. t = t„ + t3; it is determined approximately from the graphs (see Fig. 3). When using formula (!9), it is necessary to keep in mind that with full saturation of the GP ccp/cs = 1 and that the time for complete saturation of the GP of ground-based reservoirs is limited to 2-4 days (depending on weather conditions and other conditions), and the graph is " Fig. 3 approximate. Therefore, having obtained the values ​​ccp/cs>l from formula (19), which means the onset of complete saturation of the gas supply before the end of the downtime or the end of filling the tank, it is necessary to substitute ccp/cs = 1.[ . ..]

Let us evaluate the quantitative relationships between these two gas flows. Firstly, the ratio of the volume of carbon dioxide released to the volume of oxygen consumed (respiratory coefficient) for most wastewater and activated sludge is less than one. Secondly, the volumetric mass transfer coefficients for oxygen and carbon dioxide are close to each other. Thirdly, the phase equilibrium constant of carbon dioxide is almost 30 times less than that of oxygen. Fourthly, carbon dioxide is not only present in the sludge mixture in a dissolved state, but also enters into a chemical interaction with water.[...]

When comparing both types of respiration, the unequal ratio of oxygen absorption to carbon dioxide release is striking. The CO2/O2 ratio is designated as the respiratory coefficient KO.[...]

If during respiration organic substances with a relatively higher oxygen content than in carbohydrates are oxidized, for example organic acids - oxalic, tartaric and their salts, then the respiratory coefficient will be significantly greater than 1. It will also be greater than 1 in the case when part of the oxygen, used for microbial respiration, taken from carbohydrates; or during the respiration of those yeasts in which alcoholic fermentation occurs simultaneously with aerobic respiration. If, along with aerobic respiration, other processes occur in which additional oxygen is used, then the respiratory coefficient will be less than 1. It will also be less than 1 when substances with a relatively low oxygen content, such as proteins, hydrocarbons, etc., are oxidized during the respiration process. Consequently, , knowing the value of the respiratory coefficient, you can determine which substances are oxidized during respiration.[...]

The most general indicator of the rate of oxidation is the rate of respiration, which can be judged by the absorption of oxygen, the release of carbon dioxide and the oxidation of organic matter. Other indicators of respiratory metabolism: the value of the respiratory coefficient, the ratio of the glycolytic and pentose phosphate pathways of sugar breakdown, the activity of redox enzymes. The energy efficiency of respiration can be judged by the intensity of oxidative phosphorylation of mitochondria.[...]

The trends shown for Cox Orange apples regarding the influence of oxygen and carbon dioxide concentrations in the chamber air are valid for all other apple varieties, except for cases where the respiratory coefficient increases more strongly with decreasing temperature. [...]

The value of DC depends on other reasons. In some tissues, due to the difficult access of oxygen, along with aerobic respiration, anaerobic respiration occurs, which is not accompanied by the absorption of oxygen, which leads to an increase in the DC value. The value of the coefficient is also determined by the completeness of oxidation of the respiratory substrate. If, in addition to the final products, less oxidized compounds (organic acids) accumulate in the tissues, then DC[...]

Quantitative determinations of the dependence of gas exchange in fish on temperature have been carried out by many researchers. In most cases, the study of this issue was limited primarily to the quantitative side of respiration - the magnitude of the respiratory rhythm, the amount of oxygen consumption and then the calculation of temperature coefficients at different temperatures.[...]

To reduce losses due to evaporation and air pollution, gasoline tanks are equipped with a gas piping connecting the air spaces of the tanks in which products of the same brand are stored, and a common breathing valve is installed. The “large and small breathing” described above, ventilation of the gas space, also cause air pollution during the storage of petroleum products at agricultural facilities, since with a tank farm turnover ratio of 4-6, the fuel inventory turnover ratio is 10-20, which means a decrease in the ratio use of tanks 0.4-0.6. In order to prevent air pollution, oil depots are equipped with cleaning devices and gasoline-oil traps.[...]

The data obtained to date show that extreme temperatures cause inhibition of the physiological system, in particular the transport of gases in fish. At the same time, bradycardia develops, arrhythmia increases, oxygen consumption and its utilization rate decrease. Following these changes in the functioning of the cardiorespiratory apparatus, ventilation of the gills gradually ceases and, last of all, the myocardium ceases to function. Apparently, anoxia of the respiratory muscles and general oxygen deficiency are one of the reasons for the death of fish due to overheating. An increase in temperature leads to an acceleration of oxygen utilization and, as a consequence, to a drop in its tension in the dorsal aorta, which, in turn, serves as a signal for increased ventilation of the gills.[...]

Before using the model, its kinetic parameters should be checked. Validation of a pure oxygen system model for the treatment of domestic and industrial wastewater has been done by Muller et al.(1). Model validation for domestic wastewater used a respiratory coefficient R.C of 1.0, while for industrial wastewater it is 0.85 and even 0.60. Additional verification of chemical interactions was made quite recently when studying wastewater from a pulp and paper mill (Fig. 26.6). To evaluate the data obtained, the respiratory coefficient was assumed to be 0.90. there was not so much nitrogen, and a lower requirement for it for the growth of microorganisms was noted than traditionally observed in biological systems. [...]

To solve the question of the essence of the effect of temperature on the metabolism of fish, it is necessary to know not only the degree of increase or decrease in metabolism with a change in temperature, but also qualitative changes in the individual links that make up the metabolism. The qualitative side of metabolism can to some extent be characterized by such coefficients as respiratory and ammonia (the ratio of released ammonia as the final product of nitrogen metabolism to consumed oxygen) (Fig. 89).[...]

From the above equation (4) it follows that the ratio of the constants for 02 and CO2 is equal to 1.15, i.e., the use of the CO2 balance measurement technique would seem to allow observations to be made at slightly higher values ​​of 2 and correspondingly higher flow velocities. But this apparent advantage disappears if we assume that the respiratory coefficient is less than 1. In addition, as Talling showed 32], the accuracy of determining CO2 in natural waters cannot be better than ± 1 µmol/l (0.044 mg/l), and oxygen - ±0.3 µmol/l (0.01 mg/l). Consequently, even if we take the respiratory coefficient equal to 1, the accuracy of the balance method, based on taking into account the balance of oxygen, turns out to be at least three times higher than when determining carbon dioxide. [...]

The morpho-physiological method was used in our studies with some additions. This made it possible to determine with sufficient accuracy (±3.5%) the amount of absorbed oxygen, released carbon dioxide and respiratory coefficient (RQ) on whole seedlings 10-12 days old and leaves of plants from field experiments. The principle of this technique is that plants placed in a closed vessel (specially designed gas pipette) with atmospheric air change the composition of the air as a result of respiration. Thus, knowing the volume of the vessel and determining the percentage composition of the air at the beginning and end of the experiment, it is not difficult to calculate the amount of CO2 absorbed and released by plants. [...]

Various plant organs and tissues vary greatly in the conditions for supplying them with oxygen. In a leaf, oxygen flows freely to almost every cell. Juicy fruits, roots, tubers are very poorly ventilated; they are poorly permeable to gases, not only to oxygen, but also to carbon dioxide. Naturally, in these organs the respiration process shifts to the anaerobic side, and the respiratory coefficient increases. An increase in the respiratory coefficient and a shift in the respiration process to the anaerobic side are observed in meristematic tissues. Thus, different organs are characterized not only by different intensity, but also by unequal quality of the respiratory process.[...]

The question of substances used in the process of respiration has long been an issue for physiologists. Even in the works of I.P. Borodin, it was shown that the intensity of the respiration process is directly proportional to the content of carbohydrates in plant tissues. This gave reason to assume that carbohydrates are the main substance consumed during respiration. In clarifying this issue, determining the respiratory coefficient is of great importance. The respiratory coefficient is the volumetric or molar ratio of CO2 released during respiration to the CO2 absorbed during the same period of time. With normal access to oxygen, the value of the respiratory coefficient depends on the substrate of respiration. If carbohydrates are used in the breathing process, then the process proceeds according to the equation CeH) 2O5 + 6O2 = 6CO2 + 6H2O, in this case the respiratory coefficient is equal to one! = 1. However, if more oxidized compounds, such as organic acids, undergo decomposition during respiration, oxygen absorption decreases, and the respiratory coefficient becomes greater than unity. When more reduced compounds, such as fats or proteins, are oxidized during respiration, more oxygen is required and the respiratory coefficient becomes less than unity.[...]

So, the simplest process of aerobic respiration is represented in the following form. Molecular oxygen consumed during respiration is used mainly to bind hydrogen generated during the oxidation of the substrate. Hydrogen from the substrate is transferred to oxygen through a series of intermediate reactions that occur sequentially with the participation of enzymes and carriers. The so-called respiratory coefficient gives a certain idea of ​​the nature of the breathing process. This is understood as the ratio of the volume of carbon dioxide released to the volume of oxygen absorbed during respiration (C02:02).[...]

The efficiency of the cardiorespiratory apparatus of fish, its reserve capabilities, and the lability of frequency and amplitude parameters depend on the species and ecological characteristics of the fish. When the temperature increased by the same amount (from 5 to 20°C), the respiratory rate of pike perch increased from 25 to 50 per minute, for pike from 46 to 75, and for ide from 63 to 112 per minute. Oxygen consumption increases in parallel with increasing frequency, but not depth of breathing. The largest number of respiratory movements to pump a unit volume of water is produced by the mobile ide, and the least by the less active oxyphilic pike perch, which positively correlates with the intensity of gas exchange in the studied species. According to the authors, the ratio of the maximum volume of ventilation and the corresponding oxygen utilization coefficient determines the maximum energy capabilities of the body. At rest, the highest intensity of gas exchange and volume of ventilation were in oxyphilic pike perch, and under functional load (motor activity, hypoxia) - in ide. At low temperatures, the increase in ventilation volume in ide in response to hypoxia was greater than at high temperatures, namely: 20-fold at 5°C and 8-fold at 20°C. In Orthologus thioglossy, under hypoxia (40% saturation), the volume of water pumped through the gills changes to a lesser extent: at 12°C it increases 5 times, and at 28°C - 4.3 times.[...]

The indicators of carbohydrate metabolism during adaptive exogenous hypoxia, i.e., during mild to moderate oxygen deficiency in the environment, have been much less fully studied. However, the limited experimental data available show that in this case, there is an increased use of glycogen in the muscles, an increase in lactic acid and blood sugar. As would be expected, the level of water oxygen saturation at which these shifts occur varies across species. For example, in the lamprey, hyperglycemia was observed when the oxygen content decreased by only 20% from the initial level, and in 1 abeo karepvk the blood sugar concentration remained constantly low even at 40% oxygen saturation of the water, and only a further decrease in saturation led to a rapid increase in blood sugar levels. An increase in blood sugar and lactic acid has been noted during hypoxia in tench. A similar reaction to hypoxia was noted in channel catfish. In the first of these studies, at 50% saturation of water with oxygen, an increase in the content of lactic acid was detected in fish, which continued in the first hour of normoxia, i.e., after the fish returned to normal oxygen conditions. The restoration of biochemical parameters to normal occurred within 2-6 hours, and an increase in lactate content and respiratory coefficient from 0.8 to 2.0 indicated an increase in anaerobic glycolysis.

The respiratory quotient (RC) is the ratio of the volume of carbon dioxide released to the volume of oxygen absorbed over a certain time. If during the metabolic process only carbohydrates are oxidized in the body, then the respiratory coefficient will be equal to 1. This can be seen from the following formula:

Consequently, to form one molecule of CO 2 during the metabolism of carbohydrates, one molecule of O 2 is required. Since, according to the Avogadro-Gerard law, equal numbers of molecules at the same temperature and pressure occupy equal volumes. Therefore, the respiratory coefficient for the oxidation of carbohydrates will be equal to 1:

For fats it will be:

The oxidation of one molecule of fat requires 81.5 molecules of oxygen, and the oxidation of 1 gram molecule of fat requires 81.5 x 22.4 liters of oxygen, that is, 1825.6 liters of O 2, where 22.4 is the volume of one gram molecule in liters. A gram molecule of fat is equal to 890 g, then 1 liter of oxygen oxidizes 487 g fat. 1 g of fat, upon complete oxidation, releases 38.945 kJ (9.3 kcal)*, and 0.487 gives 18.551 kJ. Therefore, the caloric equivalent of 1 liter of oxygen with a respiratory coefficient of 0.7 will be equal to 18.551 kJ. Under normal conditions, respiratory

Determination of the respiratory coefficient (RK) of plants.

The respiratory coefficient of plants is the ratio of the amount of carbon dioxide released during respiration to the amount of oxygen absorbed during the same time.

The value of DC depends on the chemical nature of the respiratory substrate, the biological characteristics of plants, oxygen supply conditions and other reasons.

This work examines the DC value depending on the respiratory substrate. If the substrate is carbohydrates, then DC = 1; if the substrate is more hydrogen-rich fats or some proteins, DC is less than 1 and usually equal to 0.3-0.7; when the substrates are organic acids, DC is greater than 1.

Progress.

The test tube is filled halfway with sprouted seeds, closed with a stopper into which a thin glass tube bent at a right angle is inserted. The horizontal elbow of the tube should be graduated, or a strip of graph paper should be attached to it. Insert a drop of Vaseline oil or water into the tube.

The device is placed in a glass with cotton wool (so that it does not heat up from your hands). Observe the movement of the meniscus in a glass tube. If DC = 1, the drop remains motionless in the tube. If DC is greater or less than 1, the drop in the tube will move. It is necessary to determine the displacement of the drop three times in 5 minutes and find the average value (A).

A is the difference between the volumes of absorbed O2 and released CO2.

Remove the stopper, ventilate the test tube, and place a disk of filter paper moistened with a 20% KOH solution into the upper part of the test tube. Close the plug, introduce a drop of oil, determine the movement of the drop over three five-minute intervals, and calculate the average value (B). Alkali absorbs CO2 released during breathing. The movement of the drop now corresponds to the absorption of O2.

Calculations can be made using the following formula:

Equipment and reagents:

A wide flat-bottomed test tube with a stopper into which a capillary outlet tube is inserted, a wide glass with cotton wool, an hourglass for 5 minutes, tweezers, circles of filter paper, petroleum jelly, 20% KOH solution, sprouted seeds (wheat, sunflower, castor oil, beans , etc.).

Review questions:

Terms.

Amylase- enzymes of the hydrolase class, catalyzing the hydrolysis of reserve polysaccharides (starch, glycogen). Amylases are found in animals (pancreatic juice), in higher plants (sprouted seeds) and in microorganisms. Depending on the nature of the action, there are a-amylases (cleave the a-1,4-bonds in the polysaccharide molecule), (3-amylases (sequentially cleave maltose from the non-reducing ends of the polymer chains) and glucoamylases (cleave the polysaccharide to form free glucose).

Glycolysis- Embden-Meyerhof-Parnaea pathway, an enzymatic anaerobic process of non-hydrolytic breakdown of carbohydrates to PVC. This is the phylogenetically most ancient pathway, widespread in nature, and plays an important role in the metabolism of living organisms. Provides the cell with energy in conditions of insufficient oxygen supply.

Dehydrogenase- enzymes of the oxidoreductase class, catalyzing reactions of hydrogen abstraction from one substrate and transferring it to another. Participate in the processes of catabolism of all types of nutrients. The coenzymes of dehydrogenases are usually NAD, NADR, | FAD, FMN. Reactions involving dehydrogenases underlie biological oxidation, which is closely related to the provision of energy to cells.

Dehydrogenases are anaerobic- two-component enzymes, the coenzyme of which can be NAD+ and NADP+. When the substrate is oxidized, NAD+ is converted to the reduced form of NADH. Anaerobic dehydrogenases transfer hydrogen, that is, electrons and protons, to various intermediate carriers and aerobic dehydrogenases. The substrate specificity of an enzyme depends on its protein part. Many dehydrogenases contain divalent metal ions, such as Zn.

Aerobic dehydrogenases- two-component enzymes, also called flavoproteins. In addition to proteins, they contain a prosthetic group - riboflavin (vitamin Br). The electron donors of aerobic dehydrogenases are anaerobic dehydrogenases, and the acceptors are quinones, cytoquinones, and oxygen.

Breath- inherent in all organs, tissues and cells of plants; carried out due to carbohydrates. The intensity of respiration is determined by the amount of absorbed O2 or released CC and depends on ontogenesis, morphological features, temperature, etc.

Respiratory coefficient- the ratio of the volume of CO2 released from the body during respiration to the volume of O2 absorbed during the same time; characterizes the features of gas exchange and metabolism in living organisms. The respiratory coefficient depends on the chemical nature of the respiratory substrate, the content of CO2 and O2 in the atmosphere, etc.

Catalase- an enzyme of the oxidoreductase class, catalyzes the decomposition reaction of hydrogen peroxide (H2O2), toxic to the body, with the formation of H20 and O2. A widespread enzyme, it is found in specialized organelles - peroxisomes and glyoxysomes. The prosthetic group of catalase is heme, which contains an iron atom. Molecular weight 250000.

Oxidases- enzymes of the class of oxidoreductases, catalyzing redox reactions in which atmospheric oxygen serves as hydrogen acceptors. In this case, water or H2O2 is formed. The coenzyme of many oxidases are derivatives of vitamin B2 - FAD or FMN. Oxidases are widespread in nature and play an important role in the catabolism and detoxification of various substances.

Oxidative phosphorylation- the process of synthesis of ATP molecules from ADR and inorganic phosphate due to the energy of oxidation of molecules of organic substances. Occurs only in living systems. This process was discovered in 1930 by V. A. Engelhard and is associated with the transfer of electrons along the electron transport chain built into the inner membrane of mitochondria.

The ratio of the volume of carbon dioxide released to the volume of oxygen absorbed is called the respiratory coefficient.

DK = CO 2 (l)/O 2 (l)

The respiratory coefficient characterizes the type of nutrients predominantly oxidized in the body at the time of its determination. It is calculated based on the formulas of chemical oxidative reactions.

For carbohydrates:

C 6 H 12 O 2 + 6 O 2 o - 6 CO 2 + 6 H 2 O;

DC = (6 volumes of CO 2)/(6 volumes of O 2) = 1

For fats:

2C 15 H48,O 6 + 145O 2 o - 102CO 2 + 98H 2 O;

DK = (102 volumes of CO 2)/(145 volumes of O 2) = 0.703

For proteins the calculation is somewhat difficult, since proteins in the body are not completely oxidized. Some nitrogen in urea (NH 2) 2 CO 2 is excreted from the body in urine, sweat and feces. Therefore, to calculate the DC during protein oxidation, you should know the amount of protein received from food and the amount of excreted nitrogen-containing “wastes”. It has been established that for the oxidation of carbon and hydrogen during protein catabolism and the formation of 77.5 volumes of carbon dioxide, 96.7 volumes of oxygen are required. Therefore, for proteins:

DC = (77.5 volumes of CO 2)/(96.7 volumes of O2) = 0.80

With mixed food the respiratory coefficient is 0.8-0.9.

Respiratory coefficient during muscular work. The main source of energy during intense muscular work is carbohydrates. That's why while working DC is approaching unity.

Immediately upon completion of work DK can increase sharply. This phenomenon reflects compensatory processes aimed at removing excess carbon dioxide from the body, the source of which is the so-called non-volatile acids.

Over time upon completion of work DC may drop sharply compared to normal. This is due to a decrease in the release of carbon dioxide by the lungs due to its compensatory retention by blood buffer systems, which prevent a shift in pH towards the main side.

In about an hour after the work is completed, the DC becomes normal.

Caloric equivalent of oxygen. A certain respiratory coefficient corresponds to a certain caloric equivalent of oxygen, i.e. the amount of heat that is released during the complete oxidation of 1 g of a nutrient (to final products) in the presence of 1 liter of oxygen.

The caloric equivalent of oxygen during the oxidation of proteins is 4.8 kcal (20.1 kJ), fat - 4.7 kcal (19.619 kJ), carbohydrates - 5.05 kcal (21.2 kJ).

Initially, gas exchange in humans and animals was determined by the Krogh method in special closed-type chambers (M.N. Shaternikov’s respiratory chamber).

Currently, complete gas analysis is carried out using the Douglas-Haldane open respiratory method. The method is based on collecting exhaled air into a special receiver (an airtight bag) with subsequent determination of its total amount and the content of oxygen and carbon dioxide in it using gas analyzers.

No. 51 Basic metabolism and methods for its determination. Conditions for determining basal metabolism and factors influencing its value. Specific dynamic action of food. M. Rubner's surface law.

BX- the minimum amount of energy required to ensure normal life activity in conditions of relative physical and mental peace. This energy is spent on cellular metabolic processes, blood circulation, respiration, excretion, maintaining body temperature, the functioning of vital nerve centers of the brain, and the constant secretion of endocrine glands.

The liver consumes 27% of the basal metabolic energy, the brain - 19%, muscles - 18%, kidneys - 10%, heart - 7%, all other organs and tissues - 19%.

Methods for determining basal metabolism.

Calculation of basal metabolic rate using tables. Special tables make it possible to determine the average level of a person’s basal metabolic rate based on height, age and body weight. By comparing these values ​​with the results obtained from studying the working exchange using instruments, it is possible to calculate the difference equivalent to the energy expenditure to perform the work.

Calculation of basal metabolism using hemodynamic parameters (Reed's formula). The calculation is based on the relationship between blood pressure, pulse rate and body heat production. The formula makes it possible to calculate the percentage of deviation of the basal metabolic rate from the norm. Acceptable deviation is ±10 %.

PO = 0.75 (HR + PP 0.74) - 72,

where PO is the percentage of deviations; HR - heart rate

(pulse); PP - pulse pressure.

To determine the compliance of the basal exchange with normative data on hemodynamic parameters, there are special nomograms.

Energy consumption at rest by different tissues of the body is not the same. Internal organs spend energy more actively, muscle tissue less actively. The intensity of basal metabolism in adipose tissue is 3 times lower than in the rest of the cellular mass of the body. People with low body weight produce more heat per kg of body weight than people with high body weight. If we calculate the energy release per 1 m2 of body surface, then this difference almost disappears. According to another Rubner's rule, basal metabolic rate is approximately proportional to body surface area for different animal species and humans.

Seasonal fluctuations in the value of basal metabolism were noted - its increase in spring and decrease in winter. The amount of basal metabolism is influenced by previous muscular work and the state of the endocrine glands.

Conditions for determining the basal metabolic rate.

Any work - physical or mental, as well as food intake, fluctuations in ambient temperature and other external and internal factors that change the level of metabolic processes, entail an increase in energy expenditure.

Therefore, basal metabolism is determined in strictly controlled, artificially created conditions: in the morning, on an empty stomach (12-14 hours after the last meal), in a supine position, with complete muscle relaxation, in a state of quiet wakefulness, in conditions of temperature comfort (18-18 20 °C). 3 days before the study, protein foods are excluded from the diet. The basic metabolism is expressed by the amount of energy consumed at the rate of 1 kcal per 1 kg of body weight per hour.

Factors that determine the amount of basal metabolism. Basic metabolism depends on the age, height, body weight, and gender of a person. The most intense basal metabolism per 1 kg of body weight is observed in children (in newborns - 53 kcal/kg per day, in children of the first year of life - 42 kcal/kg). The average basal metabolic rate in adult healthy men is 1300-1600 kcal/day; in women these values ​​are 10% lower. This is due to the fact that women have less mass and body surface area.

Specific dynamic action of food- an increase in the body’s energy expenditure due to the intake, digestion and assimilation of food. The specific dynamic effect of food is that energy is also consumed to digest food, even in the absence of muscle activity. In this case, the greatest consumption is caused by the digestion of proteins. Proteins have a maximally enhancing effect on metabolism, they increase it by 40%, carbohydrates and fats increase it by only 5%. With normal nutrition, the daily consumption for the specific dynamic action of food in an adult is about 200 calories.

Rubner's body surface law. The dependence of the basal metabolic rate on the body surface area was shown by the German physiologist Rubner for various animals. According to this rule, the intensity of the basal metabolic rate is closely related to the size of the body surface: in warm-blooded organisms with different body sizes, the same amount of heat is dissipated from 1 m 2 of surface.

Thus, the law of body surface states: the energy expenditure of a warm-blooded organism is proportional to the body surface area.

With age, the basal metabolic rate steadily decreases. The average basal metabolic rate in a healthy person is approximately 1 kcal/(kg-h).

No. 52 Working energy metabolism. Energy expenditure of the body during various types of labor. Methods for determining working exchange.

The total energy expenditure of a person depends on the state of the body and muscle activity.

Muscular work involves significant energy expenditure ( working energy metabolism), on the one hand, and an increase in heat production, on the other. In a calmly lying person, heat production is 35 kcal/(gm 2). If the subject takes a sitting position - by 42%; in a standing position - by 70%, and with calm, leisurely walking, heat production increases by 180%. With muscle loads of average intensity, the efficiency of muscle work is about 24%. Of the total amount of energy expended by working muscles, 43% is spent on activating contraction, and all this energy is converted into heat. Only 57% of the total energy goes to work reduction.

The difference between the energy consumption during physical activity and the energy consumption of the basal metabolic rate constitutes a work increase, which is greater the more intense the work. Working gain is all the remaining energy that the body spends during the day on physical and mental activity.

The sum of the basic exchange and the working increase constitutes the gross exchange. The sum of gross metabolism and the specific dynamic action of food is called general metabolism. The maximum permissible workload for a given person, constantly performed by him for a long time, should not exceed the level of basal metabolism in energy consumption by more than 3 times. During short-term exercise, energy is released due to the oxidation of carbohydrates.

During prolonged muscular exercise, the body breaks down primarily fats, providing 80% of the energy required. In trained athletes, the energy of muscle contractions is provided exclusively by fat oxidation. For a person engaged in physical labor, energy costs increase in proportion to the intensity of work.

Based on energy costs, all professions are divided into several groups, each of which is characterized by its own daily energy consumption.

Physical activity rate. An objective physical criterion that determines the adequate amount of energy expenditure for specific professional groups of people is the physical activity coefficient (the ratio of total energy expenditure for all types of life activity to the value of basal metabolism, i.e. energy expenditure at rest). The values ​​of the physical activity coefficient are the same for men and women, but due to the lower body weight in women and, accordingly, the basal metabolism, the energy expenditure of men and women in groups with the same physical activity coefficient is different.

Group I- workers primarily in mental labor: scientists, students of humanities. Very light physical activity; physical activity coefficient 1.4; energy consumption 1800-2450 kcal/day.

Group II- workers engaged in light physical labor: drivers of trams, trolleybuses, service workers, nurses, orderlies. Light physical activity; physical activity coefficient 1.6; energy consumption 2100-2800 kcal/day.

Group III- medium-heavy workers: mechanics, adjusters, bus drivers, surgeons. Average physical activity; physical activity coefficient 1.9; energy consumption 2500-3300 kcal/day.

Group IV- workers of heavy physical labor: construction workers, metallurgists. High physical activity; physical activity coefficient 2.2; energy consumption 2850-3850 kcal/day.

Group V- workers of particularly hard labor, only men: machine operators, agricultural workers during the sowing and harvesting periods, miners, fellers, concrete workers, masons, diggers, loaders of non-mechanized labor, reindeer herders, etc. Very high physical activity; physical activity coefficient 2.5; energy consumption 3750-4200 kcal/day.

For each labor group, the average values ​​of the balanced needs of a healthy person for energy and nutrients have been determined, which are slightly different for men and women.

No. 53 Human body temperature and its daily fluctuations. Heat balance of a homeothermic organism. Temperature diagram of the human body. Methods for measuring human body temperature.

Homeothermy. In the process of evolution, higher animals and humans have developed mechanisms capable of maintaining body temperature at a constant level, regardless of the ambient temperature. The temperature of their internal organs fluctuates between 36-38 °C, promoting the optimal course of metabolic processes, catalyzing most enzymatic reactions and influencing their speed within certain limits.

A constant temperature is also necessary to maintain normal physical and chemical parameters - blood viscosity, surface tension, colloid-osmotic pressure, etc. Temperature also affects excitation processes, the speed and intensity of muscle contraction, the processes of secretion, absorption and protective reactions of cells and tissues.

Homeothermic organisms have developed regulatory mechanisms that make them less dependent on environmental conditions. They are able to avoid overheating when the air temperature is too high and hypothermia when the air temperature is too low.

The optimal body temperature for humans is 37 °C; the upper lethal temperature is 43.4 °C. At higher temperatures, intracellular protein denaturation and irreversible death begin; the lower lethal temperature is 24 °C. Under extreme conditions of sudden changes in ambient temperature, homeothermic animals react with a stress response (temperature - heat or cold - stress). With the help of these reactions, such animals maintain an optimal level of body temperature. Homeothermy in humans is developed throughout life.

The body temperature of humans, as well as higher animals, is subject to more or less regular daily fluctuations even under the same conditions of nutrition and physical activity.

Body temperature during the day is higher than at night, and during the day fluctuates between 0.5-3 ° C, decreasing to a minimum level at 3-4 am and reaching a maximum at 16-18 pm. The daily rhythm of the temperature curve is not directly related to the change in periods of activity and rest, since it persists even if a person is constantly at complete rest. This rhythm is maintained without any external regulatory factors; it is inherent in the organism itself and represents a truly endogenous rhythm.

Women have pronounced monthly cycles of body temperature fluctuations. the temperature rises after eating (a specific dynamic effect of food), during muscle work, and nervous tension.

Body temperature pattern, which is determined by different levels of metabolism in different organs. Body temperature in the armpit is 36.8 °C, on the palmar surfaces of the hand - 25-34 °C, in the rectum - 37.2-37.5 °C, in the oral cavity - 36.9 °C. The lowest temperature is observed in the fingers of the lower extremities, and the highest in the liver.

At the same time, even in the same organ there are significant temperature gradients, and its fluctuations range from 0.2 to 1.2 °C. So, in the liver the temperature is 37.8-38 °C, and in the brain - 36.9-37.8 °C. Significant temperature fluctuations are observed during muscle activity. In humans, intense muscular work leads to an increase in the temperature of contracting muscles by 7 °C.

When a person bathes in cold water, the temperature of the foot drops to 16 °C without any unpleasant sensations.

Individual features of the body temperature pattern:

A healthy person has a relatively constant body temperature pattern;

Features of the temperature pattern are genetically determined, primarily by the individual intensity of metabolic processes;

Individual characteristics of the body temperature pattern are determined by the influence of humoral (hormonal) factors and the tone of the autonomic nervous system;

The temperature pattern of the body is improved in the process of education, determined by lifestyle and especially by hardening. At the same time, it is dynamic within certain limits, depending on the characteristics of the profession, environmental conditions, character and other factors.

No. 54 Mechanisms of heat production. Metabolism as a source of heat formation. The role of individual organs in heat production and regulation of this process.

Heat generation centers. Heat generation centers were found in the area of ​​the lateral dorsal hypothalamus. Their destruction leads to the fact that animals lose the ability to maintain a constant body temperature in conditions of low ambient temperature. Their body temperature begins to drop under these conditions, and the animals go into a state of hypothermia. Electrical stimulation of the corresponding centers of the hypothalamus causes the following syndrome in animals: 1) narrowing of the superficial vessels of the skin. Vasoconstriction is achieved by activation of the sympathetic centers of the posterior hypothalamus.; 2) piloerection - the reaction of straightening body hair.; 3) muscle tremors - increases the amount of heat production by 4–5 times. The shivering motor center is located in the dorsomedial part of the posterior hypothalamus. It is inhibited by increased external temperature and excited when it decreases. Impulses from the shivering center cause a generalized increase in muscle tone. Increased muscle tone leads to the emergence of rhythmic reflexes from muscle spindles, which causes trembling; 4) increased secretion of the adrenal glands.

Interaction of thermoregulation centers. Between the centers of heat transfer of the anterior hypothalamus and the centers of heat production of the posterior hypothalamus there are reciprocal relationships. When the activity of heat production centers increases, the activity of heat transfer centers is inhibited and vice versa. When body temperature decreases, the activity of neurons in the posterior hypothalamus is activated; When body temperature rises, neurons in the anterior hypothalamus are activated.

Mechanisms of heat production. When the ambient temperature decreases, efferent impulses from neurons of the posterior hypothalamus spread to α-motoneurons of the spinal cord. These influences lead to contraction of skeletal muscles. When muscles contract, ATP hydrolysis increases. As a result, voluntary muscle activity increases.

At the same time, upon cooling, the so-called thermoregulatory muscle tone. Thermoregulatory tone represents a kind of microvibration of muscle fibers. As a result, heat production increases by 20-45% from the initial level. With more significant cooling, the thermoregulatory tone turns into cold muscle tremors. Cold shivering is an involuntary rhythmic activity of superficial muscles. As a result, heat production increases 2-3 times compared to the initial level.

The mechanisms of muscle tremors are associated with the spread of excitation from the hypothalamus through the tegmentum of the midbrain and through the red nucleus to the α-motoneurons of the spinal cord and from them to the corresponding muscles.

At the same time, during cooling, oxidation processes are activated in skeletal muscles, liver and brown fat and the efficiency of oxidative phosphorylation decreases. Due to these processes, the so-called non-contractile thermogenesis, heat production can increase 3 times.

Regulation of non-contractile thermogenesis is carried out by activation of the sympathetic nervous system, hormones of the thyroid gland and the adrenal medulla.

No. 55 Heat transfer mechanisms. Ways the body releases heat. Physiological mechanisms of heat transfer.

Maintaining body temperature at a level optimal for metabolism is carried out due to the regulatory influence of the central nervous system. Due to nervous and direct humoral influences, in which a number of oligopeptides, such as bombesin, are involved, processes are formed in the functional system under consideration aimed at restoring the formed changes in the temperature pattern of the body. These processes include the mechanisms of heat production and heat transfer.

Heat transfer centers. Heat transfer centers were found in the area of ​​the anterior nuclei of the hypothalamus. The destruction of these structures leads to the fact that animals lose the ability to maintain a constant body temperature in conditions of high ambient temperature. At the same time, their body temperature begins to increase, the animals go into a state of hyperthermia, and hyperthermia can develop even at room temperature. Irritation of these structures through implanted electrodes with electric current causes a characteristic syndrome in animals: shortness of breath, dilation of superficial skin vessels, and a drop in body temperature. The muscle tremors caused by pre-cooling stop.

Heat dissipation(physical thermoregulation) is determined by physical processes:

Movement of warm air from the surface of the body by contact or distant convection;

Thermal radiation (radiation);

Evaporation of fluid from the surface of the skin and upper respiratory tract

Discharge of urine and feces.

Physical thermoregulation is carried out in the following ways.

Contact convection- direct exchange of heat between two objects with different temperatures that are in direct contact with each other.

Distant convection- the transition of heat into a stream of air, which moves near the surface of the body and, heating up, is replaced by a new, colder one.

Radiation- heat transfer by radiation of electromagnetic energy into

in the form of infrared rays.

Heat transfer regulation.Convection, heat radiation And evaporation heat is directly proportional to the heat capacity of the environment.

Heat dissipation depends on the volume of body surface. It is known that many animals curl up into a ball in the cold, occupying a smaller volume. The processes of convection, radiation and evaporation of heat depend on the properties of the skin. The fur on the skin of animals prevents heat transfer.

Vascular reactions during overheating. All physical processes of heat transfer in humans are based on physiological processes associated with changes in the lumen of the surface vessels of the skin under the influence of ambient temperature. When exposed to high temperatures, blood vessels expand; when exposed to low temperatures, they narrow. These reactions are carried out due to the activation of the autonomic nervous system - the parasympathetic department in the first case and the sympathetic one in the second.

Bradykinin, which is produced by the sweat glands through cholinergic sympathetic fibers, takes part in the mechanisms of skin vasodilation.

Heat transfer in an aqueous environment. Heat transfer processes depend on the physical properties of the environment. The processes of heat transfer, as well as heat production, change most complexly in the aquatic environment. Cool water has the greatest heat capacity. Evaporation is eliminated in water. At the same time, water exerts physical pressure on the integument of the body, and a redistribution of body weight occurs. Water temperature has an irritating effect on skin receptors and interoreceptors.

Sweating. The most significant mechanism for heat loss is sweating. With 1 g of steam, the body loses about 600 calories of heat. Sweating is essential for maintaining an optimal level of body temperature in high ambient temperatures, especially in hot countries. It has been established that not all people are equally capable of increased sweating in conditions of elevated temperature.

No. 56 A functional system that maintains the blood temperature optimal for metabolism. Characteristics of its key mechanisms.

The functional system that determines the optimal body temperature for metabolism combines two subsystems: internal endogenous self-regulation and goal-directed behavior. Endogenous mechanisms of self-regulation due to the processes of heat production and heat release determine the maintenance of body temperature necessary for metabolism. Functional system:

Beneficial adaptive outcome

The indicator for which this functional system works is blood temperature. On the one hand, it ensures the normal course of metabolic processes, and on the other, it is itself determined by their intensity.

For the normal course of metabolic processes, homeothermic animals, including humans, are forced to maintain body temperature at a relatively constant level. However, this constancy is conditional. The temperature of various organs is subject to fluctuations, the boundaries of which depend on the time of day, the functional state of the body, the thermal insulation properties of clothing, etc.