In the totality of chemical reactions, the exchange of substances and energy occurs, which is so necessary for the functioning of the body. The main stages are distinguished here - these are preparatory and metabolism. At the first stage, the substance, entering the body through the alimentary route, undergoes a chemical transformation and then enters the blood and cells. The second stage is metabolism - the compounds entering the cells also undergo chemical transformations.
The metabolism and energy in the cell performs specific functions. This is the extraction of energy from the environment and its conversion into high-energy compounds necessary to provide cells with energy needs. During this process, intermediate compounds are formed, which are precursors of high-molecular cellular components, as well as the synthesis of proteins, lipids, nucleic acids and sugars. In addition, this process is accompanied by the destruction and synthesis of special biomolecules. In simpler terms, the most complex types degrade into simpler ones, and the body, spending energy on this transformation, synthesizes cellular components.
Metabolism of substances and energy allows the body to reproduce and grow, maintains its structures and responds to environmental influences. To understand its essence, you need to take into account the cellular energetic identity. The cell is isothermal, that is, all parts of the cells have approximately the same temperature. Different cells practically do not differ from each other in pressure.
Metabolism of substances and energy is not only the basis of all life processes, but it is one of the most important specific characteristics that distinguish living matter from dead matter. All elements that naturally enter the body are converted into the tissue's own substances, and subsequently into final products.
Metabolism of substances and energy takes place not only in the cell, but also in the intercellular fluid, and the constancy of its composition is maintained with the help of blood circulation. During the passage of blood through the capillaries, plasma can be completely renewed 40 times. Enzymes play an important role in these processes. They act and also regulate metabolic pathways.
In absolutely all living organisms, regardless of their primitiveness or, conversely, complexity, the basis of all life is the metabolism and energy in the body. It determines the entire life cycle, from birth, growth, aging and ending with death.
Various processes occur in the body - fats, water, mineral salts, carbohydrates. These include the creation of new structures and compounds characteristic of each organism. The results are the release of energy necessary for the life of the body, tissues and cells. The starting products are the formation of ammonia, compounds of sodium, chlorine, fluorine and carbon dioxide. Metabolism of substances and energy in the body ends with the stage of removing waste compounds from the body, in the implementation of which the blood, lungs, and urinary organs participate.
The law of conservation of matter and energy is the theoretical basis for the most important method for studying processes such as metabolism and energy or establishing balance. That is, the amount of energy and substances that enter and are released from the body in the form of heat and other metabolic end products is determined. To determine their total balance, knowledge of the exact chemical methods and ways of excretion of various elements from the body is required. Energy balance is determined by the caloric content of nutrients and the amount of heat generated, which can be measured and calculated.
Metabolism and energy, or metabolism, - a set of chemical and physical transformations of substances and energy that occur in a living organism and ensure its vital activity. Metabolism of matter and energy constitutes a single whole and is subject to the law of conservation of matter and energy.
Metabolism consists of the processes of assimilation and dissimilation. Assimilation (anabolism)- the process of absorption of substances by the body, during which energy is consumed. Dissimilation (catabolism)- the process of decomposition of complex organic compounds that occurs with the release of energy.
The only source of energy for the human body is the oxidation of organic substances supplied with food. When food products are broken down into their final elements - carbon dioxide and water - energy is released, part of which goes into mechanical work performed by muscles, the other part is used for the synthesis of more complex compounds or accumulates in special high-energy compounds.
Macroergic compounds are substances whose breakdown is accompanied by the release of a large amount of energy. In the human body, the role of high-energy compounds is performed by adenosine triphosphoric acid (ATP) and creatine phosphate (CP).
PROTEIN METABOLISM.
Proteins(proteins) are high-molecular compounds built from amino acids. Functions:
Structural or plastic function is that proteins are the main component of all cells and intercellular structures. Catalytic or enzymatic The function of proteins is their ability to accelerate biochemical reactions in the body.
Protective function proteins manifests itself in the formation of immune bodies (antibodies) when a foreign protein (for example, bacteria) enters the body. In addition, proteins bind toxins and poisons that enter the body, and ensure blood clotting and stop bleeding in case of wounds.
Transport function involves the transfer of many substances. The most important function of proteins is the transmission hereditary properties , in which nucleoproteins play a leading role. There are two main types of nucleic acids: ribonucleic acids (RNA) and deoxyribonucleic acids (DNA).
Regulatory function proteins is aimed at maintaining biological constants in the body.
Energy role Proteins are responsible for providing energy for all life processes in the body of animals and humans. When 1 g of protein is oxidized, on average, energy is released equal to 16.7 kJ (4.0 kcal).
Protein requirement. The body constantly breaks down and synthesizes proteins. The only source of new protein synthesis is food proteins. In the digestive tract, proteins are broken down by enzymes into amino acids and are absorbed in the small intestine. From amino acids and simple peptides, cells synthesize their own protein, which is characteristic only of a given organism. Proteins cannot be replaced by other nutrients, since their synthesis in the body is possible only from amino acids. At the same time, protein can replace fats and carbohydrates, i.e., be used for the synthesis of these compounds.
Biological value of proteins. Some amino acids cannot be synthesized in the human body and must be supplied with food in finished form. These amino acids are commonly called irreplaceable, or vitally necessary. These include: valine, methionine, threonine, leucine, isoleucine, phenylalanine, tryptophan and lysine, and in children also arginine and histidine. A lack of essential acids in food leads to disturbances in protein metabolism in the body. Nonessential amino acids are mainly synthesized in the body.
Proteins containing all the necessary amino acids are called biologically complete. The highest biological value of proteins is milk, eggs, fish, and meat. Biologically deficient proteins are those that lack at least one amino acid that cannot be synthesized in the body. Incomplete proteins are proteins from corn, wheat, and barley.
Nitrogen balance. Nitrogen balance is the difference between the amount of nitrogen contained in human food and its level in excreta.
Nitrogen balance- a condition in which the amount of nitrogen excreted is equal to the amount entered into the body. Nitrogen balance is observed in a healthy adult.
Positive nitrogen balance- a condition in which the amount of nitrogen in the body’s secretions is significantly less than its content in food, that is, nitrogen retention in the body is observed. A positive nitrogen balance is observed in children due to increased growth, in women during pregnancy, during intense sports training leading to an increase in muscle tissue, during the healing of massive wounds or recovery from serious illnesses.
Nitrogen deficiency(negative nitrogen balance) is observed when the amount of nitrogen released is greater than its content in the food entering the body. Negative nitrogenbalance is observed during protein starvation, feverish conditions, and disorders of the neuroendocrine regulation of protein metabolism.
Protein breakdown and urea synthesis. The most important nitrogenous products of protein breakdown, which are excreted in urine and sweat, are urea, uric acid and ammonia.
FAT METABOLISM.
Fats are divided on simple lipids(neutral fats, waxes), complex lipids(phospholipids,glycolipids, sulfolipids) and steroids(cholesterol andetc.). The bulk of lipids in the human body are represented by neutral fats. Neutral fats Human food is an important source of energy. When 1 g of fat is oxidized, 37.7 kJ (9.0 kcal) of energy is released.
The daily requirement of an adult for neutral fat is 70-80 g, for children 3-10 years old - 26-30 g.
Energy-neutral fats can be replaced with carbohydrates. However, there are unsaturated fatty acids - linoleic, linolenic and arachidonic, which must necessarily be contained in the human diet, they are called Not replaceable bold acids.
Neutral fats that make up food and human tissues are represented mainly by triglycerides containing fatty acids - palmitic,stearic, oleic, linoleic and linolenic.
The liver plays an important role in fat metabolism. The liver is the main organ in which the formation of ketone bodies (beta-hydroxybutyric acid, acetoacetic acid, acetone) occurs. Ketone bodies are used as a source of energy.
Phospho- and glycolipids are found in all cells, but mainly in nerve cells. The liver is practically the only organ that maintains the level of phospholipids in the blood. Cholesterol and other steroids can be obtained from food or synthesized in the body. The main site of cholesterol synthesis is the liver.
In adipose tissue, neutral fat is deposited in the form of triglycerides.
Formation of fats from carbohydrates. Excessive intake of carbohydrates from food leads to the deposition of fat in the body. Normally, in humans, 25-30% of food carbohydrates are converted into fats.
Formation of fats from proteins. Proteins are plastic materials. Only under extreme circumstances are proteins used for energy purposes. The conversion of protein to fatty acids most likely occurs through the formation of carbohydrates.
CARBOHYDRATE METABOLISM.
The biological role of carbohydrates for the human body is determined primarily by their energy function. The energy value of 1 g of carbohydrates is 16.7 kJ (4.0 kcal). Carbohydrates are a direct source of energy for all cells of the body and perform plastic and support functions.
The daily carbohydrate requirement of an adult is approximately 0.5 kg. The main part of them (about 70%) is oxidized in tissues to water and carbon dioxide. About 25-28% of dietary glucose is converted into fat and only 2-5% of it is synthesized into glycogen - the body's reserve carbohydrate.
The only form of carbohydrates that can be absorbed are monosaccharides. They are absorbed mainly in the small intestine and are transported by the bloodstream to the liver and tissues. Glycogen is synthesized from glucose in the liver. This process is called glycogenesis. Glycogen can be broken down into glucose. This phenomenon is called glycogenolysis. In the liver, new formation of carbohydrates is possible from the products of their breakdown (pyruvic or lactic acid), as well as from the breakdown products of fats and proteins (keto acids), which is designated as glyconeogenesis. Glycogenesis, glycogenolysis and glyconeogenesis are closely interrelated processes occurring in the liver that ensure optimal blood sugar levels.
In the muscles, as well asIn the liver, glycogen is synthesized. The breakdown of glycogen is one of the sources of energy for muscle contraction. When muscle glycogen breaks down, the process proceeds to the formation of pyruvic and lactic acids. This process is called glycolysis. During the rest phase, glycogen re-synthesis occurs from lactic acid in muscle tissue.
Brain contains small reserves of carbohydrates and requires a constant supply of glucose. Glucose in brain tissue is predominantly oxidized, and a small part of it is converted into lactic acid. The energy expenditure of the brain is covered exclusively by carbohydrates. A decrease in the supply of glucose to the brain is accompanied by changes in metabolic processes in the nervous tissue and impaired brain function.
Formation of carbohydrates from proteins and fats (glyconeogenesis). As a result of the transformation of amino acids, pyruvic acid is formed; during the oxidation of fatty acids, acetyl coenzyme A is formed, which can be converted into pyruvic acid, a precursor of glucose. This is the most important general pathway for carbohydrate biosynthesis.
There is a close physiological relationship between the two main sources of energy - carbohydrates and fats. An increase in blood glucose increases the biosynthesis of triglycerides and reduces the breakdown of fats in adipose tissue. Less free fatty acids enter the blood. If hypoglycemia occurs, the process of triglyceride synthesis is inhibited, fat breakdown is accelerated, and free fatty acids enter the blood in large quantities.
WATER-SALT EXCHANGE.
All chemical and physical-chemical processes occurring in the body are carried out in an aquatic environment. Water performs the following important functions in the body: functions: 1) serves as a solvent for food and metabolism; 2) transports substances dissolved in it; 3) reduces friction between contacting surfaces in the human body; 4) participates in the regulation of body temperature due to high thermal conductivity and high heat of evaporation.
The total water content in the adult human body is 50 —60% from its mass, that is, reaches 40—45 l.
It is customary to divide water into intracellular, intracellular (72%) and extracellular, extracellular (28%). Extracellular water is located inside the vascular bed (as part of blood, lymph, cerebrospinal fluid) and in the intercellular space.
Water enters the body through the digestive tract in the form of liquid or water contained in densefood products. Some of the water is formed in the body itself during the metabolic process.
When there is an excess of water in the body, there is general overhydration(water poisoning), when there is a lack of water, metabolism is disrupted. A loss of 10% of water leads to the condition dehydration(dehydration), death occurs when 20% of water is lost.
Along with water, minerals (salts) also enter the body. Near 4% The dry mass of food should consist of mineral compounds.
An important function of electrolytes is their participation in enzymatic reactions.
Sodium ensures the constancy of the osmotic pressure of the extracellular fluid, participates in the creation of bioelectric membrane potential, and in the regulation of the acid-base state.
Potassium provides osmotic pressure of intracellular fluid, stimulates the formation of acetylcholine. A lack of potassium ions inhibits anabolic processes in the body.
Chlorine It is also the most important anion in the extracellular fluid, ensuring constant osmotic pressure.
Calcium and phosphorus are found mainly in bone tissue (over 90%). The calcium content in plasma and blood is one of the biological constants, since even minor changes in the level of this ion can lead to severe consequences for the body. A decrease in the level of calcium in the blood causes involuntary muscle contractions, convulsions, and death occurs due to respiratory arrest. An increase in calcium content in the blood is accompanied by a decrease in the excitability of nervous and muscle tissue, the appearance of paresis, paralysis, and the formation of kidney stones. Calcium is necessary for building bones, so it must be supplied to the body in sufficient quantities through food.
Phosphorus participates in the metabolism of many substances, as it is part of high-energy compounds (for example, ATP). The deposition of phosphorus in the bones is of great importance.
Iron is part of hemoglobin and myoglobin, which are responsible for tissue respiration, as well as enzymes involved in redox reactions. Insufficient intake of iron into the body disrupts hemoglobin synthesis. A decrease in hemoglobin synthesis leads to anemia (anemia). The daily iron requirement of an adult is 10-30 mcg.
Iodine is found in the body in small quantities. However, its significance is great. This is due to the fact that iodine is part of the thyroid hormones, which have a pronounced effect on all metabolic processes, growthand development of the body.
Education and energy consumption.
The energy released during the breakdown of organic substances accumulates in the form of ATP, the amount of which in the tissues of the body is maintained at a high level. ATP is found in every cell of the body. The largest amount is found in skeletal muscles - 0.2-0.5%. Any cell activity always coincides exactly in time with the breakdown of ATP.
The destroyed ATP molecules must be restored. This occurs due to the energy that is released during the breakdown of carbohydrates and other substances.
The amount of energy expended by the body can be judged by the amount of heat it gives off to the external environment.
Methods for measuring energy expenditure (direct and indirect calorimetry).
Respiratory coefficient.
Direct calorimetry is based on the direct determination of heat released during the life of the body. A person is placed in a special calorimetric chamber, in which the entire amount of heat given off by the human body is taken into account. The heat generated by the body is absorbed by water flowing through a system of pipes laid between the walls of the chamber. The method is very cumbersome and can be used in special scientific institutions. As a result, they are widely used in practical medicine. indirect method calorimetry. The essence of this method is that the volume of pulmonary ventilation is first determined, and then the amount of absorbed oxygen and released carbon dioxide. The ratio of the volume of carbon dioxide released to the volume of oxygen absorbed is called respiratory quotient . The value of the respiratory coefficient can be used to judge the nature of oxidized substances in the body.
Upon oxidation carbohydrates respiratory quotient is 1 because for complete oxidation of 1 molecule glucose 6 molecules of oxygen are required to reach carbon dioxide and water, and 6 molecules of carbon dioxide are released:
С 6 Н12О 6 +60 2 =6С0 2 +6Н 2 0
The respiratory coefficient for protein oxidation is 0.8, for fat oxidation - 0.7.
Determination of energy consumption by gas exchange. Quantityheat released in the body when 1 liter of oxygen is consumed - caloric equivalent of oxygen - depends on the oxidation of which substances oxygen is used. Caloric equivalent oxygen during the oxidation of carbohydrates is equal to 21,13 kJ (5.05 kcal), proteins— 20.1 kJ (4.8 kcal), fat - 19.62 kJ (4.686 kcal).
Energy consumption in humans is determined as follows. The person breathes for 5 minutes through a mouthpiece placed in the mouth. The mouthpiece, connected to a bag made of rubberized fabric, has valves They are arranged like this What man breathes freely atmospheric air, and exhales air into the bag. Using gas hours measure the volume of exhaled breath air. The gas analyzer indicators determine the percentage of oxygen and carbon dioxide in the air inhaled and exhaled by a person. The amount of oxygen absorbed and carbon dioxide released, as well as the respiratory quotient, are then calculated. Using the appropriate table, the caloric equivalent of oxygen is determined based on the respiratory coefficient and energy consumption is determined.
Basal metabolism and its significance.
BX- the minimum amount of energy necessary to maintain the normal functioning of the body in a state of complete rest, excluding all internal and external influences that could increase the level of metabolic processes. Basic metabolism is determined in the morning on an empty stomach (12-14 hours after the last meal), in a supine position, with complete muscle relaxation, in temperature comfort conditions (18-20 ° C). The basic metabolism is expressed by the amount of energy released by the body (kJ/day).
In a state of complete physical and mental peace the body consumes energy to: 1) constantly occurring chemical processes; 2) mechanical work performed by individual organs (heart, respiratory muscles, blood vessels, intestines, etc.); 3) constant activity of the glandular-secretory apparatus.
Basic metabolism depends on age, height, body weight, and gender. The most intense basal metabolism per 1 kg of body weight is observed in children. As body weight increases, basal metabolism increases. The average basal metabolic rate for a healthy person is approximately 4.2 kJ (1 kcal) per 1 hour per 1 kg of weight body.
In terms of energy consumption at rest, body tissues are heterogeneous. Internal organs consume 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. Thin people produce more heat per kgbody weight than full.
Women have a lower basal metabolism than men. This is due to the fact that women have less mass and body surface area. According to Rubner's rule, basal metabolism is approximately proportional to the surface area of the body.
Seasonal fluctuations in the value of basal metabolism were noted - it increased in spring and decreased in winter. Muscular activity causes an increase in metabolism in proportion to the severity of the work performed.
Significant changes in the basal metabolism are caused by dysfunctions of organs and systems of the body. With increased thyroid function, malaria, typhoid fever, tuberculosis, accompanied by fever, the basal metabolism increases.
Energy expenditure during physical activity.
During muscular work, the energy expenditure of the body increases significantly. This increase in energy costs constitutes a work increase, which is greater the more intense the work.
Compared to sleep, energy expenditure increases by 3 times when walking slowly, and by more than 40 times when running short distances during competition.
During short-term exercise, energy is consumed through the oxidation of carbohydrates. During prolonged muscular exercise, the body breaks down mainly fats (80% of all necessary energy). 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.
NUTRITION.
Replenishment of the body's energy costs occurs through nutrients. Food should contain proteins, carbohydrates, fats, mineral salts and vitamins in small quantities and in the correct ratio. Digestibilitynutrients dependson the individual characteristics and condition of the body, on the quantity and quality of food, the ratio of its various components, and the method of preparation. Plant foods are less digestible than animal products because plant foods contain more fiber.
A protein diet promotes the absorption and digestibility of nutrients. When carbohydrates predominate in food, the absorption of proteins and fats is reduced. Replacing plant products with products of animal origin enhances metabolic processes in the body. If you give proteins from meat or dairy products instead of vegetable ones, and wheat bread instead of rye bread, then the digestibility of food products increases significantly.
Thus, in order to ensure proper human nutrition, it is necessary to take into account the degree of absorption of foods by the body. In addition, food must necessarily contain all essential (essential) nutrients: proteins and essential amino acids, vitamins,highly unsaturated fatty acids, minerals and water.
The bulk of food (75-80%) consists of carbohydrates and fats.
Diet- the quantity and composition of food products needed by a person per day. It must replenish the body’s daily energy expenditure and include all nutrients in sufficient quantities.
To compile food rations, it is necessary to know the content of proteins, fats and carbohydrates in foods and their energy value. Having this data, it is possible to create a scientifically based diet for people of different ages, genders and occupations.
Diet and its physiological significance. It is necessary to follow a certain diet and organize it correctly: constant hours of meals, appropriate intervals between them, distribution of the daily diet during the day. You should always eat at a certain time, at least 3 times a day: breakfast, lunch and dinner. Breakfast's energy value should be about 30% of the total diet, lunch - 40-50%, and dinner - 20-25%. It is recommended to have dinner 3 hours before bedtime.
Proper nutrition ensures normal physical development and mental activity, increases the performance, reactivity and resistance of the body to environmental influences.
According to the teachings of I.P. Pavlov on conditioned reflexes, the human body adapts to a certain time of eating: appetite appears and digestive juices begin to be released. Proper intervals between meals ensure a feeling of fullness during this time.
Eating three times a day is generally physiological. However, four meals a day are preferable, which increases the absorption of nutrients, in particular proteins, there is no feeling of hunger in the intervals between individual meals and a good appetite is maintained. In this case, the energy value of breakfast is 20%, lunch - 35%, afternoon snack - 15%, dinner - 25%.
Balanced diet. Nutrition is considered rational if the need for food is fully satisfied in quantitative and qualitative terms, and all energy costs are reimbursed. It promotes proper growth and development of the body, increases its resistance to harmful influences of the external environment, promotes the development of the functional capabilities of the body and increases the intensity of work. Rational nutrition involves the development of food rations and diets in relation to various populations and living conditions.
As already indicated, the nutrition of a healthy person is based on daily food rations. The diet and diet of the patient is called a diet. Each diet has certain components of the diet and is characterized by the following characteristics: 1) energy value; 2) chemical composition; 3) physical properties (volume, temperature, consistency); 4) diet.
Regulation of metabolism and energy.
Conditioned reflex changes in metabolism and energy are observed in humans in pre-start and pre-working states. Athletes before the start of a competition, and a worker before work, experience an increase in metabolism and body temperature, an increase in oxygen consumption and the release of carbon dioxide. Can cause conditioned reflex changes in metabolism, energy and thermal processes people have verbal stimulus.
Nervous influence metabolic and energy systems processes in the body carried out in several ways:
Direct influence of the nervous system (through the hypothalamus, efferent nerves) on tissues and organs;
Indirect influence of the nervous system throughpituitary gland (somatotropin);
Indirectinfluence of the nervous system through tropic hormones pituitary gland and peripheral glands of the internal secretion;
Direct influencenervous system (hypothalamus) on the activity of the endocrine glands and through them on metabolic processes in tissues and organs.
The main department of the central nervous system, which regulates all types of metabolic and energy processes, is hypothalamus. A pronounced influence on metabolic processes and heat generation is exerted by internal glands secretion. Hormones of the adrenal cortex and thyroid gland in large quantities increase catabolism, i.e., the breakdown of proteins.
The body clearly demonstrates the close interconnected influence of the nervous and endocrine systems on metabolic and energy processes. Thus, excitation of the sympathetic nervous system not only has a direct stimulating effect on metabolic processes, but also increases the secretion of thyroid and adrenal hormones (thyroxine and adrenaline). Due to this, metabolism and energy are further enhanced. In addition, these hormones themselves increase the tone of the sympathetic nervous system. Significant changes in metabolism And heat exchange occurs when there is a deficiency in the body of hormones of the endocrine glands. For example, a lack of thyroxine leads to a decrease in basal metabolism. This is due to a decrease in oxygen consumption by tissues and a decrease in heat generation. As a result, body temperature decreases.
Hormones of the endocrine glands are involved in the regulation of metabolism And energy, changing the permeability of cell membranes (insulin), activating the body's enzyme systems (adrenaline, glucagon, etc.) and influencing on their biosynthesis (glucocorticoids).
Thus, the regulation of metabolism and energy is carried out by the nervous and endocrine systems, which ensure the body’s adaptation to the changing conditions of its environment.
Metabolism, or as it is also called “metabolism,” is a complex process in which many different systems are involved. This process is so complex and significant for our body that it does not stop for a second.
What is metabolism:
Metabolism in the human body:
A process that involves the breakdown of proteins, fats and carbohydrates, allowing the body to receive the necessary energy to ensure full functioning. Our body functions thanks to the work of metabolic processes in cells. In order for the body to function properly, a sufficient amount of food must be supplied, which is converted into hormones and enzymes as a result of chemical reactions.
What are enzymes:
Enzymes are substances that participate in the process of chemical reactions that break down fats, proteins and carbohydrates. The vital activity of cells is maintained through such processes. Modern research has shown the presence of about 3.5 thousand enzymes. However, enzymes cannot fully carry out processes without the help of hormones, because they are under the control of the hormones themselves.
What are hormones:
Hormones are produced by glands of the endocrine system. They interact with one type of enzyme and inhibit the work of others. It is worth noting that those people who take hormones in the form of tablets cannot fully and correctly control their balance in the body. Hormones act on the body in different ways, improving the functioning of some organs and worsening the functioning of others at the same time. As an example, consider taking hormones to treat joints, which can cause vision problems.
Types of metabolism:
There are 2 types of basic metabolism in the body:
Anabolism
This concept means a chemical process that involves the renewal and formation of new cells, tissues, and organic substances. This process accumulates a certain amount of energy, which is gradually used to protect the body from external, unfavorable factors, such as various diseases and infections, and also promotes the growth of the body as a whole.
Catabolism
The opposite of anabolism, the process in which fats, carbohydrates and proteins are broken down to produce energy. This process is no less important for the body, and is part of the general metabolic process. A catabolic chemical reaction breaks down large molecular formulas into smaller ones, thereby releasing energy. However, in case of an excess of released energy, the body stores it in the form of adipose tissue.
Our body especially needs the substances it needs, such as:
- Water
- Squirrels
- Carbohydrates
- Fats
- Minerals and vitamins
These components are the building blocks for our body; they help in the formation of new tissues and cells that promote growth. Many different factors have a major impact on metabolism. These include: physical activity, body type, number of calories eaten, and others.
Slowdown metabolism, the reason for this is strict diets, fasting, lack of sleep, and refusal of carbohydrates. If the body does not receive enough calories and nutrients necessary for life, then thisis regarded as starvation, and the process of saving all resources begins, fat accumulation begins. The body protects you from death, it takes care of you.
Heavy physical activity also slows down your metabolism. Well, the most interesting thing is that a sedentary lifestyle also causes the body to accumulate fat, this is also regarded by the body as a problem.
How to speed up the metabolic process? Everything requires the right approach, namely:
- Eat often and in small portions, follow a diet.
- Pay attention to sports
- Provide the body with vitamins and minerals in required quantities
- Don't skip breakfast
- Drinking enough water
As for training, strength training (bodybuilding) and cardio training (running, swimming, cycling, etc.) should prevail here. Your workouts should be hard so that you can honestly praise yourself after good exercise, but they should not be debilitating. Much does not mean good; there must be a golden mean in everything. Why shouldn't you skip breakfast? Breakfast is the most important of all meals, which starts the metabolic process, and let me also remind you that after the night the metabolism slows down, but we will speed it up by having breakfast on time. Vitamins and minerals need to be taken additionally to maintain an optimal balance in the body, again - you should not overuse fruits, they contain a lot of fructose, remember this. Eating often and in small portions speeds up your metabolism; it is optimal to eat every 2.5 - 3 hours. Well, water is an integral part of everything described above; drinking the right amount of water is important for the body and during training.
My advice: you need to learn to pay attention to every little detail. If something is not taken into account, it will affect the result in the end.
I wish you all success and patience!
Metabolism is a set of chemical transformations occurring in living organisms that ensure their growth, development, vital processes, reproduction of offspring, and active interaction with the environment.
In all living organisms, from the most primitive to the most complex, such as humans, the basis of life is metabolism and energy. Thanks to it, every organism not only maintains its existence, but develops and grows. Metabolism determines the cyclical nature of life: birth, growth and development, aging and death.
Plastic and energy metabolism
Under plastic exchange understand processes during which new compounds and new structures that are characteristic of a given organism are created in cells. Under energy metabolism understand such energy transformations, during which, as a result of biological oxidation, the energy necessary for the life of cells, tissues and the entire organism as a whole is released.
The result of biological oxidation is the formation of carbon dioxide, ammonia, phosphorus, sodium, and chlorine compounds, which are excreted from the body. This is the final stage of metabolism. It is carried out by the blood, lungs, sweat glands, and urinary organs.
Metabolism and energy is a set of chemical and physical transformations that occur in the cells and tissues of a living organism and ensure its viability. The essence of metabolism or metabolism is the sequential consumption by the body of various substances from the external environment, the assimilation, use, accumulation and loss of substances and energy throughout life, allowing the body to self-preserve, grow, develop, adapt to the environment and self-reproduce.
Metabolic processes occur in the form of successive phases: 1) extraction of energy from organic substances that enter the body with food; 2) transformation of the breakdown products of nutrients into “building blocks” for the synthesis of substances specific to the body; 3) synthesis of proteins, nucleic acids, fats, carbohydrates and other cell elements; 4) synthesis and destruction of those biologically active molecules that are necessary for the implementation of specific functions of the body.
The purpose of metabolism and energy is: firstly, to provide the plastic needs of the body, that is, to deliver to the body the chemicals necessary for the construction of its structural elements and the restoration of substances that disintegrate in the body and are lost from the body; secondly, in providing all vital functions of the body with energy.
Highlight BX(occurring at complete rest) and intermediate metabolism (the set of chemical transformations from the moment digested food substances enter the blood until the release of metabolic products from the body).
Metabolism is divided into two interconnected and simultaneously occurring processes in the cell - assimilation (anabolism) and dissimilation (catabolism). During anabolism, complex substances are biosynthesized from simpler precursor molecules. At the same time, each cell synthesizes its characteristic squirrels, fats, carbohydrates and other connections. During catabolism, large organic molecules are broken down into simple compounds with the simultaneous release of energy, which is stored mainly in the form of ATP. Catabolism refers to energy metabolism, which ensures the delivery to cells of the energy necessary for life. During life, different quantitative relationships between the processes of assimilation and dissimilation are observed: in a growing organism, assimilation predominates; from approximately the age of 22-25 to 60 years, a relative balance of anabolism and catabolism is established; after 60 years, the processes of dissimilation slightly exceed the processes of assimilation, which is accompanied by changes in the functional capabilities of various body systems.
The main stages of metabolism and their significance. The main substances necessary for the functioning of the body are squirrels, fats, carbohydrates, minerals, vitamins And water. The metabolic processes of these substances have their own characteristic features. But along with this, there are general patterns that allow us to distinguish three stages of metabolism: 1) processing of food products in the digestive organs, 2) interstitial metabolism, 3) formation of final metabolic products.
First stage- this is the sequential breakdown of the chemical components of food in the gastrointestinal tract into low-molecular structures and the absorption of the resulting simple chemical products into the blood or lymph.
The breakdown of proteins, fats and carbohydrates occurs under the influence of specific enzymes. Proteins are broken down by peptides into amino acids, fats by lipases into glycerol and fatty acids, complex carbohydrates by amylases into monosaccharides. The energy value of the first stage of metabolism is insignificant and consists mainly in the conversion of nutrients into their simplest forms, which can subsequently serve as an energy source. These forms are amino acids (about 20), three hexoses (glucose, fructose and galactose), pentose, some rarer sugars, glycerol and fatty acids. They are easily absorbed into the blood and lymph, carried by the bloodstream to the liver and peripheral tissues, where they undergo further transformations.
Second phase metabolism combines the transformation of amino acids, monosaccharides, glycerol and fatty acids. The process of interstitial metabolism leads to the formation of a few key compounds that determine the cross-talk between individual metabolic pathways, as well as between the processes of synthesis and breakdown; figuratively they are called the metabolic cauldron, or the general metabolic cauldron (Fig. 21). Such a compound, for example, is pyruvic acid, pyruvate, which plays the role of a link between carbohydrates, fats and most amino acids. Pyruvic acid is a common breakdown product of carbohydrates, fats and the nitrogen-free residue of some amino acids. Along with this, pyruvic acid can serve as a product for the synthesis of carbohydrates and fats, and also participate in the transamination of amino acids.
The main key product is acetyl coenzyme A (“active acetate”), which is formed as a result of multi-stage oxidative decarboxylation of pyruvic acid and the subsequent addition of coenzyme A. Acetyl coenzyme A is a nucleotide containing an energy-rich sulfide bond. 0H is easily subject to further oxidation, and also serves as a unifying link for the metabolism of fatty acids and some amino acids.
As a result, the metabolism of fats, proteins and carbohydrates is reduced to a common path - the tricarboxylic acid cycle (Krebs cycle), the oxidative breakdown of the final products of metabolism of carbohydrates, fats and amino acids. Thus, the processes of metabolism of carbohydrates, fats and proteins are interconnected at the stage of key metabolic products and have a common final path (Fig. 21).
| Squirrels | Carbohydrates | Fats | |||||||
| âá | âá | â | |||||||
| Amino acids | Monosaccharides | Glycerol | Fatty acid | ||||||
| â | âá | âá | |||||||
| Pyruvic acid | |||||||||
| â | |||||||||
| Acetyl coenzyme A | |||||||||
| â | |||||||||
| Tricarboxylic acid cycle | 2H | Respiratory chain | |||||||
| à | |||||||||
| ß | |||||||||
| 2H | |||||||||
| à | |||||||||
| â â | 2H | ||||||||
| H 2 O CO 2 | |||||||||
Rice. 21. Diagram of the relationship between the metabolism of carbohydrates, proteins, and fats (according to: Drzhevetskaya, 1994)
The processes of interstitial metabolism lead to the synthesis of species-specific proteins, fats and carbohydrates and their complexes - nucleoproteins, phospholipids, etc., that is, to the formation of the constituent parts of the body. Along with this, interstitial exchange processes serve as the main source of energy. The main part of the energy (2/3) is released as a result of oxidation in the Krebs cycle. During the intermediate transformations of carbohydrates, fats and proteins, the released energy is converted into the energy of special chemical compounds, the so-called macroergs, that is, compounds in which a lot of energy accumulates.
In the human body, the function of macroergs is performed by various phosphorus compounds, mainly adenosine triphosphoric acid (ATP). It is in ATP that 60-70% of all energy released during the interstitial metabolism of nutrients is accumulated. And only 30-40% of the energy released during the oxidation of proteins, fats and carbohydrates is converted into thermal energy and released from the body into the external environment in the process of heat transfer.
Third stage exchange consists in the formation and release of final products of exchange. Nitrogen-containing products are excreted in urine (mainly), feces and in small quantities through the skin. Carbon is excreted mainly in the form of CO 2 through the lungs and partly in urine and feces. Hydrogen is released primarily in the form of water through the lungs and skin, as well as in urine and feces. Mineral compounds are excreted in the same way.
Protein metabolism. The importance of proteins. Proteins or proteins are high-molecular organic compounds built from amino acid residues. Proteins occupy a leading place among organic elements, accounting for more than 50% of the dry mass of the cell. They perform the following functions:
1) plastic - the main building material of cellular structures (part of the cytoplasm, hemoglobin, and many hormones);
2) enzymatic - protein enzymes catalyze metabolic processes (respiration, digestion, excretion);
3) energy - provide the body with energy generated from the breakdown of proteins;
4) protective - blood plasma proteins provide immunity;
5) homeostatic - maintain the constancy of the body’s water-salt environment;
6) motor - the interaction of the contractile proteins actin and myosin during muscle contraction.
Proteins are the material carriers of life and form the basis of all cellular structures. Protein biosynthesis determines the growth, development and self-renewal of all structural elements in the body. The important role of proteins determines the need for their frequent renewal. The rate of protein turnover is different for different tissues. Proteins in the liver, intestinal mucosa, as well as other organs and blood plasma are renewed at the highest speed. For example, in the human liver, about 25 g of new protein is formed daily, about 20 g are replaced in the cytoplasm per day, and about 8 g are replaced in hemoglobin. Under normal conditions, up to 400 g of new protein is produced daily in the body of an adult and the same amount breaks down. Half of the protein composition of the liver is replaced by new protein within just 5-7 days. The proteins that make up the cells of the brain, heart, and gonads are renewed more slowly, and even more slowly the proteins of muscles, skin, and especially supporting tissues (tendons, bones, cartilage).
Complete and incomplete proteins. The body's protein metabolism is closely related to protein nutrition. The amino acid composition of food is of great importance for protein synthesis. All amino acids used in protein synthesis are divided into two groups: 1) non-essential, the lack of which in food can be compensated for by other amino acids, and 2) essential or vital, not formed in the body, the lack of which causes disruption of protein synthesis.
It has been established that of the 20 amino acids that make up proteins, 12 are synthesized (essential amino acids), and 8 are not synthesized (essential amino acids). Without essential amino acids, protein synthesis is dramatically disrupted: growth stops and body weight falls. Essential amino acids include valine, leucine, isoleucine, threonine, methionine, phenylalline, tryptophan, lysine. For example, the absence of the amino acid lysine in food leads to stunted growth of a child and depletion of his muscular system. Valine deficiency causes balance disorders in children.
Animal foods contain more essential amino acids than plant foods. Proteins that contain the entire required set of amino acids are called biologically complete. The highest biological value of proteins is milk, eggs, fish, and meat. Inferior proteins are proteins from corn, wheat, barley. It should be noted that two defective proteins with different amino acid compositions can jointly meet the body's needs. In this regard, the child’s food should not only contain a sufficient amount of protein, but also include proteins with high biological value, that is, of animal origin.
Stages of protein metabolism. Protein metabolism is the process of assimilation (synthesis, breakdown and excretion) of nitrogen-containing compounds (mainly proteins and amino acids) by the cells and tissues of the body.
Protein synthesis occurs from amino acids and low molecular weight polypeptides, which are formed during the breakdown of proteins in the digestive system into amino acids and are absorbed into the blood.
Enzymatic breakdown of proteins is carried out by proteinases of digestive juices - gastric, pancreatic, intestinal.
Intermediate protein metabolism. Amino acids and peptides absorbed in the intestine are transported by the blood to the liver and peripheral tissues. Here, some of them are used for the synthesis of body proteins, and some go to the formation of a number of amino acid derivatives (purine and phosphatidic bases). Finally, some amino acids undergo deamination, that is, the removal of the amino group from amino acids and their conversion into nitrogen-free products. Amino groups split off during deamination are excreted from the body in the urine in the form of ammonia and urea.
Thus, interstitial protein metabolism consists of several phases: 1) protein biosynthesis; 2) breakdown of tissue proteins, 3) conversion of amino acids. In the process of interstitial exchange of amino acids, physiologically active substances appear: hormones, nucleotides, coenzymes (Fig. 22).
As a result of interstitial protein metabolism, end products are formed (ammonia, uric acid, creatine). Urea is the main end product formed during protein metabolism. It is synthesized in the liver from ammonia released during the deamination of amino acids.
Nitrogen balance - the ratio of the amount of nitrogen entering the body with food and released from it. Since proteins contain nitrogen, the nitrogen balance can be used to judge the ratio of the amount of protein received and destroyed in the body:
Knowing how much nitrogen is absorbed, it is easy to calculate the amount of protein introduced into the body. On average, protein contains 16% nitrogen, that is, 1 g of nitrogen in 6.25 g of protein, therefore, by multiplying the amount of absorbed nitrogen by 6.25, you can determine the amount of protein introduced into the body. The amount of daily protein breakdown is determined in the same way. There is a certain relationship between the amount of nitrogen introduced with food proteins and the amount of nitrogen excreted from the body. This condition is called nitrogen balance. Consequently, in a state of nitrogen equilibrium, the breakdown of protein structures in the body is quantitatively balanced by food proteins. Nitrogen balance characterizes the normal course of protein metabolism processes in the body under conditions of sufficient protein nutrition.
| Protein food | Tissue proteins | ||||||
| â decay | â decay | ||||||
| Peptides | Peptides | ||||||
| â | â | ||||||
| Amino acids | |||||||
| neoplasm â | â interconversion | ||||||
| Substances of non-protein nature | Amino acids | ||||||
| Amino acids | NH 3 | Urea | |||||
| â | |||||||
| Tissue proteins | synthesis | decay | |||||
| Biologically active substances: hormones, nucleotides, coenzymes | decay | Metabolites of the tricarboxylic acid cycle | |||||
| â | |||||||
| CO 2 H 2 O | |||||||
Rice. 22. Ways of using amino acids in intracellular metabolism
(By: Andreeva et al., 1998)
In cases where nitrogen intake exceeds its release - positive nitrogen balance. In this case, protein synthesis prevails over its breakdown. A stable positive nitrogen balance is always observed with an increase in body weight and is noted during the period of body growth, during pregnancy due to fetal growth, during the period of recovery after serious illnesses, as well as during intense sports training, accompanied by an increase in muscle mass. In these cases, nitrogen retention occurs in the body (nitrogen retention).
Proteins are not deposited in the body, that is, they are not stored. Therefore, when a significant amount of protein is consumed with food, only part of it is spent for plastic purposes, while the majority is spent for energy purposes. In this regard, the child needs to be given the optimal amount of protein, with a set of all amino acids.
When the amount of nitrogen excreted from the body exceeds the amount taken in, it is determined as negative nitrogen balance. Negative nitrogen balance occurs when there is a complete absence or insufficient amount of protein in food, as well as when consuming food containing incomplete proteins. In all these cases, protein starvation occurs. With protein starvation, the intensity of protein synthesis and breakdown decreases.
A decrease in the activity of protein synthesis, especially functionally essential proteins, leads to disruption of the functioning of organs and systems. A growing organism especially suffers: growth is inhibited, the formation of the skeleton is disrupted, which is due to a lack of plastic material necessary for the construction of cellular structures.
Age-related features of protein metabolism. In a child’s body, processes of growth and formation of new cells and tissues occur intensively. Therefore, the need for proteins in a child is much higher than in an adult. The more intense the growth processes, the greater the need for protein.
The Institute of Nutrition of the Russian Academy of Medical Sciences has developed norms for the daily protein requirement per 1 kg of body weight for children: up to 1 year - 5-5.5 g, from 1 to 3 years - 4-4.5 g, from 4 to 7 years - 3.5-4 g, from 8 to 12 years - 3 g and over 12 years - 2-2.5 g. At these values, nitrogen is retained in the body as much as possible. Not only the quantity, but also the quality of the protein introduced is important. The completeness of proteins is determined by the presence in them of amino acids necessary for the construction of proteins in the child’s body.
With age, the need for individual essential and non-essential amino acids changes. Children of the 1st year of life need not only a much larger amount of nucleic acids, but also a qualitatively different composition of food amino acids. At the same age, the greatest retention of protein in the body is observed, as body weight rapidly increases. The greatest positive nitrogen balance is observed in the first 3 months of life.
Subsequently, the balance value, remaining positive all the time, falls and by the end of the year there are no significant changes in the nitrogen balance. So, for example, according to A.F. Tolkachevskaya (1960), nitrogen retention in children of the 1st year of life in g/kg averages: 3 months - 0.28, 3-6 months - 0.20, 6- 9 months - 0.21, 9-12 months - 0.23 (quoted from: Markosyan, 1969). The degree to which the body uses nitrogen varies individually. Both consumption and retention of dietary nitrogen depend not only on the age-related needs of the body, but also on the amount of protein introduced with food. A child, unlike an adult, has the ability to temporarily accumulate protein. The more nitrogen is introduced with food, the greater its retention in the body (Table 34).
Table 34. Nitrogen retention in preschool children with different protein content in the diet (according to: Makkhamov, 1959)
The best nitrogen retention in children from 1.6 to 3 years of age is observed with a daily dose of protein equal to 4 g per 1 kg of weight. It has been established that for children 7-8 years old, a daily dose of protein equal to 2.2-2.5 g per 1 kg of weight only maintains nitrogen balance. At a lower dose the balance is negative, and at a dose of 2.8-3 g per 1 kg of weight it becomes positive.
With age, the amount of under-oxidized products in the urine increases, the ratios between individual fractions of nitrogen and sulfur in urine change, and changes occur in the secretion of lactic acid and creatine.
The lowest content of total nitrogen in urine occurs in the first 3 months of life, and in subsequent months and up to the 1st year there is an increase in nitrogen content in urine. The daily amount of nitrogen excreted in the urine, especially during the first 4 years of life, increases rapidly. At 4-6 years of age, total urine nitrogen ranges from 98-162 mg/h. The amount of nitrogen per 1 kg of weight reaches its maximum value by 6 years, and then begins to gradually decrease.
Per 1 kg of weight, the amount of urea, gradually increasing in the 1st year of life, doubles in the 2nd year, then gradually increases again until 5-6 years, after which it begins to fall. So, for example, if a newborn excretes 0.17 g of urea per 1 kg of weight in the urine, then a 6-year-old - 0.81, and a 13-year-old - 0.64.
Thus, the period of the most intensive growth corresponds to the least release of urea. Regarding the content in the urine of children uric acid, then its excretion per 1 kg of weight during the first year of life significantly exceeds that of an adult. The uric acid content is especially high in the first 3 months, then decreases somewhat, but by the end of the year it still exceeds the adult norm by 2-4 times. The daily amount of uric acid increases fairly evenly with age and is 260 mg in the 2nd year of life, 560 mg at 10 years, 600 mg at 13 years, and 800 mg in an adult. At the same time, the relative excretion of uric acid decreases with age.
Another feature of children’s nitrogen metabolism is the constant presence of creatine in their urine. Normally, creatine is not excreted in the urine of adults, but in children, starting from the moment of birth, the excretion of creatine in the urine continues until puberty. With age, the excretion of creatine in the urine decreases significantly, the concentration of creatinine increases, and by the age of 15-16 it approaches the level of an adult.
At the age of 5-6 years, there are no gender differences in the release of both creatine and creatinine; they appear only at 10-13 years, and girls have more creatine release than boys.
In terms of creatinine excretion, sex differences appear from about 9 years of age and become more noticeable at 14-16 years of age. In boys, the daily amount of creatinine excreted in urine is much higher than in girls. These gender differences are apparently explained by the greater development of the muscular system in boys compared to girls of the same age.
