Metabolism and energy is a set of processes of transformation of substances and energy occurring in living organisms and the exchange of substances and energy between the organism and the environment. Metabolism of substances and energy is the basis of life and is one of the most important signs of living matter, distinguishing living from non-living. During the metabolic process, substances that enter the body are transformed through chemical changes into the tissue’s own substances or into final products that are excreted from the body. During these chemical transformations, energy is released and absorbed.
Metabolism or metabolism is a highly integrated and targeted process in which many enzymatic systems are involved and which is ensured by highly complex regulation at different levels.
In all organisms (and in humans as well), cellular metabolism performs 4 main specific functions.
1. Extracting energy from the environment and converting it into the energy of high-energy compounds in quantities sufficient to meet all the energy needs of the cell and the whole organism.
2. Formation from exogenous substances (or production in finished form) of intermediate compounds that are precursors of macromolecular components in the cell.
3. Synthesis of proteins, nucleic acids, carbohydrates, lipids and other cellular components from these precursors.
4. Synthesis and destruction of special biomolecules - formation and breakdown, which are associated with the performance of various specific functions of a given cell.
From the point of view of thermodynamics, living organisms are open systems, since they exchange both energy and matter with the environment, and at the same time transform both. When observed over a certain period of time, no certain changes occur in the chemical composition of the body. But this does not mean that the chemical substances that make up the body do not undergo any changes. On the contrary, they are constantly and quite intensively updated. This is because the rate of transfer of substances and energy from the environment into the body is exactly balanced by the rate of transfer from the body to the environment.
The influence of various conditions on metabolism in the human body
Metabolic intensity is assessed by total energy expenditure, and it can vary depending on many conditions, and primarily on physical work. However, even in a state of complete rest, metabolism and energy do not stop, and to ensure the continuous functioning of internal organs, maintaining muscle tone, etc., a certain amount of energy is consumed.
In young men, the basal metabolism is 1300–1600 kilocalories per day. In women, the basal metabolic rate is 6–8% lower than in men. With age (starting from 5 years), the basal metabolic rate steadily decreases. With an increase in body temperature by 1 degree, the value of basal metabolism increases by 13%. An increase in metabolic rate is also observed when the ambient temperature decreases below the comfort zone. This is an adaptation process associated with the need to maintain a constant body temperature.
The main influence on the amount of metabolism and energy is exerted by physical work. Metabolism during intense physical activity in terms of energy consumption can be 10 times higher than the main metabolism, and in very short periods (for example, short-distance swimming) even 100 times.
Intermediate metabolism in the human body
The set of chemical transformations of substances that occur in the body from the moment digested food substances enter the blood and until the final products of metabolism are released from the body is called intermediate metabolism (metabolism). Intermediate metabolism can be divided into two processes: catabolism (dissimilation) and anabolism (assimilation). Catabolism- this is the enzymatic breakdown of relatively large organic molecules, carried out in higher organisms, as a rule, by oxidation. Catabolism is accompanied by the release of energy contained in the complex structures of large organic molecules and its storage in the form of phosphate bonds of ATP. Anabolism is an enzymatic synthesis from simpler compounds of large molecular cellular components, such as polysaccharides, nucleic acids, proteins, lipids, as well as some of their precursors. Anabolic processes occur with energy consumption. Catabolism and anabolism occur in cells simultaneously and are inextricably linked with each other. Essentially, they should be considered not as two separate processes, but as two sides of one general process - metabolism, in which the transformation of substances is closely intertwined with the transformation of energy.
A more detailed examination of the metabolic pathways shows that the breakdown of basic nutrients in the cell is a series of sequential enzymatic reactions that make up the three main stages of catabolism. At the first stage, large organic molecules break down into their constituent specific structural blocks. Thus, polysaccharides break down into hexoses or pentoses, proteins into amino acids, nucleic acids into nucleotides, lipids into fatty acids, glycerol and other substances. All these reactions proceed mainly hydrolytically and the amount of energy released at this stage is very small - less than 1%. At the second stage of catabolism, even simpler molecules are formed, and the number of their types is significantly reduced. It is very important that at the second stage products are formed that are common to the metabolism of different substances. These products represent key compounds that act as key stations connecting different metabolic pathways. The products formed in the second stage of catabolism enter the third stage of catabolism, which is known as terminal oxidation. During this stage, all products are eventually oxidized to carbon monoxide and water. Almost all the energy is released in the second and third stages of catabolism.
The process of anabolism also goes through three stages. The starting materials for it are the same products that undergo transformations at the third stage of catabolism. That is, the third stage of catabolism is at the same time the first initial stage of anabolism. The reactions occurring at this stage perform a double function. On the one hand, they participate in the final stages of catabolism, and on the other hand, they also serve for anabolic processes, supplying precursor substances for subsequent stages of anabolism. At this stage, for example, protein synthesis begins.
Catabolic and anabolic reactions occur simultaneously, but in different parts of the cell. For example, the oxidation of fatty acids is carried out using a set of enzymes localized in mitochondria, while the synthesis of fatty acids is catalyzed by another enzyme system localized in the cytosol. It is due to different localization that catabolic and anabolic processes in the cell can occur simultaneously.
Regulation of metabolism and energy
Cellular metabolism is characterized by high stability and at the same time significant variability. Both of these properties ensure the constant adaptation of cells and organisms to changing environmental and internal conditions. Thus, the rate of catabolism in a cell determines the cell’s need for energy at any given moment. In the same way, the rate of biosynthesis of cellular components is determined by the needs of a given moment. The cell, for example, synthesizes amino acids at precisely the rate that is sufficient to ensure the formation of the minimum amount of protein it needs. Such economy and flexibility of metabolism is possible only if there are sufficiently subtle and sensitive mechanisms for its regulation. Metabolic regulation occurs at different levels of gradually increasing complexity.
The simplest type of regulation affects all the main parameters affecting the rate of enzymatic reactions. For example, the predominance of an acidic or alkaline environment in tissues (pH environment). The accumulation of acidic reaction products can shift the pH environment beyond the optimal state for a given enzyme and thus inhibit the process.
The next level of regulation of complex metabolic processes concerns the concentration of necessary substances in the cell. If the concentration of any necessary substance in the cell is at a sufficient level, then the synthesis of this substance stops until the moment when the concentration drops below a certain level. Thus, a certain chemical composition of the cell is maintained.
The third level of regulation is genetic control, which determines the rate of enzyme synthesis, which can vary greatly. Regulation at the gene level can lead to an increase or decrease in the concentration of certain enzymes, to a change in the types of enzymes, and induction or repression of a whole group of enzymes can occur simultaneously. Genetic regulation is highly specific, cost-effective, and provides ample opportunities for metabolic control. However, the vast majority of gene activation is a slow process. Typically, the time required for an inducer or repressor to noticeably affect enzyme concentrations is measured in hours. Therefore, this form of regulation is not suitable for urgent cases.
In higher animals and humans, there are two more levels, two mechanisms for the regulation of metabolism and energy, which differ in that they connect the metabolism occurring in different organs and tissues, and thus direct and adapt it to perform functions inherent in not individual cells, and the entire body as a whole. Such a mechanism is, first of all, the endocrine system. Hormones produced by endocrine glands serve to stimulate or suppress certain metabolic processes in other tissues or organs. For example, when the pancreas begins to produce less insulin, less glucose enters the cells, and this in turn leads to changes in a number of processes involved in metabolism.
The highest level of regulation, its most perfect form, is nervous regulation. The nervous system, in particular its central parts, performs the highest integrative functions in the body. Receiving signals from the environment and from internal organs, the central nervous system converts them and sends impulses to those organs that change the metabolic rate in which it is currently necessary to perform a certain function. Most often, the nervous system carries out its regulatory role through the endocrine glands, increasing or suppressing the flow of hormones into the blood. The influence of emotions on metabolism is well known, for example, the pre-race increase in metabolic and energy levels in athletes. In all cases, the regulating effect of the nervous system on metabolism and energy is very expedient and always aimed at the most effective adaptation of the body to changing conditions.
From the above we can conclude that in order to maintain normal metabolism in the body, a set of measures is necessary.
1. Complete daily rest
3. Balanced diet
4. Measures to cleanse the body.
Additional articles with useful information
Basic information about mineral metabolism in humansMinerals are one of the main components of food that a person needs every day. An imbalance of minerals can serve as an impetus for the development of a large number of chronic diseases.
Possible disorders in human metabolismHigh-quality daily nutrition is important for a person, but it must be taken into account that for the body it is not important what you eat, but what is important is what ultimately goes to each cell.
Organism - biological system of the biosphere
Any living creature is body, differing from inanimate nature by a set of certain properties inherent only to living matter - cellular organization and metabolism.
From a modern point of view, the body is a self-organizing energy information system that overcomes entropy (see section 9.2) by maintaining a state of unstable equilibrium.
The study of the relationship and interaction in the “organism-environment” system led to the understanding that living organisms inhabiting our planet do not exist on their own. They are completely dependent on the environment and are constantly affected by it. Each organism successfully survives and reproduces in a specific habitat characterized by a relatively narrow range of temperatures, rainfall, soil conditions, etc.
Therefore, the part of nature that surrounds living organisms and has a direct or indirect effect on them is their habitat. From it, organisms obtain everything they need for life and secrete metabolic products into it. The habitat of each organism is composed of many elements of inorganic and organic nature and elements introduced by man and his production activities. Moreover, some elements may be partially or completely indifferent to the body, others are necessary, and others have a negative effect.
Living conditions, or conditions of existence, is a set of environmental elements necessary for an organism, with which it is in inextricable unity and without which it cannot exist.
Homeostasis - self-renewal and maintaining the constancy of the internal environment of the body.
Living organisms are characterized by movement, reactivity, growth, development, reproduction and heredity, as well as adaptation. During metabolism, or metabolism, a number of chemical reactions occur in the body (for example, during respiration or photosynthesis).
Organisms such as bacteria are capable of creating organic compounds at the expense of inorganic components - nitrogen or sulfur compounds. This process is called chemosynthesis.
Metabolism in the body occurs only with the participation of special macromolecular protein substances - enzymes, acting as catalysts. Enzymes help regulate the metabolic process in the body vitamins and hormones. Together they carry out the overall chemical coordination of the metabolic process. Metabolic processes occur throughout the entire path of individual development of the organism—ontogenesis.
Ontogenesis - a set of successive morphological, physiological and biochemical transformations undergone by an organism over the entire period of life.
The organism's habitat- a set of constantly changing conditions of his life. The terrestrial biota has mastered three main habitats: , and soil, together with rocks of the near-surface part of the lithosphere.
For normal functioning, the body needs plastic and energy material. These substances enter the body with food. But only mineral salts, water and vitamins are absorbed by humans in the form in which they are found in food. Proteins, fats and carbohydrates enter the body in the form of complex complexes, and in order to be absorbed and digested, complex physical and chemical processing of food is required. In this case, food components must lose their species specificity, otherwise they will be accepted by the immune system as foreign substances. The digestive system serves these purposes.
Digestion
Digestion is a set of physical, chemical and physiological processes that ensure the processing and transformation of food products into simple chemical compounds that can be absorbed by the cells of the body. These processes occur in a certain sequence in all parts of the digestive tract (oral cavity, pharynx, esophagus, stomach, small and large intestine with the participation of the liver and gallbladder, pancreas), which is ensured by regulatory mechanisms at various levels. The sequential chain of processes leading to the breakdown of nutrients into monomers that can be absorbed is called the digestive conveyor. Depending on the origin of hydrolytic enzymes, digestion is divided into 3 types: intrinsic, symbiont and autolytic. Proper digestion is carried out by enzymes synthesized by the glands of humans or animals. Symbiont digestion occurs under the influence of enzymes synthesized by symbionts of the macroorganism (microorganisms) of the digestive tract. This is how food fiber is digested in the large intestine. Autolytic digestion is carried out under the influence of enzymes contained in the food consumed. Mother's milk contains enzymes necessary for its curdling. Depending on the location of the process of nutrient hydrolysis, intracellular and extracellular digestion are distinguished. Intracellular digestion is the process of hydrolysis of substances inside the cell by cellular (lysosomal) enzymes. Substances enter the cell by phagocytosis and pinocytosis. Intracellular digestion is characteristic of protozoa. In humans, intracellular digestion occurs in leukocytes and cells of the lymphoreticulo-histiocytic system. In higher animals and humans, digestion occurs extracellularly.
Extracellular digestion is divided into distant (cavity) and contact (parietal, or membrane). Distant (cavity) digestion is carried out with the help of enzymes of digestive secretions in the cavities of the gastrointestinal tract at a distance from the place of formation of these enzymes. Contact (parietal, or membrane) digestion (A. M. Ugolev) occurs in the small intestine in the glycocalyx zone, on the surface of microvilli with the participation of enzymes fixed on the cell membrane and ends with absorption - transport of nutrients through the enterocyte into the blood or lymph.
Kidney physiology
In the process of life activity in the human body, significant amounts of metabolic products are formed that are no longer used by cells and must be removed from the body. In addition, the body must be freed from toxic and foreign substances, from excess water, salts, and medications. Sometimes the processes of excretion are preceded by the neutralization of toxic substances, for example in the liver. Thus, substances such as phenol, indole, skatole, when combined with glucuronic and sulfuric acids, are converted into less harmful substances. Organs that perform excretory functions are called excretory or excretory. These include the kidneys, lungs, skin, liver and gastrointestinal tract. The main purpose of the excretory organs is to maintain a constant internal environment of the body. Excretory organs are functionally interconnected. A shift in the functional state of one of these organs changes the activity of the other. For example, when excess fluid is excreted through the skin at high temperatures, the volume of diuresis decreases. Violation of excretion processes inevitably leads to the appearance of pathological shifts in homeostasis, up to and including the death of the organism.
Lungs and upper respiratory tract
The lungs and upper respiratory tract remove carbon dioxide and water from the body. In addition, most aromatic substances are released through the lungs, such as ether and chloroform vapors during anesthesia, fusel oils during alcohol intoxication. When the excretory function of the kidneys is impaired, urea begins to be released through the mucous membrane of the upper respiratory tract, which decomposes, determining the corresponding odor of ammonia from the mouth. The mucous membrane of the upper respiratory tract is capable of releasing iodine from the blood.
The liver and gastrointestinal tract remove from the body with bile a number of end products of hemoglobin metabolism and other porphyrins in the form of bile pigments, and end products of cholesterol metabolism in the form of bile acids. As part of bile, medications (antibiotics), bromsulfalein, phenolrot, mannitol, inulin, etc. are also excreted from the body. The gastrointestinal tract secretes breakdown products of nutrients, water, substances received with digestive juices and bile, salts of heavy metals, some medications drugs and toxic substances (morphine, quinine, salicylates, mercury, iodine), as well as dyes used to diagnose stomach diseases (methylene blue, or congorot).
The skin carries out its excretory function due to the activity of the sweat glands and, to a lesser extent, the sebaceous glands. Sweat glands remove water, urea, uric acid, creatinine, lactic acid, alkali metal salts, especially sodium, organic matter, volatile fatty acids, trace elements, pepsinogen, amylase and alkaline phosphatase. The role of sweat glands in removing protein metabolic products increases in kidney diseases, especially in acute renal failure. With the secretion of the sebaceous glands, free fatty and unsaponifiable acids, metabolic products of sex hormones, are released from the body.
Physiology of blood
Blood, lymph, tissue, spinal, pleural, joint and other fluids form the internal environment of the body. The internal environment is distinguished by the relative constancy of its composition and physicochemical properties, which creates optimal conditions for the normal functioning of the body's cells. The concept of the constancy of the internal environment of the body was first formulated more than 100 years ago by the physiologist Claude Bernard. He came to the conclusion that “the constancy of the internal environment of the organism is a condition for independent existence,” that is, life free from sharp fluctuations in the external environment. In 1929, Walter Cannon coined the term homeostasis. Currently, homeostasis is understood as both the dynamic constancy of the internal environment of the body and the regulatory mechanisms that ensure this state. The main role in maintaining homeostasis belongs to the blood. In 1939, G. F. Lang created an idea of the blood system, in which he included peripheral blood circulating through the vessels, hematopoietic and hematopoietic organs, as well as the regulatory neurohumoral apparatus.
Metabolism and energy
In living organisms, any process is accompanied by the transfer of energy. Energy is defined as the ability to do work. A special branch of physics that studies the properties and transformations of energy in various systems is called thermodynamics. A thermodynamic system is understood as a set of objects conditionally isolated from the surrounding space.
Thermodynamic systems are divided into isolated, closed and open. Isolated systems are those whose energy and mass do not change, i.e. they do not exchange either matter or energy with the environment. Closed systems exchange energy, but not matter, with the environment, so their mass remains constant.
Open systems are systems that exchange matter and energy with the environment. From the point of view of thermodynamics, living organisms belong to open systems, since the main condition for their existence is the continuous exchange of substances and energy. The processes of life are based on the reactions of atoms and molecules, occurring in accordance with the same fundamental laws that govern the same reactions outside the body.
According to the first law of thermodynamics, energy does not disappear and does not appear again, but only passes from one form to another.
The second law of thermodynamics states that all energy eventually turns into thermal energy, and the organization of matter becomes completely disordered. In a more strict form, this law is formulated as follows: the entropy of a closed system can only increase, and the amount of useful energy (i.e., that with the help of which work can be done) inside the system can only decrease. Entropy refers to the degree of disorder of a system.
The inevitable tendency to increase entropy, accompanied by the equally inevitable transformation of useful chemical energy into useless thermal energy, forces living systems to capture more and more portions of energy (food) in order to maintain their structural and functional state. In fact, the ability to extract useful energy from the environment is one of the main properties that distinguish living systems from non-living ones, i.e. the continuous metabolism of matter and energy is one of the main characteristics of living beings. To counteract the increase in entropy and maintain their structure and functions, living beings must receive energy in a form accessible to them from the environment and return an equivalent amount of energy to the environment in a form less suitable for further use.
Metabolism and energy is a set of physical, chemical and physiological processes of transformation of substances and energy in living organisms, as well as the exchange of substances and energy between the body and the environment. Metabolism in living organisms consists of the intake of various substances from the external environment, their transformation and use in vital processes and the release of the resulting decay products into the environment.
All transformations of matter and energy occurring in the body are united by a common name - metabolism (metabolism). At the cellular level, these transformations occur through complex sequences of reactions called metabolic pathways and can involve thousands of different reactions. These reactions do not occur chaotically, but in a strictly defined sequence and are regulated by many genetic and chemical mechanisms. Metabolism can be divided into two interrelated but multidirectional processes: anabolism (assimilation) and catabolism (dissimilation).
Anabolism is a set of processes of biosynthesis of organic substances (cell components and other structures of organs and tissues). It ensures growth, development, renewal of biological structures, as well as energy accumulation (synthesis of macroergs). Anabolism consists of the chemical modification and rearrangement of molecules supplied by food into other more complex biological molecules. For example, the inclusion of amino acids in proteins synthesized by a cell in accordance with the instructions contained in the genetic material of a given cell.
Catabolism is a set of processes of breaking down complex molecules into simpler substances, using some of them as substrates for biosynthesis and breaking down the other part into final metabolic products with the formation of energy. End products of metabolism include water (about 350 ml per day in humans), carbon dioxide (about 230 ml/min), carbon monoxide (0.007 ml/min), urea (about 30 g/day), as well as other substances containing nitrogen (about 6 g/day).
Catabolism extracts chemical energy from the molecules contained in food and uses this energy to provide necessary functions. For example, the formation of free amino acids as a result of the breakdown of proteins supplied with food and the subsequent oxidation of these amino acids in the cell with the formation of CO2 and H2O, which is accompanied by the release of energy.
The processes of anabolism and catabolism are in a state of dynamic equilibrium in the body. The predominance of anabolic processes over catabolic ones leads to growth and accumulation of tissue mass, and the predominance of catabolic processes leads to partial destruction of tissue structures. The state of equilibrium or nonequilibrium ratio of anabolism and catabolism depends on age (anabolism predominates in childhood, balance is usually observed in adults, catabolism predominates in old age), health status, physical or psycho-emotional stress performed by the body.