Oxygen is actively used for respiration. And this is its main function. It is also necessary for other processes that normalize the activity of the whole organism as a whole.

What is oxygen for?

Oxygen is the guarantee successful implementation a number of functions, including:
- increase mental performance;
- increasing the body's resistance to stress and reducing nervous stress;
- maintaining a normal level of oxygen in the blood, thereby improving the nutrition of skin cells and organs;
- work is normalized internal organs, accelerates metabolism;
- increased immunity;
- weight loss - oxygen contributes to the active breakdown of fats;
- normalization of sleep - due to the saturation of cells with oxygen, the body relaxes, sleep becomes deeper and lasts longer;
- Solving the problem of hypoxia (ie lack of oxygen).

Natural oxygen, according to scientists and physicians, is quite capable of coping with these tasks, but, unfortunately, in a city with enough oxygen, problems arise.

Scientists say that the amount of oxygen necessary to ensure normal life can be found only in forest park areas, where its level is about 21%, suburban forests - about 22%. Other areas include seas and oceans. Plus, exhaust gases also play a role in the city. Due to the lack of the proper amount of oxygen, people experience a permanent state of hypoxia, i.e. lack of oxygen. As a result, many note a significant deterioration in health.

Scientists have determined that 200 years ago a person received up to 40% of natural oxygen from the air, and today this figure has decreased by 2 times - up to 21%.

How to replace natural oxygen

Since natural oxygen is clearly not enough for a person, doctors recommend adding special oxygen therapy. There are no contraindications for such a procedure, but there will be benefits for sure. Among the sources of obtaining additional oxygen include oxygen cylinders and pillows, concentrators, cocktails, oxygen-forming cocktails.

In addition, in order to receive the maximum possible amount of natural oxygen, you need to breathe properly. Usually people breastfeed, but this method is wrong and unnatural for a person. This is due to the fact that when inhaled by the chest, the air cannot completely fill the lungs to clear them. Doctors say that chest breathing provokes incorrect work nervous system. Hence stress, depression and other types of disorders. To feel good and get as much oxygen from the air as possible, you need to breathe with your stomach.

You probably know that breathing is necessary so that the oxygen necessary for life enters the body with inhaled air, and when exhaling, the body releases carbon dioxide to the outside.

All living things breathe - and animals,

both birds and plants.

And why do living organisms need oxygen so much that life is impossible without it? And where does carbon dioxide come from in the cells, from which the body needs to constantly be released?

The fact is that each cell of a living organism is a small but very active biochemical production. And you know that no production is possible without energy. All processes that take place in cells and tissues proceed with the consumption of a large amount of energy.

Where does it come from?

With the food we eat - from carbohydrates, fats and proteins. In cells, these substances are oxidized. Most often, the chain of transformations of complex substances leads to the formation of a universal energy source - glucose. As a result of the oxidation of glucose, energy is released. This is where oxygen is needed for oxidation. The energy that is released as a result of these reactions, the cell stores in the form of special high-energy molecules - they, like batteries, or accumulators, give energy as needed. And the end product of the oxidation of nutrients is water and carbon dioxide, which are removed from the body: from the cells it enters the blood, which carries carbon dioxide to the lungs, and there it is excreted during exhalation. In one hour, a person releases from 5 to 18 liters of carbon dioxide and up to 50 grams of water through the lungs.

By the way...

High-energy molecules that are "fuel" for biochemical processes are called ATP - adenosine triphosphoric acid. In humans, the lifespan of one ATP molecule is less than 1 minute. The human body synthesizes about 40 kg of ATP per day, but at the same time all of it is spent almost immediately, and there is practically no ATP reserve in the body. For normal life, it is necessary to constantly synthesize new ATP molecules. That is why, without oxygen, a living organism can live for a maximum of a few minutes.

Are there living organisms that do not need oxygen?

Each of us is familiar with the processes of anaerobic respiration! So, the fermentation of dough or kvass is an example of an anaerobic process carried out by yeast: they oxidize glucose to ethanol (alcohol); the process of souring milk is the result of the work of lactic acid bacteria that carry out lactic acid fermentation - they convert the milk sugar lactose into lactic acid.

Why do we need oxygen breathing, if there is oxygen-free?

Then, that aerobic oxidation is many times more efficient than anaerobic. Compare: in the process of anaerobic breakdown of one glucose molecule, only 2 ATP molecules are formed, and as a result of the aerobic breakdown of a glucose molecule, 38 ATP molecules are formed! For complex organisms with a high rate and intensity of metabolic processes, anaerobic respiration is simply not enough to sustain life - so an electronic toy that requires 3-4 batteries to work simply will not turn on if only one battery is inserted into it.

Is oxygen-free respiration possible in the cells of the human body?

Certainly! The first step in the breakdown of the glucose molecule, called glycolysis, takes place without the presence of oxygen. Glycolysis is a process common to almost all living organisms. Glycolysis produces pyruvic acid (pyruvate). It is she who sets off on the path of further transformations, leading to the synthesis of ATP both with oxygen and oxygen-free respiration.

So, in muscles, ATP reserves are very small - they are only enough for 1-2 seconds of muscle work. If a muscle needs short-term, but vigorous activity, anaerobic respiration is the first to be mobilized in it - it is activated faster and provides energy for about 90 seconds of active muscle work. If the muscle is actively working for more than two minutes, then aerobic respiration is connected: with it, ATP production occurs slowly, but it gives enough energy to maintain physical activity for a long time (up to several hours).

Oxygen- one of the most common elements not only in nature, but also in the composition of the human body.

The special properties of oxygen as a chemical element have made it a necessary partner in the fundamental processes of life during the evolution of living beings. The electronic configuration of the oxygen molecule is such that it has unpaired electrons that are highly reactive. Possessing therefore high oxidizing properties, the oxygen molecule is used in biological systems as a kind of trap for electrons, the energy of which is extinguished when they are associated with oxygen in the water molecule.

There is no doubt that oxygen "came to the yard" for biological processes as an electron acceptor. Very useful for an organism whose cells (especially biological membranes) are built from a material that is physically and chemically diverse is the solubility of oxygen in both the aqueous and lipid phases. This makes it relatively easy for it to diffuse to any structural formations of cells and participate in oxidative reactions. True, oxygen is soluble in fats several times better than in the aquatic environment, and this is taken into account when oxygen is used as a therapeutic agent.

Every cell in our body requires an uninterrupted supply of oxygen, where it is used in various metabolic reactions. In order to deliver and sort it into cells, you need a fairly powerful transport apparatus.

In a normal state, the cells of the body need to supply about 200-250 ml of oxygen every minute. It is easy to calculate that the need for it per day is a considerable amount (about 300 liters). With hard work, this need increases tenfold.

Diffusion of oxygen from the pulmonary alveoli into the blood occurs due to the alveolar-capillary difference (gradient) of oxygen tension, which, when breathing with ordinary air, is: 104 (pO 2 in the alveoli) - 45 (pO 2 in the pulmonary capillaries) \u003d 59 mm Hg. Art.

Alveolar air (with an average lung capacity of 6 liters) contains no more than 850 ml of oxygen, and this alveolar reserve can provide the body with oxygen for only 4 minutes, given that the body's average oxygen demand in a normal state is approximately 200 ml per minute.

It has been calculated that if molecular oxygen simply dissolves in blood plasma (and it dissolves poorly in it - 0.3 ml per 100 ml of blood), then in order to ensure the normal need for cells in it, it is necessary to increase the rate of vascular blood flow to 180 l in a minute. In fact, blood moves at a speed of only 5 liters per minute. Delivery of oxygen to tissues is carried out due to a wonderful substance - hemoglobin.

Hemoglobin contains 96% protein (globin) and 4% non-protein component (heme). Hemoglobin, like an octopus, captures oxygen with its four tentacles. The role of "tentacles", specifically grasping oxygen molecules in the arterial blood of the lungs, is performed by heme, or rather, the atom of ferrous iron located in its center. Iron is "fixed" within the porphyrin ring with the help of four bonds. Such a complex of iron with porphyrin is called protoheme or simply heme. The other two iron bonds are directed perpendicular to the plane of the porphyrin ring. One of them goes to the protein subunit (globin), and the other is free, it is she who directly catches molecular oxygen.

Hemoglobin polypeptide chains are arranged in space in such a way that their configuration is close to spherical. Each of the four globules has a "pocket" in which heme is placed. Each heme is able to capture one oxygen molecule. A hemoglobin molecule can bind a maximum of four oxygen molecules.

How does hemoglobin work?

Observations of the respiratory cycle of the “molecular lung” (as the well-known English scientist M. Perutz called hemoglobin) reveals the amazing features of this pigment protein. It turns out that all four gems work in concert, and not autonomously. Each of the gems is, as it were, informed about whether its partner has added oxygen or not. In deoxyhemoglobin, all the "tentacles" (iron atoms) protrude from the plane of the porphyrin ring and are ready to bind the oxygen molecule. Catching an oxygen molecule, iron is drawn into the porphyrin ring. The first oxygen molecule is the most difficult to attach, and each subsequent one is better and easier. In other words, hemoglobin acts according to the proverb "appetite comes with eating." The addition of oxygen even changes the properties of hemoglobin: it becomes a stronger acid. This fact has great importance in the transport of oxygen and carbon dioxide.

Saturated with oxygen in the lungs, hemoglobin in the composition of red blood cells carries it with the blood flow to the cells and tissues of the body. However, before saturating hemoglobin, oxygen must be dissolved in the blood plasma and pass through the erythrocyte membrane. In practice, especially when using oxygen therapy, it is important for a doctor to take into account the potential of erythrocyte hemoglobin to retain and deliver oxygen.

One gram of hemoglobin under normal conditions can bind 1.34 ml of oxygen. Reasoning further, it can be calculated that with an average hemoglobin content in the blood of 14-16 ml%, 100 ml of blood binds 18-21 ml of oxygen. If we take into account the volume of blood, which averages about 4.5 liters in men, and 4 liters in women, then the maximum binding activity of erythrocyte hemoglobin is about 750-900 ml of oxygen. Of course, this is only possible if all hemoglobin is saturated with oxygen.

When breathing atmospheric air, hemoglobin is saturated incompletely - by 95-97%. You can saturate it by using pure oxygen for breathing. It is enough to increase its content in the inhaled air to 35% (instead of the usual 24%). In this case, the oxygen capacity will be maximum (equal to 21 ml of O 2 per 100 ml of blood). No more oxygen can bind due to the lack of free hemoglobin.

Not a large number of oxygen remains dissolved in the blood (0.3 ml per 100 ml of blood) and is transported in this form to the tissues. Under natural conditions, the needs of tissues are satisfied at the expense of oxygen associated with hemoglobin, because oxygen dissolved in plasma is negligible - only 0.3 ml per 100 ml of blood. Hence the conclusion follows: if the body needs oxygen, then it cannot live without hemoglobin.

During the lifetime (it is approximately 120 days), the erythrocyte does a gigantic job, transferring about a billion oxygen molecules from the lungs to the tissues. However, hemoglobin has interesting feature: it does not always add oxygen with the same greed, nor does it give it to the surrounding cells with the same willingness. This behavior of hemoglobin is determined by its spatial structure and can be controlled by both internal and external factors.

The process of saturation of hemoglobin with oxygen in the lungs (or dissociation of hemoglobin in cells) is described by a curve that has an S-shape. Thanks to this dependence, a normal supply of oxygen to cells is possible even with small drops in it in the blood (from 98 to 40 mm Hg).

The position of the S-shaped curve is not constant, and its change indicates important changes in the biological properties of hemoglobin. If the curve shifts to the left and its bend decreases, then this indicates an increase in the affinity of hemoglobin for oxygen, a decrease in the reverse process - the dissociation of oxyhemoglobin. On the contrary, a shift of this curve to the right (and an increase in the bend) indicates the opposite picture - a decrease in the affinity of hemoglobin for oxygen and a better return to its tissues. It is clear that the shift of the curve to the left is appropriate for the capture of oxygen in the lungs, and to the right - for its release in the tissues.

The dissociation curve of oxyhemoglobin varies depending on the pH of the medium and temperature. The lower the pH (shift to the acidic side) and the higher the temperature, the worse oxygen is captured by hemoglobin, but the better it is given to tissues during the dissociation of oxyhemoglobin. Hence the conclusion: in a hot atmosphere, oxygen saturation of the blood is inefficient, but with an increase in body temperature, the unloading of oxyhemoglobin from oxygen is very active.

Erythrocytes also have their own regulatory device. It is 2,3-diphosphoglyceric acid, which is formed during the breakdown of glucose. The "mood" of hemoglobin in relation to oxygen also depends on this substance. When 2,3-diphosphoglyceric acid accumulates in red blood cells, it reduces the affinity of hemoglobin for oxygen and promotes its return to tissues. If it is not enough - the picture is reversed.

Interesting events also occur in the capillaries. In the arterial end of the capillary, oxygen diffuses perpendicular to the movement of blood (from the blood into the cell). The movement occurs in the direction of the difference in partial pressures of oxygen, i.e., into the cells.

The preference of the cell is given to physically dissolved oxygen, and it is used in the first place. At the same time, oxyhemoglobin is also unloaded from its burden. The more intensively the body works, the more it requires oxygen. When oxygen is released, the tentacles of hemoglobin are released. Due to the absorption of oxygen by tissues, the content of oxyhemoglobin in venous blood drops from 97 to 65-75%.

Unloading oxyhemoglobin along the way contributes to the transport of carbon dioxide. The latter, being formed in the tissues as the end product of the combustion of carbon-containing substances, enters the bloodstream and can cause a significant decrease in the pH of the environment (acidification), which is incompatible with life. In fact, the pH of arterial and venous blood can fluctuate in an extremely narrow range (no more than 0.1), and for this it is necessary to neutralize carbon dioxide and take it out of the tissues into the lungs.

Interestingly, the accumulation of carbon dioxide in the capillaries and a slight decrease in the pH of the medium just contribute to the release of oxygen by oxyhemoglobin (the dissociation curve shifts to the right, and the S-shaped bend increases). Hemoglobin, which plays the role of the buffer system of the blood itself, neutralizes carbon dioxide. This produces bicarbonates. Part of the carbon dioxide is bound by hemoglobin itself (as a result, carbhemoglobin is formed). It is estimated that hemoglobin is directly or indirectly involved in the transport of up to 90% of carbon dioxide from tissues to the lungs. In the lungs, reverse processes occur, because the oxygenation of hemoglobin leads to an increase in its acidic properties and return to environment hydrogen ions. The latter, combining with bicarbonates, form carbonic acid, which is split by the enzyme carbonic anhydrase into carbon dioxide and water. Carbon dioxide is released by the lungs, and oxyhemoglobin, binding cations (in exchange for the split off hydrogen ions), moves to the capillaries of peripheral tissues. Such a close relationship between the acts of supplying tissues with oxygen and the removal of carbon dioxide from tissues to the lungs reminds us that when oxygen is used for therapeutic purposes, one should not forget about another function of hemoglobin - to free the body from excess carbon dioxide.

The arterial-venous difference or oxygen pressure difference along the capillary (from the arterial to the venous end) gives an idea of ​​the oxygen demand of the tissues. The length of the capillary run of oxyhemoglobin varies in different organs (and their oxygen needs are not the same). Therefore, for example, the oxygen tension in the brain drops less than in the myocardium.

Here, however, it is necessary to make a reservation and recall that the myocardium and other muscle tissues are in special conditions. Muscle cells have an active system for capturing oxygen from the flowing blood. This function is performed by myoglobin, which has the same structure and works on the same principle as hemoglobin. Only myoglobin has one protein chain (and not four, like hemoglobin) and, accordingly, one heme. Myoglobin is like a quarter of hemoglobin and captures only one molecule of oxygen.

The peculiarity of the structure of myoglobin, which is limited only by the tertiary level of organization of its protein molecule, is associated with interaction with oxygen. Myoglobin binds oxygen five times faster than hemoglobin (it has a high affinity for oxygen). The curve of saturation of myoglobin (or dissociation of oxymyoglobin) with oxygen has the form of a hyperbola, and not an S-shape. This makes great biological sense, since myoglobin, which is located deep in the muscle tissue (where the partial pressure of oxygen is low), greedily grabs oxygen even under conditions of low tension. An oxygen reserve is created, as it were, which is spent, if necessary, on the formation of energy in mitochondria. For example, in the heart muscle, where there is a lot of myoglobin, during the period of diastole, a reserve of oxygen is formed in the cells in the form of oxymyoglobin, which during systole satisfies the needs of muscle tissue.

Apparently, the constant mechanical work of the muscular organs required additional devices for catching and reserving oxygen. Nature created it in the form of myoglobin. It is possible that in non-muscle cells there is some as yet unknown mechanism for capturing oxygen from the blood.

In general, the usefulness of the work of erythrocyte hemoglobin is determined by how much it was able to convey to the cell and transfer oxygen molecules to it and take out carbon dioxide accumulating in tissue capillaries. Unfortunately, this worker sometimes does not work at full strength and through no fault of his own: the release of oxygen from oxyhemoglobin in the capillary depends on the ability of biochemical reactions in cells to consume oxygen. If little oxygen is consumed, then it seems to “stagnate” and, due to its low solubility in a liquid medium, no longer comes from the arterial bed. At the same time, doctors observe a decrease in the arteriovenous oxygen difference. It turns out that hemoglobin uselessly carries part of the oxygen, and besides, it takes out less carbon dioxide. The situation is not pleasant.

Knowledge of the laws of operation of the oxygen transport system in natural conditions allows the doctor to draw a number of useful conclusions for the correct use of oxygen therapy. It goes without saying that it is necessary to use, together with oxygen, agents that stimulate erythropoiesis, increase blood flow in the affected organism and help the use of oxygen in the tissues of the body.

At the same time, it is necessary to clearly know for what purposes oxygen is consumed in cells, ensuring their normal existence?

On its way to the site of participation in metabolic reactions inside cells, oxygen overcomes many structural formations. The most important of them are biological membranes.

Any cell has a plasma (or outer) membrane and a bizarre variety of other membrane structures that limit subcellular particles (organelles). Membranes are not just partitions, but formations that perform special functions (transport, decomposition and synthesis of substances, energy generation, etc.), which are determined by their organization and the composition of their biomolecules. Despite the variability in the shapes and sizes of membranes, they consist mainly of proteins and lipids. The remaining substances, also found in membranes (for example, carbohydrates), are connected by chemical bonds to either lipids or proteins.

We will not dwell on the details of the organization of protein-lipid molecules in membranes. It is important to note that all models of the structure of biomembranes (“sandwich”, “mosaic”, etc.) suggest the presence in the membranes of a bimolecular lipid film held together by protein molecules.

The lipid layer of the membrane is a liquid film that is in constant motion. Oxygen, due to its good solubility in fats, passes through the double lipid layer of membranes and enters the cells. Part of the oxygen is transferred to the internal environment of cells through carriers such as myoglobin. It is believed that oxygen is in a soluble state in the cell. Probably, it dissolves more in lipid formations, and less in hydrophilic formations. Recall that the structure of oxygen perfectly meets the criteria for an oxidizing agent used as an electron trap. It is known that the main concentration of oxidative reactions occurs in special organelles - mitochondria. The figurative comparisons that biochemists endowed mitochondria indicate the purpose of these small (0.5 to 2 micron in size) particles. They are called both "energy stations" and "power stations" of the cell, thus emphasizing their leading role in the formation of energy-rich compounds.

Here, perhaps, it is worth making a small digression. As you know, one of the fundamental features of living things is efficient extraction energy. The human body uses external sources of energy - nutrients(carbohydrates, lipids and proteins), which are broken down into smaller pieces (monomers) with the help of hydrolytic enzymes of the gastrointestinal tract. The latter are absorbed and delivered to the cells. Energy value are only those substances that contain hydrogen, which has a large supply of free energy. The main task of the cell, or rather the enzymes contained in it, is to process substrates in such a way as to tear hydrogen from them.

Almost all enzyme systems that perform a similar role are localized in mitochondria. Here, a fragment of glucose (pyruvic acid), fatty acids and carbon skeletons of amino acids are oxidized. After the final treatment, the remaining hydrogen is “ripped off” from these substances.

Hydrogen, which is detached from combustible substances with the help of special enzymes (dehydrogenases), is not in a free form, but in connection with special carriers - coenzymes. They are nicotinamide (vitamin PP) derivatives - NAD (nicotinamide adenine dinucleotide), NADP (nicotinamide adenine dinucleotide phosphate) and riboflavin (vitamin B 2) derivatives - FMN (flavin mononucleotide) and FAD (flavin adenine dinucleotide).

Hydrogen does not burn immediately, but gradually, in portions. Otherwise, the cell could not use its energy, because the interaction of hydrogen with oxygen would cause an explosion, which is easily demonstrated in laboratory experiments. In order for hydrogen to give up the energy stored in it in parts, there is a chain of electron and proton carriers in the inner membrane of mitochondria, otherwise called the respiratory chain. At a certain section of this chain, the paths of electrons and protons diverge; electrons jump through cytochromes (consisting, like hemoglobin, of protein and heme), and protons go out into the environment. At the end point of the respiratory chain, where cytochrome oxidase is located, electrons “slip” onto oxygen. In this case, the energy of electrons is completely extinguished, and oxygen, binding protons, is reduced to a water molecule. Water energy value for the body no longer represents.

The energy given off by electrons jumping along the respiratory chain is converted into the energy of chemical bonds of adenosine triphosphate - ATP, which serves as the main energy accumulator in living organisms. Since two acts are combined here: oxidation and the formation of energy-rich phosphate bonds (available in ATP), the process of energy generation in the respiratory chain is called oxidative phosphorylation.

How does the combination of the movement of electrons along the respiratory chain and the capture of energy during this movement take place? It's not entirely clear yet. Meanwhile, the action of biological energy converters would solve many issues related to the salvation of the cells of the body affected by the pathological process, as a rule, experiencing energy hunger. According to experts, the disclosure of the secrets of the mechanism of energy generation in living beings will lead to the creation of technically more promising energy generators.

These are perspectives. So far, it is known that the capture of electron energy occurs in three sections of the respiratory chain and, consequently, the combustion of two hydrogen atoms produces three ATP molecules. The efficiency of such an energy transformer approaches 50%. Given that the share of energy supplied to the cell during the oxidation of hydrogen in the respiratory chain is at least 70-90%, colorful comparisons that were awarded to mitochondria become understandable.

ATP energy is used in a variety of processes: to assemble complex structures (for example, proteins, fats, carbohydrates, nucleic acids) from building proteins, perform mechanical activity (muscle contraction), electrical work (appearance and propagation of nerve impulses), transport and accumulation of substances inside cells, etc. In short, life without energy is impossible, and as soon as there is a sharp shortage of it, living beings die.

Let us return to the question of the place of oxygen in energy generation. At first glance, the direct participation of oxygen in this vital process seems disguised. It would probably be appropriate to compare the combustion of hydrogen (and the generation of energy along the way) with a production line, although the respiratory chain is a line not for assembling, but for “disassembling” a substance.

Hydrogen is at the origin of the respiratory chain. From it, a stream of electrons rushes to the final point - oxygen. In the absence of oxygen or its shortage, the production line either stops or does not operate at full load, because there is no one to unload it, or the unloading efficiency is limited. No flow of electrons - no energy. According to the apt definition of the outstanding biochemist A. Szent-Gyorgyi, life is controlled by the flow of electrons, the movement of which is set by an external source of energy - the Sun. It is tempting to continue this thought and add that since life is controlled by the flow of electrons, then oxygen maintains the continuity of such a flow.

Is it possible to replace oxygen with another electron acceptor, unload the respiratory chain and restore energy production? In principle, it is possible. This is easily demonstrated in laboratory experiments. For the body to choose such an electron acceptor as oxygen, so that it is easily transported, penetrates into all cells and participates in redox reactions, is still an incomprehensible task.

So, oxygen, while maintaining the continuity of the flow of electrons in the respiratory chain, under normal conditions contributes to the constant formation of energy from substances entering the mitochondria.

Of course, the situation presented above is somewhat simplified, and we did this in order to more clearly show the role of oxygen in the regulation of energy processes. The effectiveness of such regulation is determined by the operation of the apparatus for transforming the energy of moving electrons (electric current) into the chemical energy of ATP bonds. If the nutrients even in the presence of oxygen. burn in the mitochondria "for nothing", released at the same time thermal energy is useless for the body, and energy starvation may occur with all the ensuing consequences. However, such extreme cases of impaired phosphorylation during electron transfer in tissue mitochondria are hardly possible and have not been encountered in practice.

Much more frequent are cases of dysregulation of energy production associated with insufficient oxygen supply to cells. Does this mean immediate death? It turns out not. Evolution disposed wisely, leaving a certain margin of energy strength to human tissues. It is provided by an oxygen-free (anaerobic) pathway for the formation of energy from carbohydrates. Its efficiency, however, is relatively low, since the oxidation of the same nutrients in the presence of oxygen provides 15-18 times more energy than without it. However, in critical situations, the tissues of the body remain viable precisely due to the anaerobic energy generation (through glycolysis and glycogenolysis).

This small digression, telling about the potential for the formation of energy and the existence of an organism without oxygen, is another evidence that oxygen is the most important regulator of life processes and that existence is impossible without it.

However, no less important is the participation of oxygen not only in energy, but also in plastic processes. As far back as 1897, our outstanding compatriot A. N. Bach and the German scientist K. Engler, who developed the position “on the slow oxidation of substances by activated oxygen,” pointed to this side of oxygen. For a long time, these provisions remained in oblivion due to too much interest of researchers in the problem of the participation of oxygen in energy reactions. It was only in the 1960s that the question of the role of oxygen in the oxidation of many natural and foreign compounds was again raised. As it turned out, this process has nothing to do with the formation of energy.

The main organ that uses oxygen to introduce it into the molecule of the oxidized substance is the liver. In liver cells, many foreign compounds are neutralized in this way. And if the liver is rightly called a laboratory for the neutralization of drugs and poisons, then oxygen in this process is given a very honorable (if not dominant) place.

Briefly about the localization and arrangement of the oxygen consumption apparatus for plastic purposes. In the membranes of the endoplasmic reticulum, penetrating the cytoplasm of liver cells, there is a short chain of electron transport. It differs from a long (with a large number of carriers) respiratory chain. The source of electrons and protons in this chain is reduced NADP, which is formed in the cytoplasm, for example, during the oxidation of glucose in the pentose phosphate cycle (hence, glucose can be called a full partner in the detoxification of substances). Electrons and protons are transferred to a special protein containing flavin (FAD) and from it to the final link - a special cytochrome called cytochrome P-450. Like hemoglobin and mitochondrial cytochromes, it is a heme-containing protein. Its function is dual: it binds the oxidized substance and participates in the activation of oxygen. The end result of such a complex function of cytochrome P-450 is expressed in the fact that one oxygen atom enters the molecule of the oxidized substance, the second - into the water molecule. The differences between the final acts of oxygen consumption during the formation of energy in mitochondria and during the oxidation of substances of the endoplasmic reticulum are obvious. In the first case, oxygen is used for the formation of water, and in the second case, for the formation of both water and an oxidized substrate. The proportion of oxygen consumed in the body for plastic purposes can be 10-30% (depending on the conditions for the favorable course of these reactions).

Raising the question (even purely theoretically) about the possibility of replacing oxygen with other elements is meaningless. Considering that this pathway of oxygen utilization is also necessary for the exchange of the most important natural compounds - cholesterol, bile acids, steroid hormones - it is easy to understand how far the functions of oxygen extend. It turns out that it regulates the formation of a number of important endogenous compounds and the detoxification of foreign substances (or, as they are now called, xenobiotics).

However, it should be noted that the enzymatic system of the endoplasmic reticulum, which uses oxygen to oxidize xenobiotics, has some costs, which are as follows. Sometimes, when oxygen is introduced into a substance, a more toxic compound is formed than the original one. In such cases, oxygen acts as if an accomplice in poisoning the body with harmless compounds. Such costs take a serious turn, for example, when carcinogens are formed from procarcinogens with the participation of oxygen. In particular, the well-known component of tobacco smoke, benzpyrene, which was considered a carcinogen, actually acquires these properties when oxidized in the body to form oxybenzopyrene.

These facts make us pay close attention to those enzymatic processes in which oxygen is used as a building material. In some cases, it is necessary to develop preventive measures against this method of oxygen consumption. This task is very difficult, but it is necessary to look for approaches to it, so that with the help of various tricks direct the regulating potencies of oxygen in the right direction for the body.

The latter is especially important when oxygen is used in such an "uncontrolled" process as the peroxide (or free radical) oxidation of unsaturated fatty acids. Unsaturated fatty acids are part of various lipids in biological membranes. The architectonics of membranes, their permeability, and the functions of the enzymatic proteins that make up the membranes are largely determined by the ratio of various lipids. Lipid peroxidation occurs either with the help of enzymes or without them. The second option does not differ from free radical lipid oxidation in conventional chemical systems and requires the presence of ascorbic acid. The participation of oxygen in lipid peroxidation is, of course, not the best way to apply its valuable biological properties. The free radical nature of this process, which can be initiated by ferrous iron (the center of radical formation), allows in a short time to lead to the breakdown of the lipid backbone of the membranes and, consequently, to cell death.

Such a catastrophe in natural conditions, however, does not occur. Cells contain natural antioxidants (vitamin E, selenium, some hormones) that break the chain of lipid peroxidation, preventing the formation of free radicals. Nevertheless, the use of oxygen in lipid peroxidation, according to some researchers, has positive sides. Under biological conditions, lipid peroxidation is necessary for membrane self-renewal, since lipid peroxides are more water-soluble compounds and are more easily released from the membrane. They are replaced by new, hydrophobic lipid molecules. Only the excess of this process leads to the collapse of the membranes and pathological changes in the body.

It's time to take stock. So, oxygen is the most important regulator of vital processes, used by the cells of the body as a necessary component for the formation of energy in the respiratory chain of mitochondria. The oxygen requirements of these processes are provided differently and depend on many conditions (on the power of the enzymatic system, the abundance in the substrate and the availability of oxygen itself), but still the lion's share of oxygen is spent on energy processes. Hence, the “living wage” and the functions of individual tissues and organs in case of an acute lack of oxygen are determined by the endogenous oxygen reserves and the power of the oxygen-free pathway of energy generation.

However, it is equally important to supply oxygen to other plastic processes, although this consumes a smaller part of it. In addition to a number of necessary natural syntheses (cholesterol, bile acids, prostaglandins, steroid hormones, biologically active products of amino acid metabolism), the presence of oxygen is especially necessary for the neutralization of drugs and poisons. In case of poisoning with foreign substances, one can perhaps assume that oxygen is of greater vital importance for plastic than for energy purposes. With intoxication, this side of the action just finds practical application. And only in one case the doctor has to think about how to put a barrier on the way of oxygen consumption in the cells. We are talking about the inhibition of the use of oxygen in the peroxidation of lipids.

As we can see, knowledge of the features of delivery and consumption of oxygen in the body is the key to unraveling the disorders that occur during various kinds of hypoxic conditions, and to the correct tactics. therapeutic use oxygen in the clinic.

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Everything about everything. Volume 5 Likum Arkady

Why do we need oxygen?

Why do we need oxygen?

Animals can go without food for several weeks, without water for several days. But without oxygen, they die after a few minutes. Oxygen is chemical element, and one of the most common on earth. It is all around us, making up about one-fifth of the air (and almost everything else is nitrogen). Oxygen combines with almost all other elements. In living organisms, it combines with hydrogen, carbon and other substances, making up about two-thirds of the total weight in the human body.

At normal temperatures, oxygen reacts with other elements very slowly, forming new substances called oxides. This process is called an oxidation reaction. Oxidation occurs all the time in living organisms. Food is the fuel of living cells.

When food is oxidized, energy is released that the body uses for movement and for its own growth. The slow oxidation that occurs in the organisms of living beings is often called internal respiration. A person breathes in oxygen through the lungs. From the lungs, it enters the circulatory system and is carried by it throughout the body. By breathing air, we supply the cells of our body with oxygen for their internal respiration. Thus, we need oxygen to obtain energy, thanks to which the body can function.

People with respiratory problems are often placed in oxygen chambers, where the patient breathes air, forty to sixty percent oxygen, and does not have to expend much energy to obtain the amount of oxygen he needs. Although oxygen from the air is constantly taken by living beings for respiration, its reserves, nevertheless, never run out. Plants release it in the course of their nutrition, thereby replenishing our oxygen reserves.

From the book Who's Who in the Art World author Sitnikov Vitaly Pavlovich

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Why was the Lighthouse of Alexandria needed? In the 3rd century BC, a lighthouse was built in Egyptian Alexandria so that ships arriving in the bay of the city could successfully bypass the coastal reefs. This structure consisted of three marble towers, the uppermost of which resembled

From the book The World Around Us author Sitnikov Vitaly Pavlovich

Why does an orchestra need a conductor? If you have ever been to the opera house, you probably remember what an unimaginable noise is before the start of the performance. The great Igor Stravinsky conducts (1929) All the musicians gathered in the orchestra pit tune their

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Why is sleep needed? Sleep has always attracted the attention of people as an unusual and mysterious phenomenon. He caused misunderstanding, and sometimes fear. The dream seemed to be something close to death, which means that some deity should control it. For example, ancient greek god sleep Hypnos was part of the retinue

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Why do dogs need an owner? The belief that dogs need an owner is based on the often (but not always!) observable affection and devotion of dogs, and also on the fact that the person himself perceives himself as an owner. But the owner is a purely human, socio-psychological

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Why does a person need biotin? Biotin (vitamin H) is a coenzyme involved in the reactions of carbon dioxide transfer to organic compounds (for example, in the biosynthesis of fatty acids). Biotin is synthesized by the intestinal microflora, and therefore its insufficiency in humans

From the book The Newest Book of Facts. Volume 1 [Astronomy and astrophysics. Geography and other earth sciences. Biology and Medicine] author Kondrashov Anatoly Pavlovich

Why does a person need vitamin B6? Vitamin B6 plays an important role in protein metabolism and the synthesis of polyunsaturated fatty acids. It occurs naturally in three forms: pyridoxine, pyridoxal, and pyridoxamine. All forms of vitamin B6 are easily converted into each other in the body.

From the book The Newest Book of Facts. Volume 1 [Astronomy and astrophysics. Geography and other earth sciences. Biology and Medicine] author Kondrashov Anatoly Pavlovich

Why do you need human body riboflavin? Riboflavin (vitamin B2) is involved in the processes of tissue respiration and, therefore, contributes to the production of energy in the body. The lack of riboflavin leads to lesions of the skin, mucous membranes, to a violation

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From the book The Newest Book of Facts. Volume 1. Astronomy and astrophysics. Geography and other earth sciences. Biology and medicine author Kondrashov Anatoly Pavlovich

From the book Thematic Traffic: How to sell to someone who has not yet thought of buying by SEMANTICA

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Why do you need a man? One of the great women expressed an interesting thought: “Some women cry that they did not find the man of their dreams, while others cry that they did.” Most often, a woman thinks that if she finds the man of her dreams, that is, perfect man(the one she

From the book Why do some people love and marry others? Secrets of a Successful Marriage author Syabitova Rosa Raifovna

Why do we need a marriage contract Here the music has died down, the congratulations of the newlyweds have ended, and purely earthly everyday life begins. Not everyone manages to live happily in marriage - in love and harmony - and die on the same day. According to the State Statistics Committee, the number of divorces

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Why do you need a strong grip? In this case, it is worth considering why you need a strong grip? To be honest, neither in bodybuilding, much less in fitness, a strong grip is not a trait that is absolutely necessary to have. I never trained a grip, can't break a fat one

From the book Fallacies of Capitalism or the Pernicious Arrogance of Professor Hayek author Fet Abram Ilyich

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As it turned out, red blood cells, and in particular Hemoglobin, bring oxygen to the cells of the body.
Why does a cell need oxygen?

Oxygen

Features of the structure of the O molecule Atmospheric oxygen consists of diatomic molecules, in each O molecule there are 2 unpaired electrons.
Energy dissociation of the O molecule into atoms is quite high and is 493.57 kJ / mol.

The high strength of the chemical bond between atoms in the O molecule leads to the fact that at room temperature gaseous oxygen is chemically rather inactive. In nature, it slowly enters into transformations during the processes of decay. When heated, even a little, the chemical activity of oxygen increases dramatically. When ignited, it reacts with an explosion with hydrogen, methane, other combustible gases, with a large number of simple and complex substances.

Why does a cell need energy?

Every living cell must constantly produce energy. She needs energy to generate heat and synthesize ( create) some vital to her chemical substances, such as proteins or hereditary substance. Energy is needed by the cell, and in order to move.Body cells capable of making movements are called muscle cells. They may shrink. This sets in motion our arms, legs, heart, intestines. Finally, energy is needed to work out electricity : thanks to him, some parts of the body communicate with others. And the connection between them is primarily provided by nerve cells.

How does a cell get energy?

Cells burn nutrients, and in doing so, a certain amount of energy is released.They can do this in two ways.
First, burn carbohydrates, mainly glucose, in lack of oxygen. it is the oldest form of energy extraction and is very ineffective. Remember that life originated in water, that is, in an environment where there was very little oxygen.

Secondly, body cellsburn pyruvic acid, fats and proteins in the presence of oxygen.All of these substances contain carbon and hydrogen.Combustion of hydrogen in pure oxygenreleases a lot of energy

Remember TV reports from spaceports about rocket launches? They soar up due to the incredible amount of energy released during ... the oxidation of hydrogen, that is, when it is burned in oxygen.Space rockets as high as a tower rush into the sky due to the enormous energy that is released when hydrogen is burned in pure oxygen.Their fuel tanks are filled with liquid hydrogen and oxygen. When the engines are started, the hydrogen begins to oxidize and the huge rocket is rapidly carried away into the sky. Maybe it seems incredible, and yet: the same energy that takes you up space rocket, maintains life in the cells of our body.This same energy sustains life in the cells of our body.Unless there is no explosion in the cells and a sheaf of flame does not break out of them. Oxidation takes place in stages, and therefore, instead of thermal and kinetic energy, ATP molecules are formed.