Internal respiration and transport of gases. The chemical composition of air and its hygienic significance

atmospheric air, which a person inhales while outdoors (or in well-ventilated rooms), contains 20.94% oxygen, 0.03% carbon dioxide, 79.03% nitrogen. In enclosed spaces filled with people, the percentage of carbon dioxide in the air can be slightly higher.

Exhaled air contains an average of 16.3% oxygen, 4% carbon dioxide, 79.7% nitrogen (these figures are given in terms of dry air, that is, excluding water vapor, which is always saturated with exhaled air).

Composition of exhaled air very fickle; it depends on the intensity of the body's metabolism and on the volume of pulmonary ventilation. It is worth taking a few deep breathing movements or, on the contrary, holding your breath so that the composition of the exhaled air changes.

Nitrogen does not participate in gas exchange, however, the percentage of nitrogen in visible air is several tenths of a percent higher than in inhaled air. The fact is that the volume of exhaled air is somewhat less than the volume of inhaled air, and therefore the same amount of nitrogen, distributed in a smaller volume, gives a larger percentage. The smaller volume of exhaled air compared to the volume of inhaled air is due to the fact that slightly less carbon dioxide is released than oxygen is absorbed (part of the absorbed oxygen is used in the body to circulate compounds that are excreted from the body with urine and sweat).

Alveolar air differs from exhaled by a large percentage of non-acid and a smaller percentage of oxygen. On average, the composition of alveolar air is as follows: oxygen 14.2-14.0%, carbon dioxide 5.5-5.7%, nitrogen about 80%.

Definition composition of alveolar air important for understanding the mechanism of gas exchange in the lungs. Holden proposed a simple method for determining the composition of alveolar air. After a normal inhalation, the subject exhales as deeply as possible through a tube 1-1.2 m long and 25 mm in diameter. The first portions of exhaled air leaving through the tube contain the air of the harmful space; the last portions remaining in the tube contain alveolar air. For analysis, air is taken into the gas receiver from that part of the tube that is closest to the mouth.

The composition of the alveolar air varies somewhat depending on whether the air sample was taken for analysis at the height of inhalation or exhalation. If you make a quick, short and incomplete expiration at the end of a normal inspiration, then the air sample will reflect the composition of the alveolar air after filling the lungs with respiratory air, i.e. during inspiration. If you take a deep breath after a normal exhalation, then the sample will reflect the composition of the alveolar air during exhalation. It is clear that in the first case, the percentage of carbon dioxide will be somewhat less, and the percentage of oxygen will be somewhat greater than in the second. This can be seen from the results of Holden's experiments, who found that the percentage of carbon dioxide in the alveolar air at the end of inspiration is on average 5.54, and at the end of expiration - 5.72.

Thus, there is a relatively small difference in the content of carbon dioxide in the alveolar air during inhalation and exhalation: only 0.2-0.3%. This is largely due to the fact that during normal breathing, as mentioned above, only 1/7 of the volume of air in the pulmonary alveoli is renewed. The relative constancy of the composition of the alveolar air is of great physiological importance, as will be explained below.

The remaining 1-1.5% of the volume is mostly argon and carbon dioxide, as well as a small amount of other gases - neon, helium, xenon and others. At the same time, the proportion of carbon dioxide in ordinary atmospheric air, not subject to any influence, most often is about 0.3% by volume.

Exhaled air

At the same time, the composition of the air, which is obtained as a result of the human respiratory process, differs significantly from the original one in terms of the content of a number of elements. So, it is known that in the process of breathing the human body consumes oxygen, therefore it is natural that its amount in exhaled air is significantly less than in inhaled air. If the initial composition of the air contained about 21% oxygen, then in the air on exhalation it will be only about 15.4%.

Another significant change that occurs to the air during respiration concerns the content of carbon dioxide. So, if in the air entering the human body, its content usually does not exceed 0.3% of the volume, then in the air leaving the body the volume of carbon dioxide reaches 4%. This is due to the fact that during the functioning of the human body, its organs and tissues emit carbon dioxide, which is excreted during respiration. But the content of other gases in the exhaled air practically does not change in relation to the original. This is due to the fact that for the human body they are inert, that is, they do not interact with it in any way - they are not absorbed and not excreted.

At the same time, it should be borne in mind that the air exhaled by a person changes not only its composition, but also some physical characteristics. Its temperature approaches the temperature of the human body, which is normally 36.6 ° C. Thus, if a person breathes cold air, its temperature will increase, and if it is hot, it will decrease. In addition, exhaled air is usually characterized by more high level humidity compared to inhaled.

Air is natural mixture various gases. Most of all, it contains elements such as nitrogen (about 77%) and oxygen, less than 2% are argon, carbon dioxide and other inert gases.

Oxygen, or O2, is the second element of the periodic table and the most important component, without which life would hardly exist on the planet. He participates in various processes on which all living things depend.

In contact with

Composition of air

O2 performs the function oxidative processes in the human body, which allow you to release energy for normal life. At rest, the human body requires about 350 milliliters of oxygen, with severe physical activity this value increases three to four times.

What percentage of oxygen is in the air we breathe? The norm is 20,95% . Exhaled air contains less O2 - 15.5-16%. The composition of exhaled air also includes carbon dioxide, nitrogen and other substances. A subsequent decrease in the percentage of oxygen leads to a malfunction, and a critical value of 7-8% causes fatal outcome.

From the table it can be understood, for example, that exhaled air contains a lot of nitrogen and additional elements, and here O2 only 16.3%. The oxygen content of the inhaled air is approximately 20.95%.

It is important to understand what an element such as oxygen is. O2 - the most common on earth chemical element which is colorless, odorless and tasteless. It performs the most important function of oxidation in.

Without the eighth element of the periodic table can't get fire. Dry oxygen improves electrical and protective properties films, to reduce their space charge.

This element is contained in the following compounds:

1. Silicates - they contain approximately 48% O2.
2. (marine and fresh) - 89%.
3. Air - 21%.
4. Other compounds in the earth's crust.

Air contains not only gaseous substances, but also vapors and aerosols and various contaminants. It can be dust, dirt, other various small debris. It contains microbes that can cause various diseases. Influenza, measles, whooping cough, allergens and other diseases - this is just a small list negative consequences, which appear when the air quality deteriorates and the level of pathogenic bacteria increases.

The percentage of air is the amount of all the elements that make up it. It is more convenient to show clearly what the air consists of, as well as the percentage of oxygen in the air, on the diagram.

The diagram shows which gas contains more in the air. The values ​​given on it will be slightly different for inhaled and exhaled air.

Diagram - air ratio.

There are several sources from which oxygen is formed:

1. Plants. Even from the school biology course, it is known that plants release oxygen when they absorb carbon dioxide.
2. Photochemical decomposition of water vapor. The process is observed under the action solar radiation in top layer atmosphere.
3. Mixing of air streams in the lower atmospheric layers.

The functions of oxygen in the atmosphere and for the body

For a person, the so-called partial pressure, which the gas could produce if it occupied the entire occupied volume of the mixture. The normal partial pressure at 0 meters above sea level is 160 millimeters mercury column . An increase in altitude causes a decrease in partial pressure. This indicator is important, since the supply of oxygen to all important organs and in depends on it.

Oxygen is often used for treatment various diseases . Oxygen cylinders, inhalers help human organs to function normally in the presence of oxygen starvation.

Important! The composition of the air is influenced by many factors, respectively, the percentage of oxygen can change. The negative environmental situation leads to a deterioration in air quality. In megacities and large urban settlements, the proportion of carbon dioxide (CO2) will be greater than in small settlements or in forest and protected areas. Big influence Altitude also has an effect - the percentage of oxygen will be less in the mountains. We can consider the following example - on Mount Everest, which reaches a height of 8.8 km, the concentration of oxygen in the air will be 3 times lower than in the lowland. For a safe stay on high mountain peaks, you need to use oxygen masks.

The composition of the air has changed over the years. Evolutionary processes, natural disasters have led to changes in, therefore decreased percentage of oxygen required for normal operation bioorganisms. Several historical stages can be considered:

1. prehistoric era. At that time, the concentration of oxygen in the atmosphere was about 36%.
2. 150 years ago O2 occupied 26% from the total air composition.
3. At present, the concentration of oxygen in the air is just under 21%.

The subsequent development of the surrounding world can lead to a further change in the composition of the air. It is unlikely for the foreseeable future that the O2 concentration could be below 14%, as this would cause disruption of the body.

What does lack of oxygen lead to?

Low intake is most often observed in stuffy vehicles, poorly ventilated rooms or at height . Decreased oxygen levels in the air can cause Negative influence on the body. There is an exhaustion of mechanisms, the greatest influence is nervous system. There are several reasons why the body suffers from hypoxia:

1. Blood deficiency. called in case of poisoning carbon monoxide . This situation lowers the oxygen component of the blood. This is dangerous because the blood stops delivering oxygen to hemoglobin.
2. circulatory deficiency. It is possible with diabetes, heart failure. In such a situation, blood transport worsens or becomes impossible.
3. Histotoxic factors affecting the body can cause the loss of the ability to absorb oxygen. Arises in case of poisoning or due to heavy exposure.

According to a number of symptoms, it can be understood that the body needs O2. Primarily increased breathing rate. It also increases the heart rate. These protective functions are designed to supply oxygen to the lungs and provide them with blood and tissues.

The lack of oxygen causes headaches, increased drowsiness, deterioration in concentration. Isolated cases are not so terrible, they are quite easy to correct. To normalize respiratory failure, the doctor prescribes bronchodilator drugs and other drugs. If hypoxia takes severe forms, such as loss of a person's coordination or even a comatose state the treatment becomes more difficult.

If symptoms of hypoxia are found, it is important consult a doctor immediately and not to self-medicate, since the use of one or another medicinal product depends on the cause of the violation. Helps for mild cases oxygen mask treatment and pillows, blood hypoxia requires a blood transfusion, and the correction of circular causes is possible only with surgery on the heart or blood vessels.

The incredible journey of oxygen through our body

Conclusion

Oxygen is the most important air component, without which it is impossible to carry out many processes on Earth. Air Composition changed over tens of thousands of years due to evolutionary processes, but now the amount of oxygen in the atmosphere has reached the value at 21%. The quality of the air a person breathes affects his health therefore, it is necessary to monitor its cleanliness in the room and try to reduce environmental pollution.

Composition of inhaled and exhaled air

Physiology of respiration

The vital activity of a living organism is associated with its absorption of O 2 and the release of CO 2. For this reason, the concept of respiration includes all the processes associated with the delivery of O 2 from external environment inside the cells and the release of CO 2 from the cell into environment.

Under the physiology of respiration understand the following processes: external respiration, gas exchange in the lungs, transport of gases by blood, tissue and cellular respiration.

External respiration is carried out by the human respiratory apparatus. It includes the chest with the muscles that set it in motion and the lungs with the airways. The main respiratory muscles are the diaphragm and intercostal muscles - internal and external.

When you inhale, the muscle fibers of the diaphragm contract, it flattens and falls down. In this case, the chest increases in the vertical direction. The contraction of the external costal muscles raises the ribs and pushes them to the sides, and the sternum forward. In this case, the chest expands in the transverse and anteroposterior directions. With the expansion of the chest cavity, the lungs passively expand due to atmospheric pressure acting through the airways on the inner surface of the lungs. With the expansion of the lungs, the air in them is distributed in a larger volume and the pressure in the cavity of the lungs becomes lower than atmospheric pressure (by 3-4 mm Hg). The pressure difference is the reason that atmospheric air begins to flow into the lungs - inhalation occurs.

Exhalation is carried out as a result of relaxation of the respiratory muscles. When their contraction stops, the chest descends and returns to its original position. The relaxed diaphragm rises and takes the shape of a dome. Distended lungs decrease in volume. All taken together leads to an increase in intrapulmonary pressure. The air comes out of the lungs out - there is an exhalation.

Gas exchange or ventilation of the lungs - ϶ᴛᴏ the volume of air passing through the lungs in one minute - the minute volume of breathing. At rest, it is equal to 5-8 l / min, with muscular work it increases.

A person inhales atmospheric air, which contains 20.94% oxygen, 78.03% nitrogen and 0.03% carbon dioxide. Exhaled air contains less oxygen (16.3%) and 4% carbon dioxide. Due to the difference in the partial pressure of O 2 in the inhaled and exhaled air, oxygen from the air enters the alveoli of the lungs. The partial pressure of CO 2 in the capillaries of venous blood is 47 mm Hg, and the partial pressure of CO 2 in the alveoli is 40. Due to the difference in partial pressure, CO 2 from the venous blood goes into the air. Nitrogen does not participate in gas exchange. The conditions for gas exchange in the lungs are so favorable that, despite the fact that the time of passage of blood through the capillaries of the lungs is about 1 second, the tension of gases in the alveolar blood flowing from the lungs is the same as it would be after prolonged contact.

If the ventilation of the lungs is insufficient and the content of CO 2 increases in the alveoli, then the level of CO 2 in the blood also rises, which immediately leads to an increase in breathing - shortness of breath.

Carrying gases in the blood.

Gases are very slightly soluble in liquid: 100 ml of blood can physically dissolve about 2% oxygen and 3-4% carbon dioxide. But red blood cells contain hemoglobin, which is able to chemically bind O 2 and CO 2. The combination of hemoglobin with oxygen is commonly called oxyhemoglobin Hb + O 2 ®HbO 2, which is contained in arterial blood. Oxyhemoglobin is not a strong connection, given that human blood contains about 15% hemoglobin, then 100 ml of blood can bring up to 21 ml of O 2. This is the so-called oxygen capacity of the blood. Oxyhemoglobin with arterial blood is sent to tissues and cells, where, as a result of continuously ongoing oxidative processes, O 2 is consumed. Hemoglobin picks up carbon dioxide released from the tissues and an unstable compound HbCO 2 - carbhemoglobin is formed. About 10% of the released carbon dioxide enters into such a compound. The rest combines with water and turns into carbonic acid. This reaction is accelerated thousands of times by a special enzyme - carbonic anhydrase, located in red blood cells. Further, carbonic acid in tissue capillaries reacts with sodium and potassium ions, forming bicarbonates (NaHCO 3 , KHCO 3). All these compounds are transported to the lungs.

Hemoglobin combines particularly readily with carbon monoxide CO 2 (carbon monoxide) to form carboxyhemoglobin, which is incapable of carrying oxygen. Its chemical affinity for hemoglobin is almost 300 times higher than for O 2 . Thus, at a concentration of CO in the air equal to 0.1%, about 80% of the hemoglobin in the blood is associated not with oxygen, but with carbon monoxide. As a result, symptoms of oxygen starvation appear in the human body (vomiting, headache, loss of consciousness). Mild carbon monoxide poisoning is a reversible process: CO is gradually split off from hemoglobin and excreted during breathing fresh air. In severe cases, death occurs.

The composition of inhaled and exhaled air - the concept and types. Classification and features of the category "Composition of inhaled and exhaled air" 2017, 2018.

We all know very well that without air on earth not a single one will live. creature. Air is vital for all of us. Everyone from children to adults knows that it is impossible to survive without air, but not everyone knows what air is and what it consists of. So, air is a mixture of gases that cannot be seen or touched, but we all know perfectly well that it is around us, although we practically do not notice it. To conduct research of a different nature, including, it is possible in our laboratory.

We can only feel the air when we feel strong wind or we are near the fan. What does air consist of, and it consists of nitrogen and oxygen, and only a small part of argon, water, hydrogen and carbon dioxide. If we consider the composition of air as a percentage, then nitrogen is 78.08 percent, oxygen 20.94%, argon 0.93 percent, carbon dioxide 0.04 percent, neon 1.82 * 10-3 percent, helium 4.6 * 10-4 percent, methane 1.7 * 10-4 percent, krypton 1.14*10-4 percent, hydrogen 5*10-5 percent, xenon 8.7*10-6 percent, nitrous oxide 5*10-5 percent.

The oxygen content in the air is very high because it is oxygen that is necessary for the life of the human body. Oxygen, which is observed in the air during breathing, enters the cells of the human body, and participates in the oxidation process, as a result of which the energy that is needed for life is released. Also, oxygen, which is in the air, is also required for burning fuel, which produces heat, as well as when receiving mechanical energy in internal combustion engines.

Inert gases are also extracted from the air during liquefaction. How much oxygen is in the air, if you look at the percentage, then oxygen and nitrogen in the air is 98 percent. Knowing the answer to this question, another one arises, which gaseous substances are still part of the air.

So, in 1754, a scientist named Joseph Black confirmed that the air consists of a mixture of gases, and not a homogeneous substance as previously thought. The composition of air on earth includes methane, argon, carbon dioxide, helium, krypton, hydrogen, neon, xenon. It is worth noting that the percentage of air can vary slightly depending on where people live.

Unfortunately, in major cities the proportion of carbon dioxide as a percentage will be higher than, for example, in villages or forests. The question arises how many percent of oxygen is in the air in the mountains. The answer is simple, oxygen is much heavier than nitrogen, so there will be much less of it in the air in the mountains, this is because the density of oxygen decreases with height.

The rate of oxygen in the air

So, with regard to the ratio of oxygen in the air, there are certain standards, for example, for working area. In order for a person to be able to fully work, the norm of oxygen in the air is from 19 to 23 percent. When operating equipment in enterprises, it is imperative to monitor the tightness of the devices, as well as various machines. If, when testing the air in a room where people work, the oxygen indicator is below 19 percent, then it is imperative to leave the room and turn on emergency ventilation. You can control the level of oxygen in the air at the workplace by inviting the EcoTestExpress laboratory and researching it.

Let's now define what oxygen is.

Oxygen is chemical element According to Mendeleev's periodic table of elements, oxygen has no smell, no taste, no color. Oxygen in the air is essential for human respiration, as well as for combustion, because it is no secret to anyone that if there is no air, then no materials will burn. Oxygen contains a mixture of three stable nuclides, mass numbers which are 16. 17 and 18.

So, oxygen is the most common element on earth, with regard to the percentage of oxygen, the largest percentage is in silicates, which is about 47.4 percent of the mass of solid earth's crust. Also in marine and fresh waters The entire earth contains a huge amount of oxygen, namely 88.8 percent, as for the amount of oxygen in the air, it is only 20.95 percent. It should also be noted that oxygen is part of more than 1500 compounds in the earth's crust.

As for the production of oxygen, it is obtained by separating air at low temperatures. This process occurs as follows, at the beginning they compress the air with the help of a compressor, while compressing the air, it begins to heat up. compressed air allow to cool to room temperature, and after cooling provide its free expansion.

When expansion occurs, the gas temperature begins to drop sharply, after the air has cooled, its temperature can be several tens of degrees lower than room temperature, such air is again subjected to compression and the released heat is taken away. After several stages of air compression and cooling, a number of procedures are performed as a result of which pure oxygen is separated without any impurities.

And here another question arises which is heavier oxygen or carbon dioxide. The answer is simply of course carbon dioxide will be heavier than oxygen. The density of carbon dioxide is 1.97 kg/m3, while the density of oxygen is 1.43 kg/m3. As for carbon dioxide, as it turns out, it plays one of the main roles in the life of all life on earth, and also has an impact on the carbon cycle in nature. It has been proven that carbon dioxide is involved in the regulation of respiration, as well as blood circulation.

What is carbon dioxide?

Now let's define in more detail what carbon dioxide is, and also denote the composition of carbon dioxide. So, carbon dioxide in other words is carbon dioxide, it is a colorless gas with a slightly sour smell and taste. As for the air, the concentration of carbon dioxide in it is 0.038 percent. physical properties carbon dioxide is that it does not exist in liquid state under normal atmospheric pressure and goes directly from the solid to the gaseous state.

Carbon dioxide in the solid state is also called dry ice. To date, carbon dioxide is a participant global warming. They produce carbon dioxide by burning various substances. It is worth noting that at industrial production carbon dioxide is pumped into cylinders. Carbon dioxide pumped into cylinders is used as fire extinguishers, as well as in the production of soda water, and is also used in pneumatic weapons. And also in Food Industry as a preservative.

Composition of inhaled and exhaled air

Now let's analyze the composition of the inhaled and exhaled air. First, let's define what breathing is. Breathing is called a complex continuous process, with the help of which it is constantly updated gas composition blood. The composition of the air we breathe is 20.94 percent oxygen, 0.03 percent carbon dioxide, and 79.03 percent nitrogen. But the composition of the exhaled air is already only 16.3 percent oxygen, as much as 4 percent carbon dioxide and 79.7 percent nitrogen.

It can be seen that the inhaled air differs from the exhaled by the content of oxygen, as well as the amount of carbon dioxide. These are the substances that make up the air we breathe and exhale. Thus, our body is saturated with oxygen and releases all unnecessary carbon dioxide to the outside.

Dry oxygen improves the electrical and protective properties of the films due to the absence of water, as well as their compaction and reduction of the space charge. Also, dry oxygen under normal conditions cannot react with gold, copper or silver. To spend chemical analysis air or other laboratory research, including, is possible in our laboratory "EkoTestEkspress".

Air is the atmosphere of the planet on which we live. And we always have the question of what is part of the air, the answer is simply a set of gases, as it has already been described above, which gases and in what proportion are in the air. As for the content of gases in the air, everything is easy and simple here, the percentage ratio for almost all areas of our planet is the same.

Composition and properties of air

Air consists not only of a mixture of gases, but also of various aerosols and vapors. The percentage composition of air is the ratio of nitrogen to oxygen and other gases in the air. So, how much oxygen is in the air, the simple answer is only 20 percent. Component composition gas, as for nitrogen, it contains the lion's share of all air, and it is worth noting that when high blood pressure nitrogen begins to have narcotic properties.

This is of no small importance, because during the work of divers, they often have to work at depths under enormous pressure. A lot has already been said about oxygen, because it is of great importance for human life on our planet. It is worth noting that the inhalation of air with high oxygen by a person in a short period does not adversely affect the person himself.

But if a person breathes air with increased level oxygen for a long time, it will lead to pathological changes in the body. Another main component of the air, about which much has already been said, is carbon dioxide, as it turns out, a person cannot live without it as well as without oxygen.

If there was no air on earth, then not one living organism could live on our planet, much less function somehow. Unfortunately, in modern world great amount industrial facilities that pollute our air recent times more and more people are calling for the need to protect the environment, as well as to monitor the cleanliness of the air. Therefore, frequent air measurements should be taken to determine how clean it is. If it seems to you that the air in your room is not clean enough and there are external factors to blame, you can always contact the EcoTestExpress laboratory, which will conduct everything necessary tests( , research ) and will give a conclusion about the purity of the air you breathe.