What is the expiratory reserve volume. Lung volumes and lung capacities. Lung volumes and capacities

The total lung capacity of an adult male is on average 5-6 liters, but during normal breathing only a small part of this volume is used. With calm breathing, a person performs about 12-16 respiratory cycles, inhaling and exhaling about 500 ml of air in each cycle. This volume of air is called the respiratory volume. With a deep breath, you can additionally inhale 1.5-2 liters of air - this is the reserve volume of inspiration. The volume of air that remains in the lungs after maximum expiration is 1.2-1.5 liters - this is the residual volume of the lungs.

Measurement of lung volumes

Under the term measurement of lung volumes commonly understood as the measurement of total lung capacity (TLC), residual lung volume (RRL), functional residual capacity (FRC) of the lungs and vital capacity (VC). These indicators play a significant role in the analysis of the ventilation capacity of the lungs, they are indispensable in the diagnosis of restrictive ventilation disorders and help evaluate the effectiveness of the therapeutic intervention. The measurement of lung volumes can be divided into two main steps: the measurement of the FRC and the performance of a spirometry study.

To determine the FRC, one of the three most common methods is used:

1. gas dilution method (gas dilution method);
2. body plethysmographic;
3. radiological.

Lung volumes and capacities

Usually, four lung volumes are distinguished - inspiratory reserve volume (IRV), tidal volume (TO), expiratory reserve volume (ERV) and residual lung volume (ROL) and the following capacities: vital capacity (VC), inspiratory capacity (Evd), functional residual capacity (FRC) and total lung capacity (TLC).

The total lung capacity can be represented as the sum of several lung volumes and capacities. Lung capacity is the sum of two or more lung volumes.

Tidal volume (TO) is the volume of gas that is inhaled and exhaled during a respiratory cycle during quiet breathing. DO should be calculated as an average after recording at least six respiratory cycles. The end of the inspiratory phase is called the end-inspiratory level, the end of the exhalation phase is called the end-expiratory level.

Inspiratory reserve volume (IRV) is the maximum volume of air that can be inhaled after a normal average quiet breath (end-inspiratory level).

Expiratory reserve volume (ERV) is the maximum volume of air that can be exhaled after a quiet exhalation (end-expiratory level).

Residual lung volume (RLV) is the volume of air that remains in the lungs after a full exhalation. TRL cannot be measured directly, it is calculated by subtracting the EV from the FRC: OOL \u003d FOE - ROvyd or OOL \u003d OEL - VC. Preference is given to the latter method.

Vital capacity (VC) - the volume of air that can be exhaled during a full exhalation after a maximum inspiration. With a forced exhalation, this volume is called the forced vital capacity of the lungs (FVC), with a calm maximum (inhalation) exhalation - the vital capacity of the lungs of inhalation (exhalation) - FVC (VC). ZhEL includes DO, ROVD and ROVID. The VC is normally approximately 70% of the TRL.

Inspiratory capacity (EVD) - the maximum volume that can be inhaled after a quiet exhalation (from the end-expiratory level). EVD is equal to the sum of DO and ROVD and normally is usually 60-70% VC.

Functional residual capacity (FRC) is the volume of air in the lungs and airways after a quiet exhalation. The FRC is also referred to as the final expiratory volume. FFU includes ROvyd and OOL. Measurement of FRC is a defining step in assessing lung volumes.

Total lung capacity (TLC) is the volume of air in the lungs at the end of a full breath. The REL is calculated in two ways: OEL \u003d OOL + VC or OEL \u003d FOE + Evd. The latter method is preferable.

Measurement of the total lung capacity and its components is widely used in various diseases and provides significant assistance in the diagnostic process. For example, with emphysema, there is usually a decrease in FVC and FEV1, the FEV1 / FVC ratio is also reduced. A decrease in FVC and FEV1 is also noted in patients with restrictive disorders, but the FEV1/FVC ratio is not reduced.

Despite this, the FEV1/FVC ratio is not a key parameter in the differential diagnosis of obstructive and restrictive disorders. For the differential diagnosis of these ventilation disorders, it is necessary to measure the RFE and its components. With restrictive violations, there is a decrease in the TRL and all its components. In obstructive and combined obstructive-restrictive disorders, some components of the REL are reduced, some are increased.

The FRC measurement is one of the two main steps in the measurement of the RFE. FRC can be measured by gas dilution methods, body plethysmography or radiography. In healthy individuals, all three methods allow obtaining similar results. The coefficient of variation of repeated measurements in the same subject is usually below 10%.

The gas dilution method is widely used because of the simplicity of the technique and the relative cheapness of the equipment. However, in patients with severe bronchial conduction disorders or emphysema, the true TEL value measured by this method is underestimated because the inhaled gas does not penetrate into hypoventilated and unventilated spaces.

The body plethysmography method allows you to determine the intrathoracic volume (VGO) of gas. Thus, FRC measured by body plethysmography includes both ventilated and non-ventilated lung regions. In this regard, in patients with pulmonary cysts and air traps, this method gives higher rates compared to the method of diluting gases. Body plethysmography is a more expensive method, technically more difficult and requires more effort and cooperation from the patient compared to the gas dilution method. Nevertheless, the body plethysmography method is preferable, since it allows a more accurate assessment of the FRC.

The difference between the values ​​obtained using these two methods provides important information about the presence of unventilated air space in the chest. With severe bronchial obstruction, the method of general plethysmography may overestimate the FRC.

Based on the materials of A.G. Chuchalin

Lung ventilation is a continuous regulated process of updating the gas composition of the air contained in the lungs. Ventilation of the lungs is provided by the introduction of atmospheric air rich in oxygen into them, and the removal of gas containing excess carbon dioxide during exhalation.

Pulmonary ventilation is characterized by minute respiratory volume. At rest, an adult inhales and exhales 500 ml of air at a frequency of 16-20 times per minute (minute 8-10 liters), a newborn breathes more often - 60 times, a child of 5 years old - 25 times per minute. The volume of the respiratory tract (where gas exchange does not occur) - 140 ml, the so-called air of the harmful space; thus, 360 ml enters the alveoli. Rare and deep breathing reduces the amount of harmful space, and it is much more effective.

Static volumes include values ​​that are measured after the completion of a respiratory maneuver without limiting the speed (time) of its implementation.

The static indicators include four primary lung volumes: - tidal volume (TO - VT);

Inspiratory reserve volume (IRV);

Expiratory reserve volume (ERV - ERV);

Residual volume (OO - RV).

As well as containers:

Vital capacity of the lungs (VC - VC);

Inspiratory capacity (Evd - IC);

Functional residual capacity (FRC - FRC);

Total lung capacity (TLC).

Dynamic quantities characterize the volumetric velocity of the air flow. They are determined taking into account the time spent on the implementation of the respiratory maneuver. Dynamic indicators include:

Forced expiratory volume in the first second (FEV 1 - FEV 1);

Forced vital capacity (FZhEL - FVC);

Peak volumetric (PEV) expiratory flow rate (PEV), etc.

The volume and capacity of the lungs of a healthy person is determined by a number of factors:

1) height, body weight, age, race, constitutional features of a person;

2) elastic properties of lung tissue and airways;

3) contractile characteristics of the inspiratory and expiratory muscles.

Spirometry, spirography, pneumotachometry and body plethysmography are used to determine lung volumes and capacities.

For comparability of the results of measurements of lung volumes and capacities, the obtained data should be correlated with standard conditions: body temperature 37 ° C, atmospheric pressure 101 kPa (760 mm Hg), relative humidity 100%.

Tidal volume

Tidal volume (TO) is the volume of air inhaled and exhaled during normal breathing, equal to an average of 500 ml (with fluctuations from 300 to 900 ml).

About 150 ml of it is the volume of functional dead space air (VFMP) in the larynx, trachea, bronchi, which does not take part in gas exchange. The functional role of the HFMP is that it mixes with the inhaled air, humidifying and warming it.

expiratory reserve volume

The expiratory reserve volume is the volume of air equal to 1500-2000 ml, which a person can exhale if, after a normal exhalation, he makes a maximum exhalation.

Inspiratory reserve volume

Inspiratory reserve volume is the volume of air that a person can inhale if, after a normal inspiration, he takes a maximum breath. Equal 1500 - 2000 ml.

Vital capacity of the lungs

Vital capacity (VC) - the maximum amount of air exhaled after the deepest breath. VC is one of the main indicators of the state of the external respiration apparatus, widely used in medicine. Together with the residual volume, i.e. the volume of air remaining in the lungs after the deepest exhalation, the VC forms the total lung capacity (TLC).

Normally, VC is about 3/4 of the total lung capacity and characterizes the maximum volume within which a person can change the depth of his breathing. With calm breathing, a healthy adult uses a small part of the VC: inhales and exhales 300-500 ml of air (the so-called tidal volume). At the same time, the inspiratory reserve volume, i.e. the amount of air that a person is able to inhale additionally after a quiet breath, and the expiratory reserve volume, equal to the volume of additionally exhaled air after a quiet exhalation, averages about 1500 ml each. During exercise, tidal volume increases by using the inspiratory and expiratory reserves.

The vital capacity of the lungs is an indicator of the mobility of the lungs and chest. Despite the name, it does not reflect the parameters of respiration in real (“life”) conditions, since even with the highest needs that the body has for the respiratory system, the depth of respiration never reaches the maximum possible value.

From a practical point of view, it is not advisable to establish a “single” norm for the vital capacity of the lungs, since this value depends on a number of factors, in particular, on age, gender, body size and position, and the degree of fitness.

With age, the vital capacity of the lungs decreases (especially after 40 years). This is due to a decrease in the elasticity of the lungs and the mobility of the chest. Women have an average of 25% less than men.

Growth dependence can be calculated using the following equation:

VC=2.5*height (m)

VC depends on the position of the body: in a vertical position, it is somewhat greater than in a horizontal position.

This is explained by the fact that in an upright position, less blood is contained in the lungs. In trained people (especially swimmers, rowers), it can be up to 8 liters, since athletes have highly developed auxiliary respiratory muscles (pectoralis major and minor).

Residual volume

Residual volume (VR) is the volume of air that remains in the lungs after maximum exhalation. Equal 1000 - 1500 ml.

Total lung capacity

The total (maximum) lung capacity (TLC) is the sum of respiratory, reserve (inhalation and exhalation) and residual volumes and is 5000 - 6000 ml.

The study of respiratory volumes is necessary to assess the compensation of respiratory failure by increasing the depth of breathing (inhalation and exhalation).

Vital capacity of the lungs. Systematic physical education and sports contribute to the development of respiratory muscles and expansion of the chest. Already 6-7 months after the start of swimming or running, the vital capacity of the lungs in young athletes can increase by 500 cc. and more. Its decrease is a sign of overwork.

The vital capacity of the lungs is measured with a special device - a spirometer. To do this, first close the hole in the inner cylinder of the spirometer with a cork and disinfect its mouthpiece with alcohol. After a deep breath, take a deep breath through the mouthpiece taken into your mouth. In this case, the air should not pass by the mouthpiece or through the nose.

The measurement is repeated twice, and the highest result is recorded in the diary.

The vital capacity of the lungs in humans ranges from 2.5 to 5 liters, and in some athletes it reaches 5.5 liters or more. The vital capacity of the lungs depends on age, gender, physical development and other factors. Reducing it by more than 300 cc may indicate overwork.

It is very important to learn full deep breathing, to avoid delaying it. If at rest the respiratory rate is usually 16-18 per minute, then during physical exertion, when the body needs more oxygen, this frequency can reach 40 or more. If you experience frequent shallow breathing, shortness of breath, you need to stop exercising, note this in the self-control diary and consult a doctor.

For a freediver, the lungs are the main "working tool" (of course, after the brain), so it is important for us to understand the structure of the lungs and the whole process of breathing. Usually, when we talk about respiration, we mean external respiration or ventilation of the lungs - the only process in the respiratory chain that we notice. And consider breathing should begin with it.

The structure of the lungs and chest

The lungs are a porous organ, similar to a sponge, resembling in its structure an accumulation of individual bubbles or a bunch of grapes with a large number of berries. Each "berry" is a pulmonary alveolus (pulmonary vesicle) - a place where the main function of the lungs is performed - gas exchange. Between the air of the alveoli and the blood lies an air-blood barrier formed by very thin walls of the alveoli and the blood capillary. It is through this barrier that diffusion of gases occurs: oxygen enters the blood from the alveoli, and carbon dioxide enters the alveolus from the blood.

Air enters the alveoli through the airways - trochea, bronchi and smaller bronchioles, which end in alveolar sacs. The branching of the bronchi and bronchioles forms lobes (the right lung has 3 lobes, the left has 2 lobes). On average, in both lungs there are about 500-700 million alveoli, the respiratory surface of which ranges from 40 m 2 when exhaling to 120 m 2 when inhaling. In this case, a greater number of alveoli are located in the lower sections of the lungs.

The bronchi and trachea have a cartilaginous base in their walls and are therefore quite rigid. Bronchioles and alveoli are soft-walled and therefore can collapse, that is, stick together like a deflated balloon, if some air pressure is not maintained in them. To prevent this from happening, the lungs, as a single organ, are covered on all sides with a pleura - a strong hermetic membrane.

The pleura has two layers - two leaves. One sheet is tightly attached to the inner surface of the rigid chest, the other surrounds the lungs. Between them is the pleural cavity, which maintains negative pressure. Due to this, the lungs are in a straightened state. Negative pressure in the pleural space is due to the elastic recoil of the lungs, that is, the constant desire of the lungs to reduce their volume.

The elastic recoil of the lungs is due to three factors:
1) the elasticity of the tissue of the walls of the alveoli due to the presence of elastic fibers in them
2) bronchial muscle tone
3) surface tension of the liquid film covering the inner surface of the alveoli.

The rigid frame of the chest is made up of ribs, which are flexible, thanks to cartilage and joints, attached to the spine and joints. Due to this, the chest increases and decreases in volume, while maintaining the rigidity necessary to protect the organs located in the chest cavity.

In order to inhale air, we need to create a lower pressure in the lungs than atmospheric pressure, and to exhale a higher one. Thus, for inhalation it is necessary to increase the volume of the chest, for exhalation - a decrease in volume. In fact, most of the effort of breathing is spent on inhalation; under normal conditions, exhalation is carried out due to the elastic properties of the lungs.

The main respiratory muscle is the diaphragm - a domed muscular partition between the chest cavity and the abdominal cavity. Conventionally, its boundary can be drawn along the lower edge of the ribs.

When inhaling, the diaphragm contracts, stretching with an active action towards the lower internal organs. In this case, the incompressible organs of the abdominal cavity are pushed down and to the sides, stretching the walls of the abdominal cavity. With a quiet breath, the dome of the diaphragm descends by approximately 1.5 cm, and the vertical size of the chest cavity increases accordingly. At the same time, the lower ribs diverge somewhat, increasing the girth of the chest, which is especially noticeable in the lower sections. When exhaling, the diaphragm passively relaxes and is pulled up by the tendons holding it to its calm state.

In addition to the diaphragm, the external oblique intercostal and intercartilaginous muscles also take part in the increase in the volume of the chest. As a result of the rise of the ribs, the displacement of the sternum forward and the departure of the lateral parts of the ribs to the sides increase.

With very deep intensive breathing or with an increase in inhalation resistance, a number of auxiliary respiratory muscles are included in the process of increasing the volume of the chest, which can raise the ribs: scalariform, pectoralis major and minor, serratus anterior. The auxiliary muscles of inhalation also include the muscles that extensor the thoracic spine and fix the shoulder girdle when supported by arms folded back (trapezius, rhomboid, raising the scapula).

As mentioned above, a calm breath proceeds passively, almost against the background of relaxation of the muscles of inspiration. With active intensive exhalation, the muscles of the abdominal wall are “connected”, as a result of which the volume of the abdominal cavity decreases and the pressure in it increases. The pressure is transferred to the diaphragm and raises it. Due to the reduction the internal oblique intercostal muscles lower the ribs and bring their edges closer.

Breathing movements

In ordinary life, observing oneself and one's acquaintances, one can see both breathing, provided mainly by the diaphragm, and breathing, provided mainly by the work of the intercostal muscles. And this is within the normal range. The muscles of the shoulder girdle are more often connected with serious illnesses or intensive work, but almost never in relatively healthy people in a normal state.

It is believed that breathing, provided mainly by the movements of the diaphragm, is more typical for men. Normally, inhalation is accompanied by a slight protrusion of the abdominal wall, exhalation by its slight retraction. This is abdominal breathing.

In women, the chest type of breathing is most common, provided mainly by the work of the intercostal muscles. This may be due to the biological readiness of a woman for motherhood and, as a result, with difficulty in abdominal breathing during pregnancy. With this type of breathing, the most noticeable movements are made by the sternum and ribs.

Breathing, in which the shoulders and collarbones actively move, is provided by the work of the muscles of the shoulder girdle. Ventilation of the lungs in this case is ineffective and concerns only the tops of the lungs. Therefore, this type of breathing is called apical. Under normal conditions, this type of breathing practically does not occur and is used either during certain gymnastics or develops with serious diseases.

In freediving, we believe that abdominal or belly breathing is the most natural and productive type of breathing. The same is said in yoga and pranayama.

Firstly, because there are more alveoli in the lower lobes of the lungs. Secondly, respiratory movements are connected to our autonomic nervous system. Belly breathing activates the parasympathetic nervous system - the brake pedal for the body. Thoracic breathing activates the sympathetic nervous system - the gas pedal. With active and long apical breathing, restimulation of the sympathetic nervous system occurs. This works both ways. So panicking people always breathe apical breathing. And vice versa, if you breathe calmly with your stomach for some time, the nervous system calms down and all processes slow down.

lung volumes

During quiet breathing, a person inhales and exhales about 500 ml (from 300 to 800 ml) of air, this volume of air is called tidal volume. In addition to the usual tidal volume, with the deepest breath a person can inhale another approximately 3000 ml of air - this is inspiratory reserve volume. After a normal calm exhalation, an ordinary healthy person is able to “squeeze out” about 1300 ml of air from the lungs with the tension of the exhalation muscles - this is expiratory reserve volume.

The sum of these volumes is vital capacity (VC): 500 ml + 3000 ml + 1300 ml = 4800 ml.

As you can see, nature has prepared for us almost a tenfold supply of the possibility of "pumping" air through the lungs.

Tidal volume is a quantitative expression of the depth of breathing. The vital capacity of the lungs is the maximum volume of air that can be brought in or out of the lungs during one inhalation or exhalation. The average vital capacity of the lungs in men is 4000 - 5500 ml, in women - 3000 - 4500 ml. Physical training and various chest stretches can increase VC.

After maximum deep exhalation, about 1200 ml of air remains in the lungs. This - residual volume. Most of it can be removed from the lungs only with an open pneumothorax.

The residual volume is determined primarily by the elasticity of the diaphragm and intercostal muscles. Increasing the mobility of the chest and reducing the residual volume is an important task in preparing for diving to great depths. Dives below the residual volume for the average untrained person are dives deeper than 30-35 meters. One of the popular ways to increase the elasticity of the diaphragm and reduce the residual volume of the lungs is to regularly perform uddiyana bandha.

The maximum amount of air that can be in the lungs is called total lung capacity, it is equal to the sum of the residual volume and the vital capacity of the lungs (in the example used: 1200 ml + 4800 ml = 6000 ml).

The volume of air in the lungs at the end of a quiet exhalation (with relaxed respiratory muscles) is called functional residual lung capacity. It is equal to the sum of the residual volume and the expiratory reserve volume (in the example used: 1200 ml + 1300 ml = 2500 ml). Functional residual lung capacity is close to the volume of alveolar air before inhalation.

Lung ventilation is determined by the volume of air inhaled or exhaled per unit of time. Usually measured minute volume of breathing. Ventilation of the lungs depends on the depth and frequency of breathing, which at rest ranges from 12 to 18 breaths per minute. The minute volume of breathing is equal to the product of the respiratory volume and the respiratory rate, i.e. about 6-9 liters.

To assess lung volumes, spirometry is used - a method for studying the function of external respiration, which includes the measurement of volumetric and speed indicators of respiration. We recommend this study to anyone who plans to seriously engage in freediving.

Air is not only in the alveoli, but also in the airways. These include the nasal cavity (or mouth with oral breathing), nasopharynx, larynx, trachea, bronchi. The air in the airways (with the exception of the respiratory bronchioles) does not participate in gas exchange. Therefore, the lumen of the airways is called anatomical dead space. When inhaling, the last portions of atmospheric air enter the dead space and, without changing their composition, leave it when exhaling.

The volume of anatomical dead space is about 150 ml, or about 1/3 of the tidal volume during quiet breathing. Those. of 500 ml of inhaled air, only about 350 ml enters the alveoli. In the alveoli at the end of a calm exhalation there is about 2500 ml of air, therefore, with each calm breath, only 1/7 of the alveolar air is renewed.

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One of the main characteristics of external respiration is the minute volume of respiration (MOD). Lung ventilation is determined by the volume of air inhaled or exhaled per unit of time. MOD is the product of tidal volume times respiratory rate.. Normally, at rest, DO is 500 ml, the frequency of respiratory cycles is 12 - 16 per minute, hence the MOD is 6 - 7 l / min. Maximum ventilation of the lungs is the volume of air that passes through the lungs in 1 minute during the maximum frequency and depth of respiratory movements.

Alveolar ventilation

So, external respiration, or ventilation of the lungs, ensures that approximately 500 ml of air enters the lungs during each breath (DO). The saturation of the blood with oxygen and the removal of carbon dioxide occurs when contact of the blood of the pulmonary capillaries with the air contained in the alveoli. Alveolar air is the internal gas environment of the body of mammals and humans. Its parameters - the content of oxygen and carbon dioxide - are constant. The amount of alveolar air approximately corresponds to the functional residual capacity of the lungs - the amount of air that remains in the lungs after a quiet exhalation, and is normally 2500 ml. It is this alveolar air that is renewed by atmospheric air entering through the respiratory tract. It should be borne in mind that not all of the inhaled air is involved in pulmonary gas exchange, but only that part of it that reaches the alveoli. Therefore, to assess the effectiveness of pulmonary gas exchange, it is important not so much pulmonary ventilation as alveolar ventilation.

As you know, part of the tidal volume does not participate in gas exchange, filling the anatomically dead space of the respiratory tract - approximately 140 - 150 ml.

In addition, there are alveoli that are currently ventilated, but not supplied with blood. This part of the alveoli is the alveolar dead space. The sum of anatomical and alveolar dead spaces is called functional or physiological dead space. Approximately 1/3 of the respiratory volume falls on the ventilation of the dead space filled with air, which is not directly involved in gas exchange and only moves in the lumen of the airways during inhalation and exhalation. Therefore, ventilation of the alveolar spaces - alveolar ventilation - is pulmonary ventilation minus dead space ventilation. Normally, alveolar ventilation is 70 - 75% of the MOD value.

Calculation of alveolar ventilation is carried out according to the formula: MAV = (DO - MP)  BH, where MAV is minute alveolar ventilation, DO is tidal volume, MP is dead space volume, BH is respiratory rate.

Figure 6. Relationship between MOD and alveolar ventilation

We use these data to calculate another value characterizing alveolar ventilation - alveolar ventilation coefficient . This ratio shows how much of the alveolar air is renewed with each breath. In the alveoli at the end of a quiet exhalation there is about 2500 ml of air (FFU), during inspiration 350 ml of air enters the alveoli, therefore, only 1/7 of the alveolar air is renewed (2500/350 = 7/1).

Lung volumes and capacities

In the process of pulmonary ventilation, the gas composition of the alveolar air is continuously updated. The amount of pulmonary ventilation is determined by the depth of breathing, or tidal volume, and the frequency of respiratory movements. During respiratory movements, the lungs of a person are filled with inhaled air, the volume of which is part of the total volume of the lungs. To quantify lung ventilation, total lung capacity was divided into several components or volumes. In this case, the lung capacity is the sum of two or more volumes.

Lung volumes are divided into static and dynamic. Static lung volumes are measured with completed respiratory movements without limiting their speed. Dynamic lung volumes are measured during respiratory movements with a time limit for their implementation.

lung volumes. The volume of air in the lungs and respiratory tract depends on the following indicators: 1) anthropometric individual characteristics of a person and the respiratory system; 2) properties of lung tissue; 3) surface tension of the alveoli; 4) the force developed by the respiratory muscles.

Tidal volume (TO) The volume of air that a person inhales and exhales during quiet breathing. In an adult, DO is approximately 500 ml. The value of TO depends on the measurement conditions (rest, load, body position). DO is calculated as the average value after measuring approximately six quiet respiratory movements.

Inspiratory reserve volume (RIV)- the maximum volume of air that the subject can inhale after a quiet breath. The value of ROVD is 1.5-1.8 liters.

Expiratory reserve volume (ERV) is the maximum amount of air that a person can additionally exhale from the level of calm exhalation. The value of ROvyd is lower in the horizontal position than in the vertical position, and decreases with obesity. It is equal to an average of 1.0-1.4 liters.

Residual volume (RO) is the volume of air that remains in the lungs after maximum exhalation. The value of the residual volume is 1.0-1.5 liters.

The study of dynamic lung volumes is of scientific and clinical interest and their description is beyond the scope of the course of normal physiology.

Lung containers. Vital capacity (VC) includes tidal volume, inspiratory reserve volume, and expiratory reserve volume. In middle-aged men, VC varies within 3.5-5.0 liters or more. For women, lower values ​​are typical (3.0-4.0 l). Depending on the method of measuring VC, the VC of inhalation is distinguished, when the deepest breath is taken after a full exhalation and the VC of exhalation, when the maximum exhalation is made after a full breath.

The inspiratory capacity (Evd) is equal to the sum of the tidal volume and the inspiratory reserve volume. In humans, EUD averages 2.0-2.3 liters.

Functional residual capacity (FRC) - the volume of air in the lungs after a quiet exhalation. FRC is the sum of expiratory reserve volume and residual volume. FRC is measured by the methods of gas dilution, or dilution of gases, and plethysmographically. The FRC value is significantly affected by the level of physical activity of a person and the position of the body: FRC is less in a horizontal position of the body than in a sitting or standing position. FRC decreases with obesity due to a decrease in the overall compliance of the chest.

Total lung capacity (TLC) is the volume of air in the lungs at the end of a full breath. OEL is calculated in two ways: OEL - OO + VC or OEL - FOE + Evd. TRL can be measured using plethysmography or gas dilution.

Measurement of lung volumes and capacities is of clinical importance in the study of lung function in healthy individuals and in the diagnosis of human lung disease. The measurement of lung volumes and capacities is usually performed by spirometry, pneumotachometry with the integration of indicators and body plethysmography. Static lung volumes may decrease in pathological conditions leading to limited expansion of the lungs. These include neuromuscular diseases, diseases of the chest, abdomen, pleural lesions that increase the rigidity of the lung tissue, and diseases that cause a decrease in the number of functioning alveoli (atelectasis, resection, cicatricial changes in the lungs).

For comparability of the results of measurements of gas volumes and capacities, the data obtained must be correlated with conditions in the lungs, where the temperature of the alveolar air corresponds to body temperature, the air is at a certain pressure and is saturated with water vapor. This state is called the standard state and is denoted by the letters BTPS (body temperature, pressure, saturated).