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Determination of minute volume of respiration physiology. Minute breathing volume

UDC 612.215+612.1 BBK E 92 + E 911

A.B. Zagainova, N.V. Turbasova. Physiology of respiration and blood circulation. Educational and methodological manual for the course “Physiology of Humans and Animals”: for 3rd year ODO and 5th year ODO students of the Faculty of Biology. Tyumen: Tyumen Publishing House state university, 2007. - 76 p.

The educational manual includes laboratory works, compiled in accordance with the course program “Physiology of Humans and Animals”, many of which illustrate the fundamental scientific principles of classical physiology. Some of the work is of an applied nature and represents methods of self-monitoring of health and physical condition, methods for assessing physical performance.

EDITOR IN CHARGE: V.S. Soloviev , Doctor of Medical Sciences, Professor

Explanatory note

The subject of research in the sections “respiration” and “blood circulation” are living organisms and their functioning structures that provide these vital functions, which determines the choice of methods of physiological research.

The purpose of the course: to form ideas about the mechanisms of functioning of the respiratory and circulatory organs, about the regulation of the activity of the cardiovascular and respiratory systems, about their role in ensuring the interaction of the body with the external environment.

Objectives of the laboratory workshop: to familiarize students with research methods physiological functions humans and animals; illustrate fundamental scientific principles; present methods of self-monitoring of physical condition, assessment of physical performance during physical activity of varying intensity.

To conduct laboratory classes in the course “Human and Animal Physiology”, 52 hours are allocated for ODO and 20 hours for ODO. The final reporting form for the course “Human and Animal Physiology” is an exam.

Requirements for the exam: it is necessary to understand the basics of the body’s vital functions, including the mechanisms of functioning of organ systems, cells and individual cellular structures, regulation of work physiological systems, as well as patterns of interaction of the organism with the external environment.

The educational and methodological manual was developed as part of the general course program “Physiology of Humans and Animals” for students of the Faculty of Biology.

PHYSIOLOGY OF BREATHING

The essence of the breathing process is the delivery of oxygen to the tissues of the body, which ensures the occurrence of oxidative reactions, which leads to the release of energy and the release of carbon dioxide from the body, which is formed as a result of metabolism.

A process that occurs in the lungs and involves the exchange of gases between the blood and environment(air entering the alveoli is called external, pulmonary breathing, or ventilation.

As a result of gas exchange in the lungs, the blood is saturated with oxygen and loses carbon dioxide, i.e. again becomes capable of transporting oxygen to tissues.

Gas Composition Update internal environment the body occurs due to blood circulation. The transport function is carried out by blood due to the physical dissolution of CO 2 and O 2 in it and their binding to blood components. Thus, hemoglobin is able to enter into a reversible reaction with oxygen, and the binding of CO 2 occurs as a result of the formation of reversible bicarbonate compounds in the blood plasma.

The consumption of oxygen by cells and the implementation of oxidative reactions with the formation of carbon dioxide is the essence of the processes internal, or tissue respiration.

Thus, only sequential study All three parts of breathing can give an idea of one of the most complex physiological processes.

For studying external respiration(pulmonary ventilation), gas exchange in the lungs and tissues, as well as gas transport in the blood are used various methods, allowing the assessment of respiratory function at rest, with physical activity and various effects on the body.

LABORATORY WORK No. 1

PNEUMOGRAPHY

Pneumography is a registration breathing movements. It allows you to determine the frequency and depth of breathing, as well as the ratio of the duration of inhalation and exhalation. In an adult, the number of respiratory movements is 12-18 per minute; in children, breathing is more frequent. At physical work it doubles or more. During muscular work, both the frequency and depth of breathing changes. Changes in the rhythm of breathing and its depth are observed during swallowing, talking, after holding the breath, etc.

There are no pauses between the two phases of breathing: inhalation directly turns into exhalation and exhalation into inhalation.

As a rule, the inhalation is slightly shorter than the exhalation. The time of inhalation is related to the time of exhalation, like 11:12 or even like 10:14.

In addition to rhythmic respiratory movements that provide ventilation of the lungs, special respiratory movements may be observed over time. Some of them arise reflexively (protective respiratory movements: coughing, sneezing), others voluntarily, in connection with phonation (speech, singing, recitation, etc.).

Registration of respiratory movements chest carried out using a special device - a pneumograph. The resulting record - a pneumogram - allows you to judge: the duration of the breathing phases - inhalation and exhalation, breathing frequency, relative depth, dependence of the frequency and depth of breathing on physiological state body - rest, work, etc.

Pneumography is based on the principle of air transmission of respiratory movements of the chest to a writing lever.

The most commonly used pneumograph at present is an oblong rubber chamber placed in a fabric cover, hermetically connected by a rubber tube to the Marais capsule. With each inhalation, the chest expands and compresses the air in the pneumograph. This pressure is transmitted into the cavity of the Marais capsule, its elastic rubber cap rises, and the lever resting on it writes a pneumogram.

Depending on the sensors used, pneumography can be performed different ways. The simplest and most accessible for recording respiratory movements is a pneumatic sensor with a Marais capsule. For pneumography, rheostat, strain gauge and capacitive sensors can be used, but in this case electronic amplifying and recording devices are required.

To work you need: kymograph, sphygmomanometer cuff, Marais capsule, tripod, tee, rubber tubes, timer, ammonia solution. The object of research is a person.

Carrying out work. Assemble the installation for recording respiratory movements, as shown in Fig. 1, A. The cuff from the sphygmomanometer is fixed on the most mobile part of the subject’s chest (for abdominal breathing this will be the lower third, for chest breathing - the middle third of the chest) and is connected using a tee and rubber tubes to the Marais capsule. Through the tee, opening the clamp, a small amount of air is introduced into the recording system, making sure that too much high pressure the rubber membrane of the capsule did not rupture. After making sure that the pneumograph is strengthened correctly and the movements of the chest are transmitted to the lever of the Marais capsule, count the number of respiratory movements per minute, and then set the scribe tangentially to the kymograph. Turn on the kymograph and timer and begin recording the pneumogram (the subject should not look at the pneumogram).

Rice. 1. Pneumography.

A - graphic recording of breathing using the Marais capsule; B - pneumograms recorded during action various factors causing changes in breathing: 1 - wide cuff; 2 - rubber tube; 3 – tee; 4 - Marais capsule; 5 – kymograph; 6 - time counter; 7 - universal tripod; a - calm breathing; b - when inhaling ammonia vapor; c - during a conversation; d - after hyperventilation; d - after voluntary holding of breath; e - during physical activity; b"-e" - marks of the applied influence.

The following types of breathing are recorded on a kymograph:

1) calm breathing;

2) deep breathing (the subject voluntarily takes several deep breaths and exhalations - the vital capacity of the lungs);

3) breathing after physical activity. To do this, the subject is asked, without removing the pneumograph, to do 10-12 squats. At the same time, so that as a result of sharp shocks of air the tire of the Marey capsule does not rupture, a Pean clamp is used to compress the rubber tube connecting the pneumograph to the capsule. Immediately after finishing the squats, the clamp is removed and breathing movements are recorded);

4) breathing during recitation, colloquial speech, laughter (pay attention to how the duration of inhalation and exhalation changes);

5) breathing when coughing. To do this, the subject makes several voluntary exhaling cough movements;

6) shortness of breath - dyspnea caused by holding your breath. The experiment is carried out in the following order. After recording normal breathing (eipnea) with the subject sitting, ask him to hold his breath as he exhales. Usually, after 20-30 seconds, involuntary restoration of breathing occurs, and the frequency and depth of respiratory movements become significantly greater, and shortness of breath is observed;

7) a change in breathing with a decrease in carbon dioxide in the alveolar air and blood, which is achieved by hyperventilation of the lungs. The subject makes deep and frequent breathing movements until he feels slightly dizzy, after which a natural breath hold occurs (apnea);

8) when swallowing;

9) when inhaling ammonia vapor (cotton moistened with ammonia solution is brought to the test subject’s nose).

Some pneumograms are shown in Fig. 1,B.

Paste the resulting pneumograms into your notebook. Calculate the number of respiratory movements in 1 minute at different conditions pneumogram registration. Determine in what phase of breathing swallowing and speech occur. Compare the nature of changes in breathing under the influence of various exposure factors.

LABORATORY WORK No. 2

SPIROMETRY

Spirometry is a method for determining the vital capacity of the lungs and its constituent air volumes. Vital capacity lungs (VC) is the largest amount of air that a person can exhale after a maximum inhalation. In Fig. Figure 2 shows lung volumes and capacities characterizing the functional state of the lungs, as well as a pneumogram explaining the connection between lung volumes and capacities and respiratory movements. Functional status lungs depends on age, height, gender, physical development and a number of other factors. To assess respiratory function in a given person, measured lung volumes should be compared with appropriate values. Proper values are calculated using formulas or determined using nomograms (Fig. 3); deviations of ± 15% are regarded as insignificant. To measure vital capacity and its component volumes, a dry spirometer is used (Fig. 4).

Rice. 2. Spirogram. Lung volumes and capacities:

ROVD - inspiratory reserve volume; DO - tidal volume; ROvyd - expiratory reserve volume; OO - residual volume; Evd - inspiratory capacity; FRC - functional residual capacity; Vital capacity - vital capacity of the lungs; TLC - total lung capacity.

Lung volumes:

Inspiratory reserve volume(ROVD) - the maximum volume of air that a person can inhale after a quiet breath.

Expiratory reserve volume(ROvyd) - the maximum volume of air that a person can exhale after a quiet exhalation.

Residual volume(OO) is the volume of gas in the lungs after maximum exhalation.

Inspiratory capacity(Evd) is the maximum volume of air that a person can inhale after a quiet exhalation.

Functional residual capacity(FRC) is the volume of gas remaining in the lungs after a quiet inhalation.

Vital capacity of the lungs(VC) – the maximum volume of air that can be exhaled after a maximum inhalation.

Total lung capacity(Oel) - the volume of gases in the lungs after maximum inspiration.

To work you need: dry spirometer, nose clip, mouthpiece, alcohol, cotton wool. The object of research is a person.

The advantage of a dry spirometer is that it is portable and easy to use. A dry spirometer is an air turbine rotated by a stream of exhaled air. The rotation of the turbine is transmitted through a kinematic chain to the arrow of the device. To stop the needle at the end of exhalation, the spirometer is equipped with a braking device. The measured volume of air is determined using the scale of the device. The scale can be rotated, allowing the pointer to be reset to zero before each measurement. Air is exhaled from the lungs through a mouthpiece.

Carrying out work. The spirometer mouthpiece is wiped with cotton wool moistened with alcohol. After a maximum inhalation, the subject exhales as deeply as possible into the spirometer. Vital vital capacity is determined using the spirometer scale. The accuracy of the results increases if vital capacity is measured several times and the average value is calculated. For repeated measurements, it is necessary to set the initial position of the spirometer scale each time. To do this, the measuring scale of a dry spirometer is turned and the zero division of the scale is aligned with the arrow.

Vital vital capacity is determined with the subject standing, sitting and lying down, as well as after physical activity (20 squats in 30 seconds). Note the difference in the measurement results.

Then the subject takes several quiet exhalations into the spirometer. At the same time, the number of respiratory movements is counted. By dividing the spirometer readings by the number of exhalations made into the spirometer, determine tidal volume air.

Rice. 3. Nomogram for determining the proper value of vital capacity.

Rice. 4. Dry air spirometer.

For determining expiratory reserve volume After the next quiet exhalation, the subject exhales maximally into the spirometer. The expiratory reserve volume is determined using the spirometer scale. Repeat the measurements several times and calculate the average value.

Inspiratory reserve volume can be determined in two ways: calculated and measured with a spirometer. To calculate it, it is necessary to subtract the sum of the respiratory and reserve (exhalation) air volumes from the vital capacity value. When measuring the inspiratory reserve volume with a spirometer, a certain volume of air is drawn into it and the subject, after a quiet inhalation, takes a maximum breath from the spirometer. The difference between the initial volume of air in the spirometer and the volume remaining there after a deep inspiration corresponds to the inspiratory reserve volume.

For determining residual volume air there are no direct methods, so indirect ones are used. They can be based on different principles. For these purposes, for example, plethysmography, oxygemometry and measurement of the concentration of indicator gases (helium, nitrogen) are used. It is believed that normally the residual volume is 25-30% of the vital capacity.

The spirometer makes it possible to establish a number of other characteristics of respiratory activity. One of them is the amount of pulmonary ventilation. To determine it, the number of respiratory cycles per minute is multiplied by the tidal volume. Thus, in one minute about 6000 ml of air is normally exchanged between the body and the environment.

Alveolar ventilation= respiratory rate x (tidal volume - volume of “dead” space).

By establishing breathing parameters, you can assess the intensity of metabolism in the body by determining oxygen consumption.

During the work, it is important to find out whether the values obtained for a particular person are within the normal range. For this purpose, special nomograms and formulas have been developed that take into account the correlation individual characteristics functions of external respiration and factors such as gender, height, age, etc.

The proper value of the vital capacity of the lungs is calculated using the formulas (Guminsky A.A., Leontyeva N.N., Marinova K.V., 1990):

for men -

VC = ((height (cm) x 0.052) – (age (years) x 0.022)) - 3.60;

for women -

VC = ((height (cm) x 0.041) - (age (years) x 0.018)) - 2.68.

for boys 8 -12 years old -

VC = ((height (cm) x 0.052) - (age (years) x 0.022)) - 4.6;

for boys 13 -16 years old-

VC = ((height (cm) x 0.052) - (age (years) x 0.022)) - 4.2;

for girls 8 - 16 years old -

VC = ((height (cm) x 0.041) - (age (years) x 0.018)) - 3.7.

By the age of 16-17 years, the vital capacity of the lungs reaches values characteristic of an adult.

Results of the work and their design. 1. Enter the measurement results in Table 1 and calculate the average vital value.

Table 1

Measurement number	Vital vital capacity (rest)
Measurement number	standing	sitting
1 2 3 Average

2. Compare the results of measurements of vital capacity (rest) while standing and sitting. 3. Compare the results of measurements of vital capacity while standing (at rest) with the results obtained after physical activity. 4. Calculate the % of the proper value, knowing the vital capacity indicator obtained by measuring standing (rest) and the proper vital capacity (calculated by the formula):

GELfact. x 100 (%).

5. Compare the VC value measured by the spirometer with the proper VC found using the nomogram. Calculate residual volume as well as lung capacities: total lung capacity, inspiratory capacity, and functional residual capacity. 6. Draw conclusions.

LABORATORY WORK No. 3

DETERMINATION OF MINUTE VOLUME OF RESPIRATION (MOV) AND PULMONARY VOLUME

(TIDATORY, INSPIRATIONAL RESERVE VOLUME

AND EXPIRATORAL RESERVE VOLUME)

Ventilation is determined by the volume of air inhaled or exhaled per unit of time. Minute volume of respiration (MRV) is usually measured. Its value during quiet breathing is 6-9 liters. Ventilation of the lungs depends on the depth and frequency of breathing, which at rest is 16 per 1 minute (from 12 to 18). The minute volume of breathing is equal to:

MOD = TO x BH,

where DO - tidal volume; RR - respiratory rate.

To work you need: dry spirometer, nose clip, alcohol, cotton wool. The object of research is a person.

Carrying out work. To determine the volume of respiratory air, the test subject must exhale calmly into the spirometer after a calm inhalation and determine the tidal volume (TI). To determine the expiratory reserve volume (ERV), after a calm, normal exhalation into the surrounding space, exhale deeply into the spirometer. To determine the inspiratory reserve volume (IRV), set the internal cylinder of the spirometer at some level (3000-5000), and then, taking a calm breath from the atmosphere, holding your nose, take a maximum breath from the spirometer. Repeat all measurements three times. The inspiratory reserve volume can be determined by the difference:

ROVD = VITAL - (DO - ROvyd)

Using the calculation method, determine the sum of DO, ROvd and ROvd, which makes up the vital capacity of the lungs (VC).

Results of the work and their design. 1. Present the obtained data in the form of table 2.

2. Calculate the minute volume of breathing.

table 2

LABORATORY WORK No. 4

To assess the quality of lung function, it examines tidal volumes (using special devices - spirometers).

Tidal volume (TV) is the amount of air that a person inhales and exhales during quiet breathing in one cycle. Normal = 400-500 ml.

Minute respiration volume (MRV) is the volume of air passing through the lungs in 1 minute (MRV = DO x RR). Normal = 8-9 liters per minute; about 500 l per hour; 12000-13000 liters per day. With increasing physical activity, MOD increases.

Not all inhaled air participates in alveolar ventilation (gas exchange), because part of it does not reach the acini and remains in respiratory tract where there is no opportunity for diffusion. The volume of such airways is called “respiratory dead space”. Normally for an adult = 140-150 ml, i.e. 1/3 TO.

Inspiratory reserve volume (IRV) is the amount of air that a person can inhale during the strongest maximum inhalation after a quiet inhalation, i.e. over DO. Normal = 1500-3000 ml.

Expiratory reserve volume (ERV) is the amount of air that a person can additionally exhale after a quiet exhalation. Normal = 700-1000 ml.

Vital capacity of the lungs (VC) is the amount of air that a person can maximally exhale after the deepest inhalation (VC=DO+ROVd+ROVd = 3500-4500 ml).

Residual lung volume (RLV) is the amount of air remaining in the lungs after maximum exhalation. Normal = 100-1500 ml.

Total lung capacity (TLC) is the maximum amount of air that can be held in the lungs. TEL=VEL+TOL = 4500-6000 ml.

DIFFUSION OF GASES

Composition of inhaled air: oxygen - 21%, carbon dioxide - 0.03%.

Composition of exhaled air: oxygen - 17%, carbon dioxide - 4%.

The composition of the air contained in the alveoli: oxygen - 14%, carbon dioxide -5.6%.

As you exhale, the alveolar air is mixed with the air in the respiratory tract (in the “dead space”), which causes the indicated difference in air composition.

The transition of gases through the air-hematic barrier is due to the difference in concentrations on both sides of the membrane.

Partial pressure is that part of the pressure that falls on a given gas. At an atmospheric pressure of 760 mm Hg, the partial pressure of oxygen is 160 mm Hg. (i.e. 21% of 760), in the alveolar air the partial pressure of oxygen is 100 mm Hg, and carbon dioxide is 40 mm Hg.

Gas voltage is the partial pressure in a liquid. Oxygen tension in venous blood is 40 mm Hg. Due to the pressure gradient between alveolar air and blood - 60 mm Hg. (100 mm Hg and 40 mm Hg), oxygen diffuses into the blood, where it binds to hemoglobin, converting it into oxyhemoglobin. Blood containing a large amount of oxyhemoglobin is called arterial. 100 ml of arterial blood contains 20 ml of oxygen, 100 ml of venous blood contains 13-15 ml of oxygen. Also, along the pressure gradient, carbon dioxide enters the blood (since it is contained in large quantities in the tissues) and carbhemoglobin is formed. In addition, carbon dioxide reacts with water, forming carbonic acid (the reaction catalyst is the enzyme carbonic anhydrase, found in red blood cells), which breaks down into a hydrogen proton and bicarbonate ion. CO 2 tension in venous blood is 46 mm Hg; in alveolar air – 40 mm Hg. (pressure gradient = 6 mmHg). Diffusion of CO 2 occurs from the blood into the external environment.

One of the main methods for assessing the ventilation function of the lungs used in the practice of medical labor examination is spirography, which allows you to determine statistical pulmonary volumes - vital capacity of the lungs (VC), functional residual capacity (FRC), residual lung volume, total lung capacity, dynamic pulmonary volumes - tidal volume, minute volume, maximum ventilation.

The ability to fully maintain the gas composition of arterial blood does not yet guarantee the absence of pulmonary failure in patients with bronchopulmonary pathology. Blood arterialization can be maintained at a level close to normal due to compensatory overstrain of the mechanisms that provide it, which is also a sign of pulmonary failure. Such mechanisms include, first of all, the function ventilation.

The adequacy of volumetric ventilation parameters is determined by “ dynamic lung volumes", which include tidal volume And minute volume of respiration (MOV).

Tidal volume at rest healthy person is about 0.5 l. Due MAUD obtained by multiplying the required basal metabolic rate by a factor of 4.73. The values obtained in this way lie in the range of 6-9 l. However, comparison of the actual value MAUD(determined under the conditions of the basal metabolic rate or close to it) properly makes sense only for a summary assessment of changes in value, which may include both changes in ventilation itself and disturbances in oxygen consumption.

To assess the actual ventilation deviations from the norm, it is necessary to take into account Oxygen utilization factor (KIO 2)- ratio of absorbed O 2 (in ml/min) to MAUD(in l/min).

Based oxygen utilization factor the effectiveness of ventilation can be judged. In healthy people, the CI is on average 40.

At KIO 2 below 35 ml/l ventilation is excessive in relation to the oxygen consumed ( hyperventilation), with increasing KIO 2 above 45 ml/l we are talking about hypoventilation.

Another way of expressing the gas exchange efficiency of pulmonary ventilation is by defining respiratory equivalent, i.e. the volume of ventilated air per 100 ml of oxygen consumed: determine the ratio MAUD to the amount of oxygen consumed (or carbon dioxide - DE carbon dioxide).

In a healthy person, 100 ml of oxygen consumed or carbon dioxide released is provided by a volume of ventilated air close to 3 l/min.

In patients with lung pathology functional disorders gas exchange efficiency is reduced, and the consumption of 100 ml of oxygen requires more ventilation than in healthy people.

When assessing the effectiveness of ventilation, an increase breathing rate(BH) is considered as typical sign respiratory failure, it is advisable to take this into account during a labor examination: with degree I of respiratory failure, the respiratory rate does not exceed 24, with degree II it reaches 28, with III degree The black hole is very large.

Medical rehabilitation / Ed. V. M. Bogolyubova. Book I. - M., 2010. pp. 39-40.

Ventilation is a continuous, controlled process of updating the gas composition of the air contained in the lungs. Ventilation of the lungs is ensured by introducing into them atmospheric air, rich in oxygen, and excreting gas containing excess carbon dioxide during exhalation.

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

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

Static indicators include four primary pulmonary volumes: - tidal volume (VT - VT);

Inspiratory reserve volume (IRV);

Expiratory reserve volume (ERV);

Residual volume (RO - RV).

And also containers:

Vital capacity of the lungs (VC - VC);

Inspiratory capacity (Evd - IC);

Functional residual capacity (FRC - FRC);

Total lung capacity (TLC).

Dynamic quantities characterize volumetric velocity air flow. They are determined taking into account the time spent performing the breathing maneuver. Dynamic indicators include:

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

Forced vital capacity (FVC - FVC);

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

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

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

2) elastic properties lung tissue and respiratory tract;

3) contractile characteristics of inspiratory and expiratory muscles.

To determine pulmonary volumes and capacities, the methods of spirometry, spirography, pneumotachometry and body plethysmography are used.

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

Tidal volume

Tidal volume (TV) 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).

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

Expiratory reserve volume

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

Inspiratory reserve volume

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

Vital capacity of the lungs

Vital capacity of the lungs (VC) is the maximum amount of air exhaled after the deepest inhalation. Vital vital capacity is one of the main indicators of the condition 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, vital capacity forms the total lung capacity (TLC).

Normally, vital capacity 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. During quiet breathing, a healthy adult uses a small part of vital capacity: inhales and exhales 300-500 ml of air (the so-called tidal volume). In this case, the inspiratory reserve volume, i.e. the amount of air that a person is able to additionally inhale after a quiet inhalation, and the reserve volume of exhalation, equal to the volume of additionally exhaled air after a quiet exhalation, averages approximately 1500 ml each. During physical activity, tidal volume increases due to the use of inhalation and exhalation reserves.

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

From a practical point of view, it is inappropriate to establish a “single” standard 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 on average 25% less than men.

The relationship with height can be calculated using the following equation:

VC=2.5*height (m)

Vital capacity depends on the position of the body: in a vertical position it is slightly greater than in a horizontal position.

This is explained by the fact that in vertical position the lungs contain less blood. In trained people (especially swimmers and rowers) it can be up to 8 l, 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 to 1000 - 1500 ml.

Total lung capacity

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

A study of tidal volumes is necessary to assess compensation for 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 starting swimming or running, the vital capacity of young athletes’ lungs can increase by 500 cc. and more. A decrease in it 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 stopper and disinfect its mouthpiece with alcohol. After taking a deep breath, exhale deeply through the mouthpiece. In this case, air should not pass past 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. A decrease of more than 300 cc may indicate overwork.

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

Tidal volume and vital capacity are static characteristics measured during one respiratory cycle. But oxygen consumption and carbon dioxide formation occur continuously in the body.

Therefore, the constancy of the gas composition of arterial blood does not depend on the characteristics of one respiratory cycle, but on the rate of oxygen intake and carbon dioxide removal over a long period of time. A measure of this speed, to some extent, can be considered the minute volume of respiration (MVR), or pulmonary ventilation, i.e. the volume of air passing through the lungs in 1 minute. The minute volume of breathing with uniform automatic (without the participation of consciousness) breathing is equal to the product of the tidal volume by the number of respiratory cycles in 1 minute. At rest in a man, it is on average 8000 ml or 8 liters per minute)" (500 ml x 16 breaths per minute). It is believed that the minute volume of breathing provides information about ventilation of the lungs, but in no way determines the efficiency of breathing. With a tidal volume of 500 ml, the alveoli during inspiration first receive 150 ml of air located in the respiratory tract, i.e., in the anatomical dead space, and entered them at the end of the previous exhalation. This is already used air that entered the anatomical dead space from alveoli. Thus, when you inhale 500 ml of “fresh” air from the atmosphere, 350 ml enters the alveoli from them. The last 150 ml of inhaled “fresh” air fills the anatomical dead space and does not participate in gas exchange with the blood. As a result, in 1 minute)" with a tidal volume of 500 ml and 16 breaths in the first minute, not 8 liters of atmospheric air will pass through the alveoli, but 5.6 liters (350 x 16 = 5600), the so-called alveolar ventilation. When the tidal volume is reduced to 400 ml, in order to maintain the same value of the minute volume of breathing, the respiratory rate should increase to 20 breaths per 1 minute (8000: 400). In this case, alveolar ventilation will be 5000 ml (250 x 20) instead of 5600 ml, which are necessary to maintain a constant gas composition of arterial blood. To maintain arterial blood gas homeostasis, it is necessary to increase the respiratory rate to 22-23 breaths per minute (5600: 250-22.4). This implies an increase in minute respiratory volume to 8960 ml (400 x 22.4). With a tidal volume of 300 ml, to maintain alveolar ventilation and, accordingly, blood gas homeostasis, the respiratory rate should increase to 37 breaths per minute (5600: 150 = 37.3). In this case, the minute volume of breathing will be 11100 ml (300 x 37 = 11100), i.e. will increase almost 1.5 times. Thus, the minute volume of breathing in itself does not determine the effectiveness of breathing.
A person can take control of breathing upon himself and, at will, breathe with his stomach or chest, change the frequency and depth of breathing, the duration of inhalation and exhalation, etc. However, no matter how he changes his breathing, in a state of physical rest the amount of atmospheric air , entering the alveoli in 1 minute)", should remain approximately the same, namely, 5600 ml, to ensure normal blood gas composition,
the needs of cells and tissues for oxygen and for the removal of excess carbon dioxide. If you deviate from this value in any direction, the gas composition of arterial blood changes. The homeostatic mechanisms of its maintenance are immediately activated. They come into conflict with the deliberately formed overestimated or underestimated value of alveolar ventilation. In this case, the feeling of comfortable breathing disappears, and either a feeling of lack of air or a feeling of muscle tension. Thus, maintaining a normal blood gas composition while deepening breathing, i.e. with an increase in tidal volume, it is possible only by decreasing the frequency of respiratory cycles, and, conversely, with an increase in respiratory frequency, maintaining gas homeostasis is possible only with a simultaneous decrease in tidal volume.
In addition to the minute volume of breathing, there is also the concept of maximum pulmonary ventilation (MVL) - the volume of air that can pass through the lungs in 1 minute at maximum ventilation. In an untrained adult male, maximum ventilation during physical activity can exceed the minute volume of breathing at rest by 5 times. In trained people, maximum ventilation of the lungs can reach 120 liters, i.e. minute breathing volume can increase 15 times. With maximum ventilation of the lungs, the ratio of tidal volume and respiratory rate is also significant. With the same value of maximum ventilation of the lungs, alveolar ventilation will be higher at a lower respiratory rate and, accordingly, at a larger tidal volume. As a result, in arterial blood During the same time, more oxygen can enter and more carbon dioxide can leave.