Lung capacity , or pulmonary capacity, is the volume of air passing through the lungs during various phases of the respiratory cycle .
The lung volume can be measured directly: this is the amount of air inhaled after a deep exhalation. The average capacity of a light adult male can be up to 6 liters of air, usually 3-4 liters, but only a small part of this volume is used during normal breathing. The normal tidal volume is the volume of air passing through the lung during a calm inhalation and calm exhalation. The average person takes 16-20 breaths per minute.
Factors Affecting Lung Volume
Various factors can affect lung capacity:
| Large volumes | Small volumes |
|---|---|
| tall people | low people |
| non-smokers | smokers |
| living high above sea level | living at sea level |
| asthenics | hypersthenics |
| male | female |
| elderly age |
People living at sea level have less lung capacity than people living at high altitude. This is due to the fact that atmospheric pressure is less at high altitude, as a result, diffusion of oxygen into the blood is difficult. The body, adapting to this situation, increases the oxygen conductivity of tissues.
Therefore, people living usually at an altitude close to sea level develop altitude sickness , getting high in the mountains or at a great height. This is due to the fact that the lungs exhale a sufficient amount of carbon dioxide , but cannot extract enough oxygen. In a healthy person, the level of carbon dioxide is a factor regulating the respiratory process.
Changes in lung volume occur during pregnancy . The decrease in lung capacity from 1.7 to 1.35 L is due to the pressure of the uterus on the diaphragm . Uterine pressure also leads to a decrease in the total lung capacity by 5% and a decrease in the reserve volume of exhaled gas. The normal volume of inhaled air increases by 30-40%, from 0.45 to 0.65 liters, the ventilation rate increases by 30-40%. This process is necessary to increase the amount of inhaled oxygen, since the body needs 50 ml of oxygen per minute, 20 ml of which is necessary for developing tissues. As a result of the interaction of these processes, the total respiratory capacity does not change.
See also
- Spirometry