Lung volume is the percentage of air that lungs can hold at any given period of time. This differs from person to person. The physical differences that accompany lung volume are known as lung volumes. There is also something very similar to this called lung capacity, which are the variety of combinations that lung volumes can take on. This has to do with the inhaling and exhaling of air into and out of the lungs.
On average, a human being can retain 6.3 quarts (6 liters) of air in his lungs at any one time. The capacity of the lungs that is needed for regular breathing uses a very small proportion of this, however. Every minute, an average person breathes anywhere from nine to 20 times.
The type of breathing done by humans, as well as all types of mammals, is known as tidal breathing. What this means is that when air is breathed into the body, it enters the lungs in the same manner as it exits the lungs. Sometimes it is described as tidal volume (TV). Another aspect that is important to this is the fact that there is no conscious effort involved in breathing for all mammals. Breathing is involuntary.
Lung volume measurements can be used as an instrument for study. They provide valuable information into how the lungs work. Lung volume can also be beneficial in terms of evaluating respiratory diseases.
There are a few terms connected to lung volume that are important to be aware of. Vital capacity (VC) is the total amount of air that is able to be exhaled following an inhalation. There is never a point at which the lungs contain no air whatsoever; to be alive, mammals must have air circulating to and from the lungs. Residual volume (RV) is the air volume that remains in the lung after a complete exhalation has taken place. VC and RV are added together to provide total lung capacity (TLC).
Lung volume can be affected by a variety of factors. Some of these can be controlled voluntarily, while others are not within the control of the individual. People who tend to have larger lung volumes include males, taller individuals, athletes, non-smokers, and those living at high altitudes. On the other side, those with smaller lung volumes often include females, shorter individuals, non-athletes, smokers, and those residing in areas of low altitudes.