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Lung Volumes
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Lung volume (litres)
BSY &
Time
A - Tidal volume (0.5 litre); normal quiet breathing B - Vital capacity (5 litres); maximum inhalation and exhalation C - Inhalation reserve (3 litres) D - Exhalation reserve (1 litres) E - Residual volume (1.2 litres) F - Resting exhalation level (2.2 litres)
The volume of air that moves into and out of the alveoli per minute is called alveolar ventilation. It is equal to the tidal volume minus the dead space, multiplied by the respiratory rate: (TV - dead space) X respiratory rate = (500-150) ml x 15 per minute = 5.25 litres per minute. All the above values are typical for a young adult male. The volumes are about 25 percent less for an average female, and vary with body size, posture and physical condition. Lung function tests carried out to diagnose and monitor respiratory disorders are based on the parameters above.
If the lungs are not developed properly or are damaged, their volume and capacity is reduced and they cannot perform the function of oxygenating the blood in an efficient manner. Lung volumes can be increased by the practices of pranayama and deep breathing exercises. Lungs which have a good reserve capacity will turn out extra work when extra demand is made on them. It must also be taken into account that the distribution of blood in the lungs is gravity-dependent, and in the upright position there is far more blood in the lower
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