Vital capacity is defined as
- A. the air left in the lungs after the deepest possible expiration
- B. the volume of one quiet breath
- C. the volume of air in the dead space
- D. the maximum volume of air that can be expelled after the deepest possible inspiration
Explanation
Vital capacity is the sum of the tidal volume and the inspiratory and expiratory reserve volumes, so it measures the usable range of the lungs and falls in diseases such as emphysema and fibrosis. The air remaining after the fullest expiration is the residual volume, about 1,200 cm3, which cannot be expelled and keeps the alveoli from collapsing. Total lung capacity is vital capacity plus residual volume.
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