Transcript
SPEAKER
Lung capacity is calculated from the volume of air that is exchanged during normal and forceful breathing. Resting tidal volume refers to the amount of air entering or leaving the lungs in a single normal breath, and is about half a litre in adults.
If you take a deep breath in, the extra volume of air inspired is called the inspiratory reserve volume. Likewise, if you breathe out for as long as you can after a normal intake of breath, the extra volume breathed out is the expiratory reserve volume.
The average inspiratory volume for an adult is about 2 to 3 litres, while the expiratory reserve volume is about 1 litre. There is always a small amount of air left in the lungs in addition to the expiratory reserve volume. And this is known as the residual volume.
Vital capacity is the sum of the tidal, inspiratory and expiratory volumes. Total lung capacity is the sum of all the volumes, including the residual volume. Total lung capacity represents the maximum amount of air that the lungs can hold.