Why might there be some variation in the tidal volume and vital capacity of different people?
Tidal volume and vital capacity are two different things. The tidal volume of a person is usually measured at 10cc/kg of body weight. Therefore, if you weigh 78 kg, you would get a 780 cc tidal volume. Vital capacity is the maximum amount of air that can be exhaled after a maximum inhalation (usually tested with a spirometer). It is used to determine the condition of lung tissue. Reasons for variations in different people, their age, size, disease process. Like, for instance, if you have scoliosis, your vital capacity is going to be smaller because your lungs are being compromised.
