Define vital capacity. What is its significance?

Vital capacity is the maximum volume of air that can be exhaled after a maximum inspiration. It is about 3.5 – 4.5 liters in the human body.

It allows the intake of the maximum amount of fresh air along with getting rid of the foul air in a single stroke of respiration. Hence, it increases the gaseous exchange between the various tissues of the body, this leads to the increased amount of energy available for body functioning.