Breathing and Exchange of Gases – Solutions

1. Define vital capacity. What is its significance?

Solution:

Vital capacity is the maximum amount of air that a person can expel from the lungs after first filling them to their maximum capacity and then expiring to the maximum extent. It equals the inspiratory reserve volume plus the tidal volume plus the expiratory reserve volume. It is about 3.5 to 4.5 litres in the human body. It enables a person to get fresh air or oxygen and to get rid of carbon dioxide, thereby increasing the gaseous exchange between the tissues and the environment.

2. State the volume of air remaining in the lungs after a normal breathing.

Solution:

The volume of air that remains in the lungs after normal breathing is known as Functional Residual Capacity. (FRC) it is the sum of Expiratory Reserve Volume (ERV) and Residual Volume (RV), and measures approximately 3000 ml in a 70kg, average-sized male.

ERV is the maximum volume of air that can be exhaled during normalexpiration. It is about 1000 mL to 1500 mL.