Structure and Function of the Respiratory System

Before asthma can be discussed in detail, the most important basic facts about the structure and function of the respiratory tract and lungs must be explained. An understanding of the normal healthy functioning of the respiratory organs is a necessary prerequisite to understanding the changes caused by asthma. 

The lung does not serve the sole function of breathing. It would be impossible to speak, whisper, sigh, sob, moan, laugh, or yawn without it. The lungs were once called the mirror of the soul. Both a pleasant sneeze and bothersome hiccoughs depend on healthy breathing. Moreover, the lung indirectly permits us to smell and taste by allowing air to flow through the upper part of the nose.