ABSTRACT
The airways represent a unique organ system in the body. Their structure allowing
air to come into close contact with blood is one of the principal adaptations
permitting the existence of terrestrial life. This adaptation also makes the airways
useful as a route of administration of drugs in the inhaled, or aerosol, form. This
chapter provides an overview of the physiology of the airways, excluding the
nasopharyngeal regions of the airways. Aspects considered relevant to the
practical and theoretical application of inhaled substances are emphasized.
