PART II: BIOLOGICAL CONSIDERATIONS
Understanding inhalation aerosol therapy requires a knowledge of lung function, particularly as it relates to the mechanical properties of the lung during the process of ventilation. This chapter is intended to supply basic information on lower airway physiology and pharmacology. The upper airways, consisting of the nasopharynx region, have not been included, even though the mouth and pharynx are critical regions to consider in inhalation aerosol therapy because of the potential for significant impaction and loss of aerosolized substances. Although emphasis has been placed on lung function under normal conditions, alterations in lung function caused by pathophysiologic states have been incorporated into the text where appropriate.