This book serves as a unique, comprehensive resource for physicians and scientists training in pulmonary medicine and learning about pulmonary function testing.  Pulmonary function testing and the physiological principles that underlie it are often poorly understood by medical students, residents, fellows and graduate students training in the medical sciences.  One reason is that students tend to get overwhelmed by the basic mathematical descriptions that explain the working of the respiratory system and the principles of pulmonary function testing.  Another reason is that too many approaches focus on the math without explaining the clinical relevance of these principles and the laboratory testing that enables us to measure the very lung function that these principles are describing.  This book answers that need by providing a series of chapters that guide the reader in a natural order of learning about the respiratory system.