This book elucidates the morphological backgrounds of various functional parameters of the human respiratory system, including the respiratory control system, dynamics of the upper and lower airways, gas transport and mixing in the lower airways, gas exchange in the acinus, and gas transfer through the alveolar wall. Presenting the latest findings on the interrelationships between morphology and physiology in the respiratory system, the book’s goal is to provide a foundation for further exploring structure-function relationships in various respiratory systems, and to improve both the quality of basic science, and that of clinical medicine targeting the human respiratory system.