This reference presents basic concepts of respiratory function in normal and diseased states. The volume stresses a quantitative approach to physical parameters used as indicators of normal and diseased respiratory functions. The contents of this reference encourages medical students, residents and fellows to become “clinical detectives”, by presenting information aimed at enhancing their understanding of how normal respiratory mechanisms are altered by diseases that affect pulmonary ventilation and/or blood perfusion, tissue oxygenation, acid-base balance, respiratory mechanics, oxygen and carbon dioxide transport, control of breathing, and so on.