Abstract The sections in this article are: Lung Volumes Volume‐Pressure Relations of Respiratory System During Relaxation Total Respiratory System Chest Wall and Lung Effects of Gravity and Posture Changes Throughout Life Span Volume‐Pressure Relations of Respiratory System During Static Muscular Efforts Alveolar Pressure Abdominal and Thoracic Pressures Factors Limiting Volume Extremes Upper Volume Extreme Lower Volume Extreme