What is the volume of air present in the lungs when the lungs are at rest (in between breaths)?

Spirometry—Total Lung Capacity and Subdivisions

The gas volume in the lung after a maximum inspiration is called thetotal lung capacity [TLC; usually 6 to 8 L]. TLC can be increased in COPD either by overexpansion of alveoli or by destruction of the alveolar wall, resulting in loss of elastic tissue, as in emphysema [seeFig. 13.4].78 In extreme cases, TLC can be increased to 10 to 12 L. In restrictive lung disease, TLC is reduced, reflecting the degree of fibrosis, and can be as low as 3 to 4 L [seeFig. 13.4].78

Following maximum expiratory effort, some air is left in the lung and constitutes the RV [approximately 2 L]. However, usually no region develops collapse because distal airways [