What are the four main lung volumes, and what does each represent in terms of air movement during breathing?
The four main lung volumes are tidal volume (TV), the amount of air moved during quiet breathing (~500 mL); inspiratory reserve volume (IRV), the extra air that can be inhaled after a normal breath (1900–3100 mL); expiratory reserve volume (ERV), the extra air that can be exhaled after a normal breath (700–1200 mL); and residual volume (RV), the air remaining in the lungs after maximum exhalation (1100–1200 mL).