Video narration
When you take a normal breath, what's one amount of air-and what's a capacity? TV is air moved in or out in a normal breath: about 500 milliliters. IRV is extra air inhaled, about 3,000; ERV, extra air exhaled, about 1,100. RV, about 1,200, remains after maximal exhalation and cannot be voluntarily exhaled. Here's the key: capacities aren't four more separate volumes. Each combines the same four amounts differently. IC = TV + IRV, about 3,500 milliliters: a normal breath plus extra inhalation. FRC = ERV + RV, about 2,300: air remaining after a normal exhale. VC = IRV + TV + ERV, about 4,600: the most you can exhale after your deepest inhale. TLC = IRV + TV + ERV + RV, about 5,800: all four amounts. These adult values are approximate; yours vary. Back to your breath: a volume is one measured amount; a capacity combines amounts to describe a larger part of breathing.