In Biology (Class 11, Breathing and Exchange of Gases), Residual Volume (RV) is a crucial respiratory volume that ensures our lungs don't collapse.
Unlike other lung volumes (like Tidal Volume or Vital Capacity), Residual Volume cannot be measured directly using a standard spirometer, because you cannot breathe this air out into the machine.
Residual Volume (RV) is the volume of air that remains in the lungs even after a forceful, maximum exhalation (breathing out as hard as you can).
No matter how hard you blow air out, your lungs will never be completely empty. The air left behind is the residual volume.
In a healthy human adult, the Residual Volume is approximately 1100 mL to 1200 mL (1.1 to 1.2 Litres).
A hard blow to the diaphragm causes a temporary spasm, forcing out some of the expiratory reserve volume and making it feel like you've lost your residual volume, causing a brief, scary inability to breathe.
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