Lesson 5 of 11 · 7 min
Respiratory volumes and capacities
NCERT §14.2.1
A capacity is just two or more volumes added together, and NEET's favourite trap is which volume gets left out.
The lesson in notes
In short
Tidal Volume (TV): the air breathed in or out in one normal breath, about 500 mL. A healthy person therefore moves roughly 6000–8000 mL of air per minute.
Inspiratory Reserve Volume (IRV): the extra air that can be forcibly inhaled after a normal inspiration, on average 2500–3000 mL.
Expiratory Reserve Volume (ERV): the extra air that can be forcibly exhaled after a normal expiration, on average 1000–1100 mL.
Residual Volume (RV): the air the lungs still hold even after a forcible expiration, on average 1100–1200 mL.
Inspiratory Capacity (IC) = TV + IRV: total air that can be inhaled after a normal expiration.
Expiratory Capacity (EC) = TV + ERV: total air that can be exhaled after a normal inspiration.
Functional Residual Capacity (FRC) = ERV + RV: air left in the lungs after a normal expiration.
Vital Capacity (VC) = ERV + TV + IRV: the greatest volume of air that can be breathed in following a forced expiration, or breathed out following a forced inspiration.
Total Lung Capacity (TLC) = VC + RV (equivalently RV + ERV + TV + IRV): all the air the lungs can hold at the end of a forced inspiration.
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Spirogram volumes built into capacities
Dr Matt & Dr Mike · English · Lecture · Open on YouTube