Static Lung Volumes

Static Lung Volume diagram

Lets begin with normal respiration that is the Tidal volume.

• TV: is the amount of air inhaled or exhaled in one breath during relaxed breathing and its volume is 500ml.
• IRV: inspiratory reserve volume: is the amount of air in excess of tidal volume that can be inhaled with maximum effort. (Its) volume is 3 litres.
• Remember to start labeling after the top of TV
• TV + IRV= IC- Inspiratory capacity: maximum amount of air that can be inspired after a normal tidal expiration. (Its) volume is 3.5 litres

Label the top of the inspiratory loop= maximum possible inspiration

• ERV: the amount of air in excess of tidal expiration that can be exhaled with maximum effort. Volume 1.2 litres. Remember to start labelling after the bottom of TV
• RV: amount of air remaining in the lungs after maximal expiration. Volume is 1.2 litres.
• RV is important as it keeps the alveoli inflated between breaths and mixes with fresh air on next inspiration
• RV + ERV=FRC: amount of air remaining in the lungs after a normal tidal expiration. Volume is 2.4 litres

Label at the bottom of the expiratory loop= maximum voluntary expiration

• Vital capacity VC: amount of air that can be exhaled with maximum effort after maximum inspiration.
• In other words it is IRV + TV +ERV. (Its) vol is 4.7 litres.
• VC is used to assess thoracic muscle strength as well a pulmonary function

Total lung capacity= 5900ml- maximum amount of air the lungs can contain. RV + VC

Note: These values can differ slightly depending on the source you review