Static Lung Volumes

aka BSCC Physiology 006

Basic Science in Clinical Context Examination: 2 minutes long in 2 parts.

  • Exam candidate answering a question (under exam conditions)
  • Professor providing a more detailed explanation (with transcript)
Please draw a diagram to describe static lung volumes
Examinee response: Drawing and explanation in real-time video/audio
Examiner Explanation
Transcript

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

BSCC Basic Science in Clinical Context 700 2

Basic Science

in Clinical Context

Emergency physician MA (Oxon) MBChB (Edin) FACEM FFSEM with a passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books |

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