300 million alveoli, 1/3mm in diameter => 50-100 m2 surface area
Z0 - Trachea
Z1 - Bronchi
Z4 - Bronchioles
Z16 - Terminal bronchioles
Z17-19 - Respiratory bronchioles
Z20-22 - Alveolar ducts
Z23 - Alveolar sac
Z0 to Z16 - Conducting airway
Z17 to Z23 - Transitional and respiratory zone
Alveolar are polyhedral, not spherical, and not all surface areas are available for gas exchnge.
--> Total surface area can only be estimated.
The diaphragm descends about 1cm during tidal inspiration.
During a vital capacity breath, total movement is about 10cm.
Diaphragmatic contraction is responsible for 70% of the tidal volume
[Need to add]
NB: During tidal breathing, peak alveolar pressure is +1cmH2O. Mouth pressure is atmospheric.
?need to add respiratory muscles
=== to be added ===
upper
lower
alveoli
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