@@Lung structure

 

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

• No gas exchange
• i.e. anatomical dead space
• About 150mLs

Z17 to Z23 - Transitional and respiratory zone

• About 2.5L to 3Ls

 

Alveolar are polyhedral, not spherical, and not all surface areas are available for gas exchnge.

--> Total surface area can only be estimated.

 

Diaphragm

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

Respiratory muscles

[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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