III: Regional Differences in Ventilation Flashcards
Regional differences of ventilation are conditioned by the
Unit
1st phase of Pairways vs Volume
A given P = 1/2 change will result in a small volume change
Como cuando hinchas un globo, que al principio cuesta mas que se infle
Second phase of Pairways vs Volume
P change = 1 –> large volume change
Third phase Pariways vs. Volume
P change = 1/2 –> small changes
At the end of inspiration
Function of fluid between parietal and visceral pleura
Lubricate
Offer support
Where is the negative intrapleural pressure greater
At the apex
Factors conditioning the negative pressure
2 membranes separated by a liquid
Thoracic cage that expands –> pulls parietal pleura –> even more negative P
Gravity –> negative pressure much greater at apex
Where is ventilation more effective
At the base
Why is ventilation more effective at the base
Due to a more positive pressure (gravity)
Apex at alveoli
↑ P = ↑ distentibility = ↓ expansion = ↑ resting volume
Alveoli at base
↓ P = ↓ distensibility = ↑ expansion = ↓ resting volume
What is lost at small airways
Elastic recoil capacity
