Human Phys 6.3 Flashcards
Lung mechanics is the study of what?
Mechanical properties of the lung and chest wall, including the diaphragm, abdominal cavity, and abdominal muscles
What is death from lung disease almost always due to?
Respiratory muscle fatigue
How much respiratory work does the diaphragm do?
75%
What is the relationship between alveolus size and collapsing pressure?
As the alveolus size increases the collapsing pressure decreases
What does elastic recoil of the lungs want to do?
Collapse lungs
What does elastic recoil of the chest wall want to do?
Expand lungs
What do the elastic recoil of the lungs and chest wall do?
Balance eachother out at the FRC line
Pneumothorax
Puncture of lung causes atmospheric pressure to rush in and causes collapse of lungs
What does lung compliance reflect?
How easily the lung is distended
Type 1 alveolar cells
Cover most of the alveolar wall
Thin cell thickness and flat (squamous) which allow gas exchange
Type 2 alveolar cells
Plump in size, when stretched secrete surfactant a material that forms a film and reduces surface tension
What does surfactant make easy?
The alveoli to inflate even if they collapse
How does surfactant reduce surface tension?
By decreasing density of water molecules
What does surfactant allow the alveolus to do?
Have low collapsing pressure even at small sizes
What are the primary roles of the surfactant?
Reduce work of breathing by decreasing surface tension forces
Prevent collapse and sticking of alveoli on exhalation
Keeps alveolar size relatively uniform
