IV: Lung Dynamics Flashcards
Rib cage TENDS to
Expand
Lungs ALWAYS
Retract
What is the cause of pneumothorax
Removal of the negative pressure from pleura –> too much retraction
When will the rib cage start contracting
At maximum inspiration, it will stop expanding and will start contracting
In minimal insuflation
Retraction (alveolus) > expansion (thoracic cage)
In resting respiratory volume
Retraction (alveolus) = expansion (thoracic cage), F=0
In deep breathing
Retraction alveolus (alveolus)»_space; Expansion (thoracic cage)
When is there more retraction of alveolus
Deep breathing
At what % will the rib cage start retracting and stop expanding to avoid bursting
At 60%
When does functional residual capacity occur
At the end of normal expiration, when barometric and alveolar pressures both = 0
Behavior of pressure at high volumes
Positive pressure
Behavior of pressure at low volumes
Pressure negative, drops below atmospheric pressure
What must be true between the 2 ends of airway for air to flow
There must be a pressure difference between the two ends
Laminar type of flow
Slow flow in the same direction
Where is velocity the greatest at a laminar flow
At the middle
Transition type of flow
Very fast flow with variable direction of flow
What section of airway is characterized by transitional flow
Branching airways
Turbulent type of flow
Fastest flow because flow does not follow a linear direction
Poiseuillle’s equation application to turbulent flow explanation of why is it present at upper airways
High radius increases Q, which means that there will faster flow at those areas
Upper airways
Order of flow from slowest to fastest
Laminar < transitional < turbulent
Flow will directly depend on
Reynolds number
Reynolds number will be directly proportional to the
Radius
What Reynold number will determine a turbulent flow
R > 2000
How is resistance impacted by a decrease in radius
Decrease in radius will increase resistance
R = 8nL/∏r4
