Lectures 4 + 5: Lung Mechanics Flashcards
Intrapleural pressure is always ______ during normal breathing.
Intrapulmonary pressure (which is the pressure in the alveoli: Palv) ranges from negative to positive during respiration.
Transpulmonary pressure = _______ - _______. This creates the suction to keep the lungs inflated and is known as alveolar ______ pressure.
Negative
Transpulmonary pressure = Intrapulmonary pressure - Intrapleural pressure
Alveolar Distending Pressure
FRC is the ____ _____ ______, and it represents the amount of air in the lungs at the end of normal respiration (so ERV + RV).
Functional Residual Volume
_____ is the term that describes the difference between the Inspiration and Expiration pathways on the Pressure Volume curve. What is this difference due to?
Hysteresis
It is due to Surfactant.
What happens to the way surfactant lowers surface tension as alveolar radius changes?
As alveolar radius decreases, Surfactant lowers the surface tension even more.
How does the cause of ARDS differ from that of NRDS?
In ARDS, patients produce dysfunctional surfactant, while in NRDS the newborn is born premature and does not produce enough surfactant.
Is Artificial surfactant a viable treatment for ARDS or NRDS?
NRDS, but not ARDS
Keep in mind that Gravity exerts effects on Pleural pressure. Where is Pleural pressure greatest in the lung, and where is it lowest? What effect does this have on how much the alveoli in these areas are inflated?
Pleural pressure is greatest (least negative) at the BASE of the lung and lowest (most negative) at the APEX of the lung. This means the alveoli are most inflated at the APEX.
When Reynold’s number is high, flow is _____.
Turbulent
So, small diameter vessels have LAMINAR flow.
While resistance is high in the smaller airways, they are arranged in parallel, so total Resistance is low because the individual Resistance components are added as ______.
Reciprocals.
