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Hi!
I am battling with this question for quite some time now, but I still haven't found a single source that gives me a complete explanation to the question.
I understand the mechanism behind the the "negativity" of the pleural pressure (meaning I know it stems from the fact that through the elasticity of the lung, it wants to retract, but due to it being connected to the inner thorax through the pleural cavity, that doesn't happen, so it results in subathmospheric pressure);
The thing is, I can't explain to myself why the pleural pressure is lower --> on a schematic picture of the lung, where can I draw the physical pressure vectors which end up yielding a -5 cmH2O pleural pressure? Where does it come from, how exactly is this -5 formed?
From my understanding of physics, if the pleural pressure is always lower than in the alveoli, shouldn't there be a pushing force that constantly expands my lung whether I want it or not? And I know the athmosphere is pushing from outside with the same pressure as the alveoli from the inside (meaning it shouldn't expand), but then we have 2 equal pressures pushing against each other meaning the pleural pressure should be 0?
Sorry if my formulations are a bit confusing, I'm a student from Austria and I am a bit confused myself.
I am battling with this question for quite some time now, but I still haven't found a single source that gives me a complete explanation to the question.
I understand the mechanism behind the the "negativity" of the pleural pressure (meaning I know it stems from the fact that through the elasticity of the lung, it wants to retract, but due to it being connected to the inner thorax through the pleural cavity, that doesn't happen, so it results in subathmospheric pressure);
The thing is, I can't explain to myself why the pleural pressure is lower --> on a schematic picture of the lung, where can I draw the physical pressure vectors which end up yielding a -5 cmH2O pleural pressure? Where does it come from, how exactly is this -5 formed?
From my understanding of physics, if the pleural pressure is always lower than in the alveoli, shouldn't there be a pushing force that constantly expands my lung whether I want it or not? And I know the athmosphere is pushing from outside with the same pressure as the alveoli from the inside (meaning it shouldn't expand), but then we have 2 equal pressures pushing against each other meaning the pleural pressure should be 0?
Sorry if my formulations are a bit confusing, I'm a student from Austria and I am a bit confused myself.
