At the end of a spontaneous 500 mL inspiration, the PA is 0 mm Hg, and at the end of a positive pressure lung inflation to 500 mL, PA is 10 mm Hg.Why does the lung contain the same volume at these two different alveolar pressures?

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Quizplus · Accepted Answer

Figure 3-4 compares PPV and SB. The lung diagrams illustrate conditions at the end of an inspiration. Although the trAnswerpulmonary pressures were achieved by different meAnswer in SB and PPV, PL is 10 cm H₂O in both instances. This meAnswer that elastic lung fibers are stretched to the same extent in both instances. The PPV inspiration places no more stress on the lung than the SB inspiration, although PA is 10 cm H₂O greater in PPV than in SB. This fact has relevance to therapeutic lung expAnswerion techniques used in respiratory care. Given normal inspiratory muscle function, a mechanical positive pressure inspiration is not in some way superior to a spontaneous inspiration in expanding the lung, nor is a 500 mL positive pressure breath any more likely than a 500 mL spontaneous breath to injure the lungs.

At the End of a Spontaneous 500 ML Inspiration, the PA