Intrapleural pressure is the pressure of the air within the pleural cavity, between the visceral and parietal pleurae. This pressure changes during different phases of breathing.
<em><u>Due to certain characteristics of the lungs, the intrapleural pressure is always lower than, or negative to, the intra-alveolar pressure. It remains approximately –4 mm Hg throughout the breathing cycle.</u></em>
<em><u>Therefore; if the intrapulmonary pressure was 760 mm hg then the intrapleural pressure will be (760 -4) mm Hg, that is 756 mm Hg</u></em>
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