Which pressure changes with the phases of respiration but is always negative?

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Quizplus · Accepted Answer

Intrapleural pressure is the pressure within the pleural cavity, and it is always negative under normal conditions. This negative pressure is essential for keeping the lungs expanded. During the phases of respiration (inhalation and exhalation), intrapleural pressure changes but remains negative to maintain lung expansion against the elastic recoil of the lungs.

Which Pressure Changes with the Phases of Respiration but Is