Mechanism of Breathing · NCERT Biology

The intra-pleural pressure is always ________ during normal quiet breathing.

  1. Always positive and above atmospheric
  2. Negative relative to atmospheric pressure
  3. Exactly zero at all times
  4. Higher than intra-pulmonary pressure always
Show answer and explanation

Correct answer: Negative relative to atmospheric pressure

Intra-pleural pressure is the pressure within the pleural cavity. It remains negative (sub-atmospheric), which acts like a vacuum to keep the lungs expanded against the chest wall.

Difficulty: Medium Question 14 of 20

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