Mechanism of Breathing · NCERT Biology

Which of the following describes the correct sequence of events for inspiration?

  1. Increased thoracic volume -> Decreased pulmonary pressure -> Air flows out
  2. Decreased thoracic volume -> Increased pulmonary pressure -> Air flows in
  3. Increased thoracic volume -> Decreased pulmonary pressure -> Air flows in
  4. Decreased thoracic volume -> Decreased pulmonary pressure -> Air flows in
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Correct answer: Increased thoracic volume -> Decreased pulmonary pressure -> Air flows in

Inspiration starts with an increase in thoracic volume, which leads to a corresponding increase in pulmonary volume. This causes pulmonary pressure to drop below atmospheric pressure, forcing air into the lungs.

Difficulty: Medium Question 16 of 20

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