What does negative intrapleural pressure assist with during breathing?

• A. Exhalation of air
• B. Inhalation by expanding lung volume
• C. Decreasing lung capacity
• D. Stabilizing lung tissues

Answer: (B)

Negative intrapleural pressure plays a crucial role in the mechanics of breathing, particularly during inhalation. This negative pressure is created by the elastic recoil of the lungs and the surface tension of the pleural fluid, which helps keep the lungs inflated. When the diaphragm and intercostal muscles contract, the thoracic cavity expands, and the negative intrapleural pressure decreases even further. This pressure differential causes air to flow into the lungs as they expand, increasing lung volume. Consequently, negative intrapleural pressure is essential for facilitating the inhalation of air by allowing the lungs to fill more effectively.

The other choices do not accurately reflect the primary function of negative intrapleural pressure during the breathing cycle. Exhalation involves the relaxation of muscles and the natural recoil of the lungs, which is not directly dependent on maintaining negative pressure. Decreasing lung capacity and stabilizing lung tissues are not primary functions associated with the role of negative intrapleural pressure during the inhalation phase.