Basic and Clinical Sciences (BCSE) Practice Exam

What does transpulmonary pressure refer to?

1. Pressure in the alveoli

2. Difference between intrapulmonary and intrapleural pressure

3. Pressure against the chest wall

4. Pressure required for gas exchange

The correct answer is: Difference between intrapulmonary and intrapleural pressure

Transpulmonary pressure is defined as the difference between intrapulmonary pressure (pressure within the alveoli) and intrapleural pressure (pressure within the pleural cavity). This difference is crucial because it influences lung inflation and maintains lung expansion against the forces that tend to collapse the lungs, such as surface tension in the alveoli and elastic recoil of lung tissue. When intrapulmonary pressure is greater than intrapleural pressure, the lungs expand, enabling adequate ventilation. Conversely, a decrease in transpulmonary pressure could lead to conditions like atelectasis, where parts of the lung collapse. This understanding is fundamental in respiratory physiology, as it reflects the mechanics of breathing and the maintenance of respiratory function.