What keeps the alveoli from collapsing?

The primary factor that prevents alveoli from collapsing is the transpulmonary pressure. Transpulmonary pressure is the difference between the pressure inside the alveoli and the pleural pressure surrounding the lungs. When this pressure difference is maintained, it contributes to keeping the alveoli inflated.

During inhalation, the negative pressure within the pleural cavity causes the lungs to expand, increasing the transpulmonary pressure, which helps to keep the alveoli open and prevents them from collapsing. This concept is vital in understanding lung mechanics and how the lungs function during different phases of respiration.

Although surfactant production is also essential, as it reduces surface tension within the alveoli and helps to maintain their stability, the question specifically focuses on the mechanism responsible for preventing collapse. In this case, transpulmonary pressure is the most significant factor in this particular context.