Final answer:
Surfactant reduces surface tension in the alveoli, enhancing lung compliance and preventing alveolar collapse, which in turn leads to improved gas flow and exchange efficiency.
Step-by-step explanation:
The sequential additions of surfactant change this lung system primarily by reducing surface tension, which in turn enhances lung compliance. Surfactant acts like a detergent, allowing the alveoli to inflate more easily by reducing the work needed to expand them, thereby preventing alveolar collapse. This is especially critical for maintaining stable alveoli throughout the breathing cycle, as surfactant ensures that surface tension decreases as alveoli become smaller, preventing the collapse of small alveoli and overexpansion of large alveoli.
Lung compliance is directly related to how easily the lungs can stretch. A higher lung compliance implies a greater ability of the lungs to stretch, leading to a larger lung volume and thus lower air pressure within the lungs. By reducing surface tension, surfactant allows the lungs to expand more readily, thus contributing to improved gas flow.