Why gas exchange surface like the alveoli in your lung are always moist in youtube?

The alveoli in the lungs are always moist to facilitate efficient gas exchange. This moisture helps dissolve oxygen and carbon dioxide, allowing them to diffuse more easily across the thin alveolar membrane. Additionally, the presence of a liquid film reduces surface tension, preventing the alveoli from collapsing and ensuring they can expand fully with each breath. Overall, moisture is crucial for maintaining optimal respiratory function.