What is the main function of alveoli in the lungs?

The main function of alveoli in the lungs is gas exchange. Alveoli are tiny air sacs located at the end of the bronchioles, and they play a critical role in the respiratory system. Their large surface area, combined with a thin wall composed of a single layer of epithelial cells, allows for efficient diffusion of gases. When you inhale, oxygen from the air enters the alveoli and passes through their walls into the bloodstream, where it is then transported to cells throughout the body. Simultaneously, carbon dioxide from the blood moves into the alveoli to be exhaled, helping to maintain the body’s respiratory and metabolic processes.

While other options present relevant aspects of lung function, they do not encapsulate the primary role of alveoli. For example, surfactant production, which is important for reducing surface tension in the alveoli and preventing their collapse, occurs in the alveolar cells but is not the main function of the alveoli themselves. Supporting lung structure relates broadly to components like connective tissues and bronchi, and regulating pH levels is a systemic function influenced by gas exchange, but it is not a specific role of the alveoli.