In which part of the lungs is surfactant primarily located?

Surfactant is primarily located in the alveoli, which are the small air sacs in the lungs where gas exchange occurs. The main role of surfactant is to reduce surface tension within the alveoli, preventing their collapse during exhalation and aiding in the expansion of the lungs during inhalation. This is crucial for normal respiratory function, as it ensures that the alveoli remain open and available for efficient gas exchange. The presence of surfactant is vital in maintaining the stability of the alveoli and helps facilitate optimal lung mechanics.

The bronchioles, which are the smaller air passages leading to the alveoli, do not have surfactant. The trachea, as the main airway, also does not contain surfactant, since its function is mainly to conduct air to and from the lungs. The pleural cavity is the space between the lungs and the chest wall, which contains pleural fluid to lubricate the lungs' movement but does not contain surfactant. Therefore, the alveoli are the only part of the lungs where surfactant is primarily produced and utilized.