Hair-like structures that filter inspired air are found in which part of the respiratory system?

The hair-like structures that filter inspired air are known as cilia, which are located in the respiratory system, particularly in the nasal cavity and other upper respiratory passages. These cilia play a crucial role in trapping dust, pollen, and other particulate matter from the air we breathe, thus preventing these particles from entering the lower respiratory tract.

In the nasal cavity, the cilia work in conjunction with mucus-producing cells to create a mucociliary escalator system, which helps to keep the airways clear of debris and pathogens. This mechanism is vital for maintaining healthy respiratory function and protecting the lungs from irritants.

While other parts of the respiratory system, such as the bronchi and trachea, also contain cilia and are part of this mucociliary mechanism, the nasal cavity is the primary site where cilia first encounter and filter the air before it moves deeper into the respiratory system. Alveoli, on the other hand, are the sites of gas exchange and do not have cilia, as their primary function is to facilitate the transfer of oxygen and carbon dioxide rather than filtration of inspired air.