Which structure helps to filter and warm the air before it reaches the lungs?

The nasal cavity plays a crucial role in filtering and warming the air before it travels to the lungs. It is lined with mucous membranes and tiny hair-like structures known as cilia, which work together to trap dust, pollutants, and pathogens, preventing them from entering the respiratory system. Additionally, as air passes through the nasal cavity, it comes into contact with this moist surface, which warms and humidifies it, making the air more suitable for the delicate tissues of the lungs. This process is essential for maintaining optimal respiratory function and protecting the lower respiratory tract from irritants.

In contrast, the trachea and bronchi primarily serve as conduits for air passage rather than as filters or heaters, focusing on delivering air to the lungs. The alveoli are tiny air sacs where gas exchange occurs, but they do not play a role in the initial filtration or warming of air.