Which hair-like structures in the respiratory tract aid in trapping and expelling pathogens?

Cilia are small, hair-like structures that line the respiratory tract and play a critical role in maintaining respiratory health. They are part of the epithelium that covers the airways and function by beating in a coordinated manner. This movement helps to trap and expel pathogens, dust, and other particles that enter the respiratory system, ensuring that these foreign bodies do not reach the lungs.

The effectiveness of cilia in the respiratory system is particularly important because they help to clear mucus, which contains trapped pathogens and debris. This mucociliary escalator mechanism protects the respiratory tract from infections and facilitates the removal of irritants.

The other options listed do not serve this specific function. Microvilli, for example, are involved in absorption and secretion, primarily found in the intestines rather than the respiratory system. Filaments could refer to various structural components within cells, but they do not specifically relate to the trapping and expulsion of pathogens in the respiratory tract. Neurons are nerve cells that transmit signals and play a role in various bodily functions, but they do not have a role in trapping pathogens as cilia do. Thus, cilia are the correct choice for their vital function in respiratory health.