Respiratory epithelium is a type of epithelium found lining the respiratory tract, where it serves to moisten and protect the airways.It also functions as a barrier to potential pathogens and foreign particles, preventing infection and tissue injury by action of the mucociliary escalator.ertain parts of the respiratory tract, such as the oropharynx, are also subject to the abrasive swallowing of food. To prevent the destruction of the respiratory epithelium in these areas, it changes to stratified squamous epithelium, which is better suited to the constant sloughing and abrasion.