The respiratory epithelium acts to protect and effectively clear the airways and lungs of inhaled infections and irritants, much how the skin protects humans from external pathogens and irritants.

The function and roles of the respiratory system are separated into conducting and respiratory airways. The nose, pharynx, larynx, trachea, bronchi, and bronchioles make up the conducting section, which humidifies, warms, and filters air. Gas exchange takes place in the respiratory system. The respiratory epithelium has three types of cells, each of which plays an important function in regulating how humans breathe. If any of these components of the barrier aren’t working properly, the body becomes vulnerable to infections, viruses, or inflammation, which can disrupt hemostasis.

Respiratory mucosa, which contains epithelium and supporting lamina propria, submucosa, cartilage and/or muscle layer, and adventitia are the four primary histological layers in the respiratory system. The respiratory epithelium is a ciliated pseudostratified columnar epithelium that lines the majority of the respiratory tract except the larynx and pharynx. Though the epithelium is a single layer of cells along the basement membrane, the nuclei are not aligned in the same plane, giving the impression of numerous layers. The mucociliary elevator prevents infection and tissue harm.