What type of epithelium is the "respiratory epithelium"? (Hint: this is NOT the same thing as the "respiratory membrane". The respiratory epithelium is the epithelium that is found in respiratory mucosa.)

The respiratory epithelium is a type of ciliated pseudostratified columnar epithelium.

Explanation:

The epithelium (a type of tissue) lines the blood vessels and inner-outer surfaces of organs. Their function includes protection, secretion, absorption, transport, etc. Based on the shape, they are classified as squamous, columnar, and cuboidal. Also, they can be simple epithelium (a single layer of cells) or stratified (layers of two or more cells).

Respiratory epithelium (airway epithelium) is a type of ciliated pseudostratified columnar epithelium. It is the epithelium that is found in the respiratory mucosa and lines most of the respiratory tract. It protects and moist the airways. It prevents infection by the self-cleaning mechanism of the airways (mucociliary clearance) and thus acts as a barrier to pathogens and foreign particles. It also secretes mucus and prevents tissue injury. The respiratory epithelium contains four types of cells-ciliated, goblet, club and airway basal cells. The arrangement of these multiple cell types as a single layer results in the non - alignment of their nuclei in the same plane. So the epithelium appears as layered or stratified. Hence the name pseudostratified or falsely layered.