Location: connects the nasal cavities to the larynx named nasopharynx and oral cavity to the esophagus named oropharynx
Location: auditory (Eustachian) tubes connect the pharynx and the middle ears
- Ciliated cells - the most numerous of the cell types, extend through the full thickness of the epithelium.
Function: provide a coordinated sweeping motion of the mucus coat -"ciliary escalator" - that serves as an important protective mechanism for removing small inhaled particles.
- Mucus (goblet) cells - are interspersed among the ciliated cells and also extend through the full thickness of the epithelium.
Function: unicellular mucin-secreting glands.
- Brush cells -columnar cells that bear microvilli. The basal surface is in synaptic contact with the afferent nerve endings that penetrate the basal lamina and form trigeminal nerve.
Function: receptor cells of general sensation.
- Small granule cells - their cytoplasm processes is sometimes observed extending to the lumen and cytoplasm contains numerous, membrane-bonded, dense-core granules.
Function: release polypeptide hormones and/or catecholamines that are thought to function in reflexes regulating the airway or vascular caliber.
- Basal cells
Function: serve as a reserve population by maintaining individual cell replacement in the epithelium.
Function: conditioning (warming, moistening and removal of particulate materials) of the air, prevention the epithelium from dehydration by moving air.
Composition: loose connective tissue with numerous elastic fibers
Function: guard for infective agents.