Function: conduit for air and its conditioning.
- 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 containing numerous lymphocytes, lymphatic tissue in diffuse and nodular forms
Composition: loose connective tissue with abundant blood and lymphatic vessels, diffuse lymphatic tissue and lymphatic nodules, mucus-secreting glands
Function: provide flexibility to the tracheal pipe and maintain patency of the lumen.
Function: binds the trachea to adjacent structures.
Composition: loose connective tissue with large blood and lymphatic vessels, and nerves