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Airway Structure: Epithclium

RESPIRATORY PHYSIOLOGY

Mucus-

Goblet (mucous) celi Basement membrano

1 Gliated \ B 1 cells \ c Nerve Basal celi

Goblet celi (discharging)

Nerve

Serous

celi

Kulchitsky

celi

Trachea and large bronchi. Ciliated and goblet cells predommant, wlth some serous cells and occasional brush cells and Clara cells. Numerous basal cells and occasional Kulchitsky cells are present

membranę celi

Magnified detail of cilium

Bronchiolcs. C-ilialed cells dominant and Clara cells progressively increase distally along airways. Goblet cells and serous cells decrease distally and are absenl in terminal bronchioles

UlTRASTRUCTURE OF TRACHEAl, BRONCHIAL, AND BRONCHIOLAR EPITHEUUM

Figurę 5.4

^The respiratory airways are lined by a pseudostratified, ciliated ilumnar epithclium. In smaller airways the epithclium may bccome !.»w columnar or simple cuboidal. Tłie ciliated cells conslitute approximately 30% ot the total celi population. Goblet cells (30% of celi population) secrete mucus that coats the epithelial cells. This mucous coating protects the epithelial cells from desiccation and traps inhaled particulates that are then transported up the airways and out ot the lungs by the ciliated cells—a proceSS tefrned mucocil* tary transport. Basal cells (30% of celi population) are stem cells that give rise to the goblet, ciliated, and brush cells. nie func.tion of brush (ells ( 3% of celi jFopulałion) is not resolved. niev may reprrsrnt goł>-let cells that have released thcir contents. or they may have a sensory role. nie Kulchitsky cells (3% ul celi population) sccrctc a num-ber of paracrine factors that likely regulate the function of nearby cells. They are part ot the bodies diftuse neuroendocrine system (DNES). Clara cells secrete a surfac tant-fike materiał that reduces sur-face tension of the bronchioles. They may also degrade inhaled tox-ins. The func.tion of the secretory product of the serous cells is not known.

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