Respiratory epithelium composition

Inhaled air travels along the conductive airways until it reaches the very distal respiratory part formed by the respiratory airways, which are terminated by the sack like compartments of the alveoli. The surface of these air-filled compartments is formed by epithelial cell layers, the alveoli by the alveolar epithelium, respiratory airways by the respiratory epithelium, and conducting airways by the bronchial epithelium (Fig. 1). According to its localization along the airways the epithelial cell layers differs with regard to its cellular composition, epithelial barrier, and transport function. 

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