Function: terminal air spaces were gas exchange takes place.
Composition: thin-walled polyhedral chambers that are surrounded and separated from one another by a thin connective tissue layer with numerous blood capillaries. Each alveolus is confluent with a respiratory bronchiole, by means of:
Function: release of lamellar bodies into the alveolar space. They are rich in phospholipids among which is the surface active agent surfactant. It forms a monomolecular layer over the alveolar epithelium
Function: receptors that monitor air quality in the lung
Location: the tissue between adjacent alveolar air spaces. The openings in the septa - alveolar pores of Kohn, allow circulation of air from one alveolus to another
Function: site of air-blood barrier
Location: in connective tissue of the septum and in the air space of the alveoli
Function: remove inhaled particulate matter from the air spaces and red blood cells from the septum