The barrier between capillary blood and alveolar air comprising the alveolar EPITHELIUM and capillary ENDOTHELIUM with their adherent BASEMENT MEMBRANE and EPITHELIAL CELL cytoplasm. PULMONARY GAS EXCHANGE occurs across this membrane.

Synonyms: Barriers, Blood-Air, Blood-Air Barriers, Air Blood Barrier, Membranes, Alveolocapillary, Blood Air Barrier, Barrier, Air-Blood, Air-Blood Barrier, Air-Blood Barriers, Barrier, Blood-Air, Alveolocapillary Membrane, Barriers, Air-Blood, Blood-Air Barrier, Alveolocapillary Membranes, Membrane, Alveolocapillary