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. Author manuscript; available in PMC: 2022 Nov 23.
Published in final edited form as: Pediatr Clin North Am. 2017 Oct;64(5):1017–1037. doi: 10.1016/j.pcl.2017.06.004

Figure 1.

Figure 1.

Schematic of a healthy alveolus. The alveolar epithelium and capillary endothelium are intact. The characteristics of the pulmonary circulation and intact epithelial endothelial barrier allow for formation of the alveolar wall liquid (AWL) while maintaining the air-filled, fluid-free, status of the alveoli. The AWL facilitates gas exchange and is a medium for dispersal of surfactant and alveolar macrophages, which is essential for maintaining alveolar stability and host defenses. The intact sodium-dependent vectorial transport across type II alveolar epithelial cells regulates the removal of excess alveolar fluid.

From Sapru A, Flori H, et al. Pathobiology of acute respiratory distress syndrome.

Pediatr Crit Care Med. 2015 Jun;16(5 Suppl 1):S6–22. doi: 10.1097/PCC.0000000000000431.