alveolarcapillary
The alveolar-capillary, or alveolar-capillary membrane, is the thin barrier through which gas exchange occurs between the air-filled alveoli of the lungs and the blood in the surrounding pulmonary capillaries. It comprises the alveolar epithelium, the capillary endothelium, and the intervening basement membranes, sometimes including a small alveolar interstitial space. This unit forms the primary site where oxygen diffuses into the blood and carbon dioxide diffuses out for exhalation.
Structure and components: The alveolar lining consists largely of type I pneumocytes, which provide most of
Function and physiology: The thin barrier and large surface area enable rapid diffusion of gases driven by
Clinical relevance: Pathologies can thicken or disrupt the alveolar-capillary barrier or reduce surface area, impairing gas