Alveolväggar

Alveolväggar, also known as alveolar walls, are the fundamental structures of the alveoli, the tiny air sacs found in the lungs of mammals and birds. These walls are remarkably thin, typically only one or two cells thick, which is crucial for efficient gas exchange. The primary cell type forming the alveolar wall is the type I pneumocyte, a squamous epithelial cell that provides a large surface area for diffusion. Scattered among the type I pneumocytes are type II pneumocytes, which are cuboidal cells responsible for producing surfactant. Surfactant is a fluid that reduces surface tension within the alveoli, preventing them from collapsing during exhalation and making breathing easier.

The alveolar wall is also a complex barrier containing a basement membrane, which fuses with the basement membrane of the adjacent capillary endothelium. This fused basement membrane forms the respiratory membrane, where oxygen from inhaled air diffuses into the bloodstream and carbon dioxide from the blood diffuses into the alveoli to be exhaled. The walls are further supported by a network of elastic fibers, which allow the alveoli to expand and recoil during breathing. Small pores, known as Pores of Kohn, can connect adjacent alveoli, allowing for collateral ventilation. This intricate structure of the alveolväggar is essential for the vital process of respiration.