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Alveolus
Parts and Bonds
Ashley Davidoff MD TheCommonVein.net lungs-0060
Histology of the Large and Medium Sized Airways
Airways are lined by a pseudostratified ciliated columnar epithelium interspersed with mucus secreting goblet cells
Ashley Davidoff
TheCommonVein.net lungs-00674b01-lo res
As the medium sized airways progress to to the small airways they lose many of the goblet cells, become a simple epithelium and remain ciliated
Ashley Davidoff TheCommonVein.net lungs-00675-lo-res

lungs-00677-lo-res.jpg

 At the level of the mebranous airways (respiratory bronchiole, alveolar duct, alveolar sac and alveoli, the mucosa becomes mostly a simple squamous epithelium
Ashley Davidoff
TheCommonVein.net lungs-00677-lo res

 

The Alveolus –
The Buck Ends Here
The alveolus is lined by a simple epithelium ? one cell layer thick. There are two types of lining cells; Type 1 pneumocytes are squamous cells that cover 90% of the surface of the inner lining of the lung , and type II cuboidal pneumocytes that are in fact much more numerous than Type I. They are involved in the production of surfactant . In the lumen there are resident macrophages which play a crucial role in the immune system. The mucosa is grounded by a basement membrane and a lamina propria, and connected to the lamina propria and basement membrane of the surrounding capillary. The alveolus is lined by a thin layer of surfactant. (teal blue)
Ashley Davidoff
TheCommonVein.net
Macrophage
Ashley Davidoff MD
Simple cuboidal cell with reddish foamy and sometimes vacuolated cytoplasm
It produces the phospholipid – part of the surfactant that reduces surface tension and allows the alveoli to remain open
#cells
Ashley Davidoff
TheCommonVein.net
Simple squamous epithelium with pale staining cytoplasm
– flattened for gas exchange, forms a part of the Blood-Gas Barrier
nd sometimes vacuolated cytoplasm
It produces the phospholipid – part of the surfactant that reduces surface tension and allows the alveoli to remain open
#cells
Ashley Davidoff
TheCommonVein.net
The Alveolus 3D
This drawing demonstrates the open mouth view of the alveolus, which is surrounded by its tree like capillary network. The lining single layer of squamous cells (pneumocytes) can be seen peaking through the vessels.
Ashley Davidoff MD. TheCommonVein.net lungs-0022
Result of Cellular Response
The cells of the immune system release cytokines, chemotactic agents and proteases. Immune cells , macrophages and fibroblasts are attracted to the interstitium. Some of proinflammatory agents are toxic to the cell lining causing damage to the surfactant, type 1 pneumocytes and the capillary endothelium. There is progressive edema.
Ashley Davidoff TheCommonVein.net lungs-0692-lo-res

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