Pneumocyte

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The alveoli are lined with two types of cell, the Type I and Type II pneumocytes.

1 Type I
2 Type II
3 See also
4 External links

[edit] Type I

The Type I pneumocyte is a very large, thin cell stretched over a very large area. This cell cannot replicate and is susceptible to a large number of toxic insults. Type I pneumocytes are responsible for gas exchange occurring in the alveoli.

[edit] Type II

Alveolar type II cell, the lamellar bodies can be seen leaving the surface of the cell.

The Type II granular pneumocyte is a roughly cuboidal cell that is usually found at the alveolar septal junctions. There are 10% type II cells and 90% type I pneumocytes within the alveoli. Type II cells only constitute 1 to 5% of the alveolar surface area as they are cuboidal rather than squamous in shape. This cell is responsible for the production and secretion of surfactant.

The Type II pneumocyte can replicate in the alveoli and will replicate to replace damaged Type I pneumocytes.