Pseudostratified ciliated columnar epithelium cells function as a protective layer in the respiratory system of humans, according to CliffsNotes. These specialized cells feature rectangular shapes, vertical appearances and hair-like cilia on the end, while the nucleus is near the base.
Each elongated cell has 200 to 300 cilia protruding off the end. A group of pseudostratified ciliated columnar epithelium cells connects to each other thanks to tightly packed junctions creating a semipermeable membrane, according to Davidson College's Biology Department. This membrane allows some microscopic elements to pass through each cell while keeping other items out.
In the lungs, the rowing action of cilia remove particulate matter from the inner lining in order to prevent infections. Goblet cells, which are responsible for a mucous lining in the lungs, are interspersed among the epithelium. Davidson College reveals both of the cells work in tandem to prevent mucous buildup and keep particulates from accumulating.
CliffsNotes states that the "pseudostratified" characterization comes from the fact that ciliated columnar epithelium cells appear to have multiple layers when there is actually just one cell. This appearance is caused by nuclei which are out of alignment and towards the bottom of the cell as opposed to the middle. The columnar nature allows the epithelium cells to be flexible as air is exhaled and inhaled at different rates.