Question #e9e17

1 Answer
Nov 15, 2017

Pseudostratified ciliated columnar epithelium is mostly found in the upper respiratory system, where it functions as a way to trap and remove inhaled particles.


Pseudostratified ciliated columnar epithelium is located where there is a need to trap foreign particles in the mucous it secretes and for its cilia to sweep those particles away.

For example. the respiratory system's function is to exchange O₂ and CO₂, so it brings inhaled air into close contact with the blood flowing in capillaries at the alveoli.

But in order to maximize gas diffusion, capillaries and alveoli are made of thin simple squamous epithelium. This delicate tissue has to be protected against large particles such as large dust particles, pollutants, pollen, and pathogens.

So in the upper respiratory tract -- the nose, trachea and bronchi -- some cells of the pseudostratified columnar epithelium secrete mucus to trap particles and prevent them from traveling further down toward the alveoli of the lungs.

In the meantime, the cilia on the tall columnar cells move this mucus -- along with the trapped particles -- away from the lungs so it can be coughed or sneezed out.