Please help. . . . Cells lining the trachea have whip-like motile extensions on their free surfaces. What are these extensions, what is their source, and what is their function?
These whip-like motile extensions on the free surfaces lining the trachea is called cilia. These are tiny hairs in the respiratory tract and their function is to beat mucus and dirt continuously so these will move up and out of the lungs.
