The many cilia present on the surface of the cells of respiratory epithelium, along with the mucus producing goblet cells, are the functional units for the mucociliary escalator. Cilia on the respiratory epithelium beat in a co-ordinated manner. They beat in a caudal direction in the [[Nasal Cavity - Anatomy & Physiology|nasal cavity]] and in a cranial direction in the [[Trachea - Anatomy & Physiology|trachea]] and lower airways. Mucus is swallowed when it reaches the [[Pharynx - Anatomy & Physiology|nasopharynx]]. Constant movement reduces chances that pathogens can adhere to the respiratory epithelium. | The many cilia present on the surface of the cells of respiratory epithelium, along with the mucus producing goblet cells, are the functional units for the mucociliary escalator. Cilia on the respiratory epithelium beat in a co-ordinated manner. They beat in a caudal direction in the [[Nasal Cavity - Anatomy & Physiology|nasal cavity]] and in a cranial direction in the [[Trachea - Anatomy & Physiology|trachea]] and lower airways. Mucus is swallowed when it reaches the [[Pharynx - Anatomy & Physiology|nasopharynx]]. Constant movement reduces chances that pathogens can adhere to the respiratory epithelium. |