*6.2.1 Role of cilia in mucociliary clearance*

It has been estimated that cilia beat about 12 to 15 HZ in waves that are well coordinated. This ciliary motion has been observed to be metachronal i.e. backto-front and is directed towards the pharynx [43]. With this motion, particulate matter trapped in mucus including bacteria and viral particles is moved towards the pharynx by being propelled through the vocal cords and glottis. As a result of this constant ciliary movement, an estimated 30 ml of respiratory mucus is discharged into the oral or nasal cavity or swallowed [43].
