what does mucus do in the respiratory system
Mucus In the human respiratory system, mucus, also known as airway surface liquid (ASL), aids in the protection of the lungs by trapping foreign particles that enter them, in particular, through the nose, during normal breathing.[3] Further distinction exists between the superficial and cell-lining layers of ASL, which are known as mucus layer (ML) and pericilliary liquid layer (PCL), respectively.[4] "Phlegm" is a specialized term for mucus that is restricted to the respiratory tract, whereas the term "nasal mucus" describes secretions of the nasal passages.
Nasal cavity The term "nasal cavity" can refer to each of the two sides of the nose or to the two sides combined. The two nasal cavities condition the air to be received by the other areas of the respiratory tract. Owing to the large surface area provided by the nasal conchae (also known as turbinates), the air passing through the nasal cavity is warmed or cooled to within 1 degree of body temperature. In addition, the air is humidified, and dust and other particulate matter is removed by vibrissae, short, thick hairs, present in the vestibule. The entire mucosa of the nasal fossae is covered by a blanket of mucus, which lies superficial to the microscopic cilia and also filters inspired air. The cilia of the respiratory epithelium move the secreted mucus and particulate matter posteriorly towards the pharynx where it passes into the esophagus and is digested in the stomach. The nasal cavity also houses the sense of smell and contributes greatly to taste sensation through its posterior communication with the mouth via the choanae.