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- Mucociliary clearance is an important part of our respiratory defense mechanism. This mucus transport system clears foreign particles and bacteria from the airways. This important mechanism is affected by temperature and humidity.
- Foreign particles (viruses and bacteria) are trapped in an extremely sticky mucus layer lining the airways. Mucus carries the trapped materials into the larynx in a process known as mucociliary clearance. Mucus transport to clear foreign particles is driven by motile cilia.
- Cilia are small, tentacle-like structures with a diameter about 1K times smaller than a human hair, which beat in an asymmetric rhythm. Cilia protrude from most of the epithelial cells lining the airways, densely carpeting the respiratory tract. This was reviewed by scanning electron microscope images.
- Cilia are bathed in a watery fluid. The mucus layer, which traps debris, floats on top of this periciliary fluid. As the cilia beat synchronously, the mucus layer moves, carrying along trapped particles. In a healthy person, cilia beat typically about 15 cycles/second, propelling mucus about 10 mm/minute.