The nasal cavity is covered by a mucous membrane, whose upper part consists of an epithelium with: cells producing mucus and ciliate cells covered with very thin hairs, vibratile cilia (see figure opposite). There is an elaborate network of capillary blood vessels extending beneath the epithelium.
Nasal mucus is vital for the proper functioning of the entire respiratory system.
The nose heats and humidifies over 12,000 litres of air-a-day. It works with the help of various defence mechanisms: the epithelium and a dense network of capillary vessels, mucus, vibratile cilia for moving the mucus, cells belonging to the immune system and lots of substances that can block bacteria, viruses and noxious substances.
The nose is also the immune system’s first line of defence.