What is the importance of the airways

The lining of the respiratory tract

We breathe in and out about 20,000 times a day. With every breath, numerous tiny dust particles and droplets, irritating pollutants and microscopic pathogens (bacteria, fungi or viruses) can get into the airways. For this reason, the entire respiratory tract (except for the throat, epiglottis and vocal cords) is lined with a highly specialized mucous membrane that is supposed to protect our respiratory organs from harmful substances.

The mucous membrane in the airways consists of what is known as the ciliated epithelium. It is a real carpet of millions of cells with flexible hairs, the cilia. In between there are individual, mucus-forming goblet cells. These produce a watery, transparent mucus that lies over the cellular carpet and thus wets the entire surface of the mucous membrane and keeps it constantly moist. In this protective film, the cilia move like waves in the direction of the throat, beating continuously about 1000 times per minute. In the windpipe speeds of up to 1 cm per minute are achieved. Small particles (such as dust particles and bacteria) stick to the moist mucous membrane and are then transported upwards towards the throat by the rhythmically beating cilia, like on a conveyor belt. Once in the throat, the foreign substances bound in the mucus are then usually involuntarily swallowed down into the stomach. Only when the function of the cilia is disturbed or destroyed (e.g. due to cigarette smoking or a flu-like infection) does a more frequent cough occur, which takes over the bronchial cleaning as a replacement motor.