Vasomotor rhinitis

In addition to providing us with our sense of smell, the nose conditions and cleans the air we inhale. In its passage through the nose, air is warmed, humidified, and cleaned of foreign particles and microorganisms. Thus, when the air we inhale reaches the throat, it is at body temperature and at 100% humidity. To accomplish this conditioning feat, the lining of the nose produces approximately two quarts of mucus per day, which gives up heat and water to the inhaled air. The mucus also traps foreign matter such as bacteria and viruses and transports them to the throat, where the mucus and everything trapped within it is continuously swallowed. The cells producing the nasal mucus, and the small blood vessels in the lining of the nose which control the amount of mucous membrane congestion, are under the control of the autonomic nervous system, which responds automatically to changes in conditions presented to the nose. A typical example of this is the sneeze, a reflex reaction to a noxious stimulus.