The walls of the nasal cavity, and particularly the flap-like middle and inferior conchae, are coated with respiratory mucous membranes which incorporate a vast number of tiny hair-like cells which act to move waves of mucus toward the throat. Dust, bacteria, and chemical particles which are inhaled from the air are trapped by the mucus, carried back and swallowed; they are then taken care of by gastric juices to nullify any potential harm.
The sense organs themselves are made up of two yellowish-gray patches of tissue, called the olfactory membranes, each about the size of a postage stamp. They are located in a pair of clefts just under the bridge of the nose and at the top of the nasal cavity. The reasons for the coloration are not completely clear, but it seems to be necessary for the membrane to work.
During normal breathing, most of the air flows through the nasal passage, with only a small part reaching the olfactory clefts, but this is enough to get a response to a new smell. When a person "sniffs the air" to detect smells, the air moves through the nasal passage much faster, increasing the flow that makes its way to the olfactory clefts and so carrying more odor to those sensors. If you "follow your nose," you are taking a route that lies straight ahead and is obvious (as the nose on your face), or else you are going ahead without a plan, that is, following wherever instinct leads.
Even though your nasal passage is lined with a highly sensitive mucous membrane, an almost perfect filter for dust, impurities and infectious germs, like any other filter it needs regular cleaning to remove buildup and residue. Many common ailments such as colds (coughs and sneezes, inflammation of the nasal cavities, sinusitis), chronic headaches, earaches (blocked auditory canals) and insomnia have been attributed to clogged nasal passages. NasalCare nasal irrigator is a gentle, natural, yet effective device to help counter these ailments.