Nasal passage

The walls of the nasal passages are coated with respiratory mucous membranes which contain innumerable tiny hair-like cells that act to move waves of mucus toward the throat. Dust, bacteria, and other particles inhaled from the air are trapped by the mucus in the nose, carried back, swallowed and dropped into the gastric juices to nullify any potential harm they might do. The organs of smell are made up of patches of tissue (the olfactory membranes) about the size of a postage stamp and located in a pair of clefts just under the bridge of the nose. Most air breathed in normally flows through the nose but only a small part reaches the olfactory clefts, enough to get a response to an odor. When a person sniffs to detect a smell, air moves faster through the nose, increasing the flow to the olfactory clefts and carrying more odor to these sensory organs.