286 Introduction to Anatomy & Physiology Injuries and Disorders of the Nose Your nose is important to your overall health. It acts as a filter to remove dust, irritants, and germs from the air that you breathe. A variety of problems, from the common cold to a deviated septum, can make breathing difficult. The etiology, strategies for prevention, pathology, diagnosis, and common treatments for injuries and disorders of the nose are summarized in Figure 7.19. Rhinitis Rhinitis (righ-NIGH-tis) is an inflammation of the mucous membranes that line the nasal passage. The most frequent cause of rhinitis is the common cold. However, the condition can be caused by anything that irritates these membranes. Possibilities include infections, allergies, strong chemical odors, and certain drugs. Irritation of the nasal membranes causes the release of histamines (HIS-ta-meenz), molecules that trigger a reaction that produces nasal congestion and drainage. Treatment of rhinitis requires removing or minimizing the original irritant and taking medications that contain antihistamines (an-tee-HIS-ta-meenz), which curb the activity of histamines. Septum Problems The septum of the nose is the structure made of cartilage that divides the left and right air passages in the nose. It is normal for the septum not to be Although most animals have a much stronger sense of smell than humans, human olfactory receptors are actually quite sensitive. It takes only a few molecules of an inhaled odor to stimulate the olfactory receptors, which then fire a nerve impulse. Thus, the olfactory receptors can easily become used to an odor to which they are repeatedly exposed. This explains why people who habitually wear a certain perfume or cologne, for example, tend not to smell it on themselves. Why do you suppose different people prefer or dislike different perfumes and other scents? On a biological level, the answer has to do with individual differences in olfactory receptors. A given smell activates different olfactory receptors in different people. When scientists compared olfactory receptors across people, they found that any two individuals are likely to be approximately 30% different. This may seem surprising, but there are about 400 genes, with 900,000 variations, coding the olfactory receptors. Differences in an individual’s sense of smell is therefore not unexpected. How many different basic odors do you suppose there are? Although many smells are derived from a combination of basic odors, scientists have isolated 10 different basic odor qualities from analysis of olfactory perception data. These have been identified as sweet, fragrant, woody/resinous, fruity (non-citrus), chemical, minty/peppermint, popcorn, lemon, decaying, and pungent. Disorders and Infections of the Nose Etiology Prevention Pathology Diagnosis Treatment Rhinitis inflammation of mucous membranes of nasal passage due to infections, allergies, strong chemical odors, or certain recreational drugs avoid exposure to infections and nasal irritants release of histamines causes nasal congestion and drainage physical exam rest, antihistamines Deviated septum injury or genetics none symptoms vary with circumstances physical exam treat symptoms surgical repair when warranted Perforated septum injury, ulcer, long-term exposure to toxic fumes, drug abuse avoid toxic fumes and drug abuse symptoms vary with circumstances physical exam surgical repair when warranted Figure 7.19 Goodheart-Willcox Publisher Copyright Goodheart-Willcox Co., Inc.