Chapter 7 The Sensory Systems 289 Sarah has always practiced good oral hygiene, brushing her teeth and tongue at least twice a day. Two days ago, she had her tongue pierced. Now her tongue is painful and swollen and she feels like she might have a fever. As you read this section, try to determine which of the following conditions Sarah most likely has. A. Tongue infec tion B. Hairy tongue C. Burning mouth syndrome CLINICAL CASE STUDY Infection of the tongue may follow severe biting of the tongue during a traumatic accident, or it may be associated with piercing of the tongue. Antibiotics are used to treat a tongue infection. Fortunately, the human tongue tends to heal quickly. In fact, it heals more quickly than any other part of the body. Spicy foods stimulate not only gustatory cells but also pain receptors in the mouth. Because everyone perceives pain differently, some people enjoy the sensation of spicy foods and others do not. Disorders of the Tongue The powerful muscles of your tongue enable you to speak and to chew and swallow food. As discussed above, taste buds on the surface of your tongue allow you to experience different taste sensations. A variety of disorders, including infections, injuries, and abnormal tissue growth, can affect the appearance and function of the tongue. Some tongue disorders are short-lived and can be remedied with antibiotics. Other disorders require ongoing treatment for an underlying physical condition. The etiology, strategies for prevention, pathology, diagnosis, and common treatments for injuries and disorders of the tongue are summarized in Figure 7.23. Specialized taste cells form in the developing fetus around the 7th to 8th week of gestation. By 13 to 15 weeks, these have evolved into fully formed taste buds. Newborn infants are fully responsive to taste. Since both amniotic fluid and breast milk contain molecules from the mother’s diet, sampling flavors in foods begins in the womb and continues in early infancy. Mothers who consume a variety of healthful foods during pregnancy and lactation therefore give their babies early exposure to these flavors. Nevertheless, infants are born preferring sweet tastes and avoiding bitter tastes (Figure 7.22). The number of taste receptors remains approximately constant from birth through middle age. By about the age of 50, however, the number of taste buds begins to dramatically decline, making food taste blander. Health issues, including nasal and sinus problems, certain medications, dental problems, cigarette smoking, Alzheimer's disease, and Parkinson's disease, can also diminish the sense of taste. Life Span Review 1. Why are developing fetuses able to taste what the mother eats? 2. How well developed is a newborn infant’s sense of taste? 3. Why does the ability to discriminate tastes decline with advanced age? LIFE SPAN DEVELOPMENT: The Tongue and Sense of Taste nd3000/Shutterstock.com Figure 7.22 Mothers who consume a variety of healthful foods during pregnancy and lactation therefore give their babies early exposure to these flavors. Nevertheless, infants are born preferring sweet tastes and avoiding bitter tastes. Copyright Goodheart-Willcox Co., Inc.