Questão 69

Think for a minute about the little bumps on your tongue. You probably saw a diagram of those taste bud arrangements once $\in a$ biology textbook sweet sensors at the tip, salty on either side, sour behind them, bitter $\in$ the back. But the idea that specific tastes are confined to certain areas of the tongue is a myth that "persists $\in$ the collective consciousness, despite decades of research debunking it", according to a review published this month $\in T$ he New England Journal of Medicine. Also wrong: the notion that taste is limited to the mouth. The old diagram, which has been used $\in$ many textbooks over the years, originated $\in a$ study published by David Hanig, a German scientist, $\in 1901$ . But the scientist was not suggesting that various tastes are segregated on the tongue. He was actually measuring the sensitivity of different areas, said Paul Breslin, a researcher at Monell Chemical Senses Center $\in P$ hiladelphia. "What he found was that you could detect things at a lower concentration $\in$ one part relative to another," Dr. Breslin said. The tip of the tongue, for example, is dense with sweet sensors but contains the others as well. The map's mistakes are easy to confirm. If you place a lemon wedge at the tip of your tongue, it will taste sour, and if you put a bit of honey toward the side, it will be sweet. The perception of taste is a remarkably complex process, starting from that first encounter with the tongue. Taste cells have a variety of sensors that signal the brain when they encounter nutrients or toxins. For some tastes, tiny pores $\in$ cell membranes let taste chemicals $\in$ . Such taste receptors aren't limited to the tongue; they are also found $\in$ the gastrointestinal tract, liver, pancreas, fat cells, brain, muscle cells, thyroid and lungs. We don't generally think of these organs as tasting anything, but they use the receptors to pick up the presence of various molecules and metabolize them, said Diego Bohórquez, a self-described gut-brain neuroscientist at Duke University. For example, when the gut notices sugar $\in$ food, it tells the brain to alert other organs to get ready for digestion.