英語聽力文摘740 年齡與嗅覺和味覺的關(guān)系

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One of the more puzzling consequences of old age is a decreasing ability to appreciate the taste of a fine meal. Actually, the problem is not only a matter of taste. It also has to do with smell.

Combined Senses

When we eat something, we rely on a combined sense of taste and smell to experience flavor. The next time you’re eating fruit-flavored candy, try this. Grab a handful of candy, close your eyes, and pick one. While pinching your nose shut, pop the candy into your mouth.

Chances are you’ll taste the tart sweetness of the candy, but you won’t recognize a particular flavor. Now let go of your nose. Presto! The savory flavor of banana-grape fills your mouth.

Taste is a limited sense; the taste nerves in the mouth and tongue only detect combinations of sweet, sour, salty and bitter. Flavors, on the other hand, vary widely, numbering in the tens of thousands. When we experience these many flavors, we use our nose as much as our mouth.

Smell And Flavor

For example, when you chew a piece of candy, you inhale the candy’s chemicals through your mouth and exhale them through your nose. As they pass through the nose, the chemicals trigger receptors that send smell and flavor signals to the brain.

The body tends to break down in old age, and taste and flavor receptors are no exception. Although taste buds in the mouth tend to lose some sensitivity, it is the decrease in the number of active flavor receptors in the nose that make it more difficult for elderly diners to truly savor an exquisite meal.