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(单词翻译:双击或拖选)
Pre-Listening Vocabulary
receptor: a cell or nerve that responds to a sense
roof of one’s mouth: the palate; above the top of the tongue
contract: get smaller
sensation: feeling
temples: two flat upper parts at the side of the forehead
Your Brain Feels No Pain
You can whine about an earache5 or a headache, but you can’t complain about pain in the brain. The human brain has no pain receptors. It can’t tell itself that it hurts. If the brain feels no pain, what is brain freeze? Brain freeze, also called an ice cream headache, occurs when you eat or drink something cold too quickly. When ice cream touches the roof of your mouth, the blood vessels6 in your mouth contract. This sends a message to the brain about a change in your body heat. The brain overreacts and tries to conserve heat by contracting the blood vessels in your head. When the threat is over, the blood vessels in the head relax and dilate. This sends a quick rush of blood to the head. You feel this rush of blood as pain in your temples, face, or neck, but not in your brain. Try pressing your tongue against the roof of your mouth to relieve the sensation of brain freeze.
点击收听单词发音
1 whine | |
v.哀号,号哭;n.哀鸣 | |
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2 minor | |
adj.较小(少)的,较次要的;n.辅修学科;vi.辅修 | |
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3 dilate | |
vt.使膨胀,使扩大 | |
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4 conserve | |
vt.保存,保护,节约,节省,守恒,不灭 | |
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5 earache | |
n.耳朵痛 | |
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6 vessels | |
n.血管( vessel的名词复数 );船;容器;(具有特殊品质或接受特殊品质的)人 | |
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