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上期划线句答案
Mr Waggett argues that slimming drugs can cause users to lose muscle as well as fat; shedding weight also inspires people to tone up, he believes: “It gives them a catalyst for change.”
瓦格特先生认为，减肥药会导致使用者在减掉脂肪的同时失去肌肉；他认为，减肥也能激励人们变得更强壮：“这是一种改变的催化剂。”
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本期内容
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双语阅读
Para.1
We get thirsty when we exercise heavily, because as we sweat, our blood volume decreases. Most areas of the brain are separated by the blood-brain barrier, a layer of cells that prevents harmful toxins and pathogens from infecting the brain. But certain parts of the brain fall outside this barrier, allowing for rapid detection of changes in our blood. When we lose blood volume from exercising or eating salty foods, neurons in these parts of the brain send a signal to trigger the feeling of thirst.
Para.2
Three parts of the brain process thirst: the subfornical organ (SFO), the organum vasculosum lamina terminalis (OVLT) and the median preoptic nucleus (MnPO). Both the SFO and OVLT are located outside the blood-brain barrier. In a 2018 study in mice, Oka uncovered that while all three areas have neurons that drive drinking when those nerve cells are excited, the MnPO is in the middle of this process. It transmits thirst signals from the SFO and OVLT to other parts of the brain to prompt drinking.
Para.3
It takes about 30 minutes after you swallow water for it to be absorbed and circulate in your body, Oka said. But your body begins to send signals to your brain that you are receiving water well before you are fully rehydrated. With just the initial sip, your brain releases a rush of the neurotransmitter dopamine. Most scientists agree that dopamine is involved in reward-seeking, movement and motivation. Critically, dopamine prompts animals to exert energy on acts that give us a reward or help keep us alive, including eating and drinking.
Para.4
Exactly how drinking water triggers the release of dopamine is still unknown. But in a 2019 study published in the journal Neuron, Oka and his colleagues discovered that thirsty mice that drank water released dopamine, whereas thirsty mice that received water directly to their gut did not. This suggests the act of drinking — and not thirst satiation — releases the neurotransmitter. Oka said this explains why dehydrated patients who are administered IV fluids don't experience the same reward they do from drinking a cold glass of water.
Para.5
Yet gulping isn't the only mechanism that helps to halt thirstiness. After water travels down to the gut, the body detects a drop in the blood's salt-to-water ratio. This leads to a rise in the levels of a hormone called vasoactive intestinal peptide (VIP). This hormone, rather than the water itself, helps to activate neurons that signal to the brain that the body is satisfied. Much about how this process works is a mystery; researchers still don't know where VIP comes from or how its release is triggered.
本文节选自：LiveScience（生活科学）
发布时间：2024.10.7
作者：NEWS
原文标题：Why does drinking water feel so good when you're thirsty?
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写作句总结
原句：Much about how this process works is a mystery.
结构：Much about [topic] is a mystery.
例句：Much about the effects of social media on mental health is a mystery.
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阅读理解题
Which of the following best describes the main idea of the article?
A) The importance of hydration for physical performance
B) The effects of salt intake on thirst levels
C) The role of dopamine in reward-seeking behavior
D) The complex mechanisms of thirst regulation in the brain
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校对 | 慢慢
词汇词组 | 胖葛柔儿
划线句讲解 | 流木
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