英語聽力文摘 致命的脫水
脫水
If I were to stop drinking water right now, how long could I live?
There are different factors involved here. A human being isn’t an automobile which needs a certain amount of gas. There are conditions under which a person could die of dehydration within a single day, and other conditions whereby a person might live for over a week. It’s unlikely, though, anyone could go much beyond that.
Water comes into our systems not just from drinking but from eating as well. It goes out of us through urine, through sweat, and even through exhaling. Ever notice the fog you can make on a window by breathing on it? That’s water vapor leaving your body.
The biggest reason it’s bad to lose too much water is that the actual volume of your blood goes down. When blood volume goes down, blood pressure goes down. As blood pressure goes down, body heat goes up, because your blood helps regulate your core body temperature. Without enough blood, you can’t cool off. Pretty soon you overheat.
So various factors, from eating to circulatory health to the ambient temperature, play a part in how long you could go without water. Probably the biggest factor, though, is simply age: young people are much more likely to overheat faster than adults, which is why it’s especially important to keep an eye on the little ones on hot summer days.
如果從現(xiàn)在開始停止喝水，能活多久呢?
這涉及到很多方面的因素。人不是汽車，只需要一定量的汽油就行了。有時(shí)候，人體脫水一天便會(huì)死亡;但是有時(shí)，人體可以在脫水的情況下存活超過一個(gè)周。但是，任何人在脫水的情況下都不能長久的生存。
我們的身體不僅通過喝水獲得水，還通過吃飯。我們的身體通過排尿、出汗，甚至是呼吸將水排出體外。有沒有注意到自己往窗戶上呼氣形成的水霧呢?那就是從體內(nèi)排出的水蒸汽。
人體不能流失過多水分的最重要原因是因?yàn)闀?huì)導(dǎo)致人體實(shí)際血容量減少。當(dāng)血容量減少時(shí)血壓也會(huì)隨之降低。由于血液有助于調(diào)節(jié)人體溫度，因此當(dāng)血容量減少時(shí)，體溫便會(huì)升高。如果血容量不足，人體便無法冷下來，很快，就會(huì)熱得讓人受不了。
因此，從飲食到循環(huán)系統(tǒng)的健康再到環(huán)境溫度，眾多的因素決定了一個(gè)人在脫水的情況下能存活多久。但是，可能最重要的因素只是簡簡單單的——年齡：年輕人比成年人更快更容易過熱，這也就是為什么在炎熱的夏天要特別留神照顧小孩子了。
Note: exhale vt. 呼出
