人體大探索:人爲什麼會出臭汗?
What's sweat?
什麼是汗水？
Your body works best when its temperature is about 37? Celsius. When your body gets hotter than that, your brain doesn't like it — it wants your body to stay cool. So the part of your brain that controls temperature, called the hypothalamus, sends a message to your body, telling it to sweat.
人體體溫在37攝氏度時，身體各功能活動最佳。當體溫超過這個溫度時，大腦就不樂意了，它要讓體溫降下來。所以大腦中控制體溫的部分下丘腦就會發出一個信號給身體，告訴它要排汗。
Then special glands in your skin called sweat glands start making sweat. Sweat is also known as perspiration, and it is made almost completely of water, with tiny amounts of other chemicals like ammonia, urea, salts, and sugar.
人體皮膚中有種特別的腺體叫汗腺，負責分泌汗液。汗液幾乎全是由水組成，也含有微量的化學元素，包括氨、尿素、鹽和糖。
The sweat leaves your skin through tiny holes called pores. When the sweat hits the air, the air makes it evaporate. As the sweat evaporates off your skin, you cool down.
汗液通過皮膚上的小孔即毛孔排放出來。當汗液和空氣接觸之後，就會蒸發。汗水一旦蒸發，人體的體溫就會降下來。
Sweat is a great cooling system, but if you're sweating a lot on a hot day, you could be losing too much water. Then you need to put liquid back in your body by drinking plenty of water so you won't get dehydrated.
出汗是很好的降溫系統。但是，如果你在天熱的時候出了很多汗，你就可能流失過多的水分。這時，你就需要通過大量喝水來補充體內水分，不然你就會脫水。
Why does sweat smell? Sweat by itself doesn't smell at all. It's the bacteria that live on your skin that mix with the sweat and give it a stinky smell. And when a person reaches puberty, special hormones affect the glands in the armpits — these glands make sweat that can really smell.
那麼，汗水爲什麼會有味道呢？汗水本身是沒有味道的。但皮膚中的細菌和汗水結合起來就會產生一種臭味。當人到了青春期之後，就會在腋窩的汗腺中產生一種特殊的激素，使得汗水聞起來有種汗臭味。
詞彙點津：
sweat glands 汗腺
