The Mini.docVIP

The Mini-Lecture of TEM8 1. Camel A camel can travel hundreds of miles, over several days, without stopping to drink. On todays Moment of Science, we’ll learn how camels survive the dry desert. Let’s start with the hump. Contrary to what you might have heard, camels do not store extra water here. The hump stores fat, providing energy for their long, desert trek. This fat, however, can help keep a camel from getting thirsty. As the fat is burned, water is produced as one of the byproducts. This extra water enters the camel’s bloodstream to add to its water supply. Camels conserve water by not sweating as much as we do. A camel’s metabolism lowers at night, making its body temperature much lower than a human’s. Because we sweat to cool ourselves off, starting with a lower body temperature means less need to sweat. Camels are also covered with heavy fur which keeps the daytime heat out. Because it’s so good at keeping its cool, a camel can travel a long way without sweating very much. Camels are also good at maintaining their blood volume. Once we humans lose about twelve percent of our body’s water, our blood becomes too thick to work properly. A camel’s blood, however, stays more or less consistent, allowing the camel to lose up to twenty-five percent of its weight by dehydration. Another thing that helps a camel conserve water is its nasal passages. When we exhale, we loose a lot of water vapor, as any fogged up car window will prove. Camels have extra dry nasal passages which actually recondense the water out of each breath, allowing much less to escape. As you can see, there is no single explanation for a camel’s desert survival abilities. Instead, a camel draws on a whole range of adaptations. 译文： 骆驼可以行走数百英里，并在几天之内也不用喝水。 在今天的科学一刻中，我们将会学习骆驼是怎样在干燥的沙漠中生存的。 我们先从驼峰说起，和你所听说的不一样的是，骆驼并没有储存多余的水在这里。驼峰积聚着脂肪，为它们长距离的沙漠旅行提供能量。然而就是这些脂肪，可以帮助骆驼止渴。水就是这些脂肪燃烧所产生的副产物之一。这些额外的水进入骆驼的血液，增加其水分的供应。 骆驼不像我们那样出汗，这样也可以储存水分。骆驼的新陈代谢到晚上就会降低，让它的体温低于人类。出汗可以冷却我们自己，因此如果体温较低的话，对汗水的需求也会比较少。骆驼同样覆盖着厚重的皮毛