We talked last week about the life of famed heart doctor Michael DeBakey. He died this month at age ninety-nine.Today, we talk about the object of his work. The heart is a complex organ that starts beating a few weeks after conception. At this point the heart is a tube. In the coming days, it grows and bends into the shape of the heart.
上周我们介绍了著名心脏病医生Michael DeBakey的生平。他在本月去世，享年99岁。今天我们来谈谈他所从事的工作。心脏是一个非常复杂的器官，它从受精几周后就开始跳动。这时的心脏呈管状。在接下来的日子里，它不停的成长、弯曲，形成了心脏最终的形状。

Later, it divides into four parts. As the heart beats, it pumps blood through these chambers and the blood vessels in the body. The body is estimated to have at least ninety-six thousand kilometers of blood vessels.
接下来，它会分裂成四个部分。当心脏跳动时，它将血液泵入这些心室以及身体内的血管。据估计，人的全身有至少9万6千公里长的血管。

That is about the same as two and a half times around the Earth. But blood goes the distance in about twenty seconds on its way back to the heart. Each day the heart pumps about eight thousand liters of blood.
这个长度可以绕地球两周半。但是血液在大约20秒内就会回到心脏。每天心脏会泵出约8千公升血液。

The blood feeds the brain and other organs with oxygen and nutrients. It also carries away carbon dioxide and other waste.The heart pumps by expanding and contracting of muscle. In a healthy adult, the heart beats an average of seventy-two times a minute -- about one hundred thousand times a day.
血液将氧气和营养物质带给大脑和身体的其它器官。同时带走二氧化碳和废物。心脏是通过伸缩肌肉来完成泵血的动作的。一个健康的成年人的心跳约为每分钟72跳，每天约10万次。