论文部分内容阅读
经过不断演化而形成的循环系统,为了完成它的正常生理使命,必须流经许多肉眼看不见的血管即毛细血管。它们的实际长度在人每磅肌肉内有450英里,其中每天参加反复循环的血量达15加仑。正是这些血管,使人获得健康或者罹病,因为人体组织在此进行营养交换和废物排泄;血压的作用又沿着这些血管产生,并且决定着是否有卒中或心脏病发作的可能性。较大的可见血管,即所谓动脉和静脉,二者并非决定血压的重要因素。它们反而是赖以快速输送血液的自由干道,除了意外事故或血栓栓塞等,发生在这些大血管部分的问题较少。
The circulatory system, which has evolved and evolved, must flow through many blood vessels, the capillaries, which are invisible to the naked eye, in order to fulfill its normal physiological mission. Their actual length is 450 miles per pound of muscle in humans, of which 15 gallons of blood per day participate in repeated cycles. It is these blood vessels that make people healthy or diseased because of the exchange of nutrients and the excretion of waste by human tissues; the effects of blood pressure are taken along these blood vessels and determine the likelihood of a stroke or a heart attack. Larger visible blood vessels, so-called arteries and veins, are not an important determinant of blood pressure. Instead, they are free lanes on which blood can be delivered rapidly, and fewer problems occur in these large blood vessel sections, except for accidents or thromboembolism.