医学英语综合教程第一单元.docxVIP

医学英语综合教程第一单元 Unite1 Structures of the Lung and the Kidney (肺和肾的结构) The Blood Vessels of the Lung （肺的血管结构） The lung receives its blood supply from two vascular systems―the bronchial and pulmonary circulations. The nutritive blood flow to all but the alveolar structures comes from the bronchial circulation, which originates from the aorta and upper intercostal arteries and receives about 1 per cent of the cardiac output. About one third of the venous effluent of the bronchial circulation drains into the systemic veins and back to the right ventricle. The remainder drains into the pulmonary veins and, along with the contribution from the Thebesian veins in the heart, represents a component of the 1 to 2 per cent right-to-left shunt found in normal subjects. 肺的血液供应来源于两套血管系统―――支气管循环和肺循环。来自支气管循环的营养血液分流到除肺泡外的所有结构，它来源于主动脉和上肋间静脉，还接受1%的心输出量。大约1/3的支气管循环系统的静脉输出量流入到全身静脉，然后回流到右心室。剩余的流入到肺静脉和心最小静脉，在正常的情况下一起形成1%?~2%自右向左风流。 The pulmonary arterial system runs alongside the airways from the hila（肺门）to the periphery. The arteries down to the level of the subsegmental airways (2-mm diameter) are thin-walled, predominantly elastic vessels. Beyond this, the arteries become muscularized until they reach diameters of 30μm, at which point the muscular coat disappears. Most of the arterial pressure drop takes place in these small muscular arteries, which are responsible for the active control of blood flow distribution in the lung. The pulmonary arterioles empty into an extensive capillary network and drain into thin-walled pulmonary veins, which eventually join with the arteries and bronchi at the hilum and exit the lung to enter the left atrium. 肺动脉循环系统沿着气道从肺门向外周分布。下行的亚节气道水平的肺动脉是薄而富有弹性的管道。从这儿开始，动脉呈肌型，直到其直径达30um，此时肌层消失。大多数的动脉压降发生在这些机型小动脉，对控制肺内的血流分布有作用。肺小动脉内的血流流入毛细血管网，进入薄璧的肺静脉。最终在肺门处与动脉和支气管伴行出肺入左心房。 2、什么是冠状动脉疾病？ 冠状动脉疾病发生于被称为脂质斑块的脂肪沉淀物在冠状动脉内形成时，冠状动脉环绕着心脏，并为它提供血液和氧气，当斑块形成时，会使动脉变窄并减少到达心脏的血液量，这会导致严重的问题，包括心肌梗塞 冠状动脉疾病（也称CAD）是心脏疾病中最常见的类型。在美国，它也是男性和女性的头号杀手。 当你发现自己