总觉得有点怪

The lungs’ primary purpose is gas exchange, and to achieve this with such efficiency almost the entire blood volume passes through the lungs during each circulation.This characteristic makes the lungs ideally suited to undertake many other important functions. The location of the lungs within the circulatory system is ideal for its role as a filter to protect the systemic circulation, not only from particulate matter but also from a wide range of chemical substances that undergo removal or biotransformation in the pulmonary circulation. The pulmonary arterial tree is well adapted for the reception of emboli without resultant infarction, and the very large area of vascular endothelium gives the lung a metabolic role out of proportion to its total mass. This large interface between the external atmosphere and the circulation is not without its own hazards, and the lung must protect the circulation from many potentially harmful inhaled substances.

肺的主要功能是气体交换，为有效气体交换，每次循环中几乎整个血容量都会通过肺。这一特性使得肺非常适合承担许多其他重要功能。肺在循环系统中的位置非常适合做循环系统的过滤器，不仅可过滤颗粒物，也可过滤肺循环中需要清除或生物转化的多种化学物质。肺动脉树易栓塞但不易梗死，极大的血管内皮面积使肺的代谢功能远超越其总质量相应的水平。外界大气与肺循环间的巨大界面存在其自身的危害，肺必须保护循环免受许多潜在有害吸入物的危害。

not only from particulate matter but also from a wide range of chemical substances that undergo removal or biotransformation in the pulmonary circulation. 也可过滤肺循环中需要清除或生物转化的多种化学物质