共用题干 Surgery Involving the Heart1 The heart-lung machine(pump-oxygenator)is ...

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问题共用题干 Surgery Involving the Heart

1 The heart-lung machine(pump-oxygenator)is a valuable addition to the modern operating room.
This machine has made it possible to perform many operations on the heart and other thoracic organs which
could not otherwise be done.There are several types of machines in use,all of which serve as a temporary
substitute for the patient's heart and lungs.
2 The machine siphons off the blood from the large vessels entering the heart on the right side so that
no blood passes through the heart and lungs.The blood is returned to the general circulation for body
distribution through one of the large arteries.While passing through the machine,the blood is oxygenated by
means of an oxygen inlet,and carbon dioxide is removed by various chemical means.These are the processes
that normally take place between the blood and the air in the lung tissue.While in the machine,the blood is
also deformed to be sure that all air bubbles are removed,since such bubbles could be fatal to the patient by
obstructing blood vessels.An electric motor in the machine serves as a pump during the surgical procedure to
distribute the processed blood throughout the body by means of the artery mentioned above.
3 Diseased valves may become deformed and scarred from endocarditis so that they are ineffective and
often obstructive.In some cases a special small knife can be inserted into the heart chamber and the valve
can be cut so that it no longer obstructs the blood flow. The valve may even become partially functional.In
other cases there may be so much damage that replacement is the only resort. Substitute valves,made of
plastic materials have proved to be a lifesaving measure for many patients.Very thin butterfly valves made of
dacron（涤纶）or other synthetic material have also been successfully used.
4 Artificial hearts or parts of hearts designed to assist the ventricles in their pumping function have not
proved as successful as the artificial valves.However,research continues and it is quite possible that an
effective device may soon be ready for use.More spectacular is the transplantation of a human heart from the
body of a person who has recently died.Tissues of the donor and the recipient should be as closely matched
as possible to avoid rejection by the recipient's antibody mechanism.This rejection syndrome is the most
serious problem related to heart transplants.

选项 The blood is oxygenated and carbon dioxide in it is removed________. A:and finally they fail to function properly B:to perform many surgical operations on the chest C:when it passes through the heart-lung machine D:and they no longer obstruct the blood flow E:to match tissues of the donor and the recipient F: when the ineffective valves are replaced by artificial ones

答案 C

解析第一段的主要内容在第二句，人工心肺机使许多心脏和其他胸部器官的手术成为可能，故选C。
第二段详细叙述了人工心肺机的工作原理，它是如何在手术期间代替心脏的功能的。
第三段讲述了心脏瓣膜的手术及其代用品。
第四段主要讲述了心脏移植及其代用品。
由文章第二段第三句“While passing through the machine, the blood is oxygenated by means of an oxygen inlet , and carbon dioxide is removed by various chemical means.”可知，血液在通过人工心肺机时得以充氧，同时，二氧化碳也被排出。
由文章第一段前两句可知，人工心肺机是胸部外科医生必不可少的助手。
由文章第三段第一句“Diseased valves may become deformed and scarred from endocarditis so that they are ineffective and often obstructive.”可知，心内膜炎会致使心脏瓣膜畸形，使其遭受创伤，以致失去正常功能，故选A。
文章最后两句表明，组织匹配是为了避免排异反应，它是心脏移植中最重要的事情。

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共用题干 Surgery Involving the Heart1 The heart-lung machine(pump-oxygenator)is ...

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