首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
考研
A. The consequence of losing bones B. A better lab than on earth C. Two different cases D. Multiple effects form wei
A. The consequence of losing bones B. A better lab than on earth C. Two different cases D. Multiple effects form wei
admin
2011-02-12
151
问题
A. The consequence of losing bones
B. A better lab than on earth
C. Two different cases
D. Multiple effects form weightlessness
E. How to overcome weightlessness
F. Factors that are not so sure
During weightlessness, the forces within the body undergo dramatic change. Because the spine is no longer compressed, people grow taller. The lungs, heart and other organs within the chest have no weight, and as a result, the rib cage and chest relax and expand. Similarly, the weights of he liver, kidneys, stomach and bowels disappear. One astronaut said after his flight: "You feel our guts floating up. I found myself tightening my belly, sort of pushing things back."
41.______
Meanwhile muscles and bones come to be used in different ways. Our muscles are designed to support us when stand or sit upright and to move body parts. But in space, muscles used for support on the ground are no longer needed for that purpose; moreover, the muscles used for movement around a capsule differ from those used for walking down a hall. Consequently, some muscles rapidly weaken. This doesn’t present a problem to space travelers as long as they perform only light work. But preventing the loss of muscle tissue required for heavy work during space walks and preserving muscle for safe return to Earth are the subject of many current experiments.
Studies have shown that astronauts lose bone mass from the lower spine, hips and upper leg at a rate of about 1 percent per month for the entire duration of their time in space. Some sites, such as the heel, lose calcium faster than others. Studies of animals taken into space suggest that bone formation also declines.
42.______
Needless to say, these data are indeed cause for concern. During space flight, the loss of bone elevates calcium levels in the body, potentially causing kidney stones and calcium crystals to form in other tissues. Back on the ground, the loss of bone calcium stops within one month, but scientists do not yet know whether the bone recovers completely: too few people have flown in space for long periods. Some bone loss may be permanent, in which case ex-astronauts will always be more prone to broken bones. 43.______
These questions mirror those in our understanding of how the body works here on Earth. For example, elderly women are prone to a loss of bone mass. Scientists understand that many different factors can be involved in this loss, but they do not yet know how the factors act and interact; this makes it difficult to develop an appropriate treatment. So it is with bone loss in space, where the right prescription still awaits discovery.
44.______
Many other body systems are affected directly and indirectly. One example is the lung. Scientists have studied the lung in space and learned much they could not have learned in laboratories on earth. On the ground the top and bottom parts of the lung have different patterns of air flow and blood flow. But are these patterns the result only of gravity, or also of the nature of the lung itself? Only recently have studies in space provided clear evidence for the latter. Even in the absence of gravity, different parts of the lung have different levels of air flow and blood flow.
45.______
Not everything that affects the body during space flight is related solely to weightlessness. Also affected, for example, are the immune system and the multiple systems responsible for the amount and quality of sleep (light levels and work schedules disrupt the body’s normal rhythms). Looking out the spacecraft window just before going to sleep (an action difficult to resist, considering the view) can let enough bright light into the eye to trigger just the wrong brain response, leading to poor sleep. As time goes on, the sleep debt accumulates.
For long space voyages, travelers must also face being confined in a tight volume, unable to escape, isolated from the normal life of Earth, living with a small, fixed group of companions who often come from different cultures. These challenges can lead to anxiety, depression, crew tension and other social issues, which affect astronauts just as much as weightlessness—perhaps even more. Because these factors operate at the same time the body is adapting to other environmental changes, it may not be clear which physiological changes result from which factors. Much work remains to be done.
选项
答案
B
解析
比地球上更好的实验室。文章第6段前两句话的大意是:身体的很多其他系统也会直接或间接地受到影响,例如人体的肺脏。科学家在太空对人体的肺脏进行了研究并获得了地面实验室中得不到的许多成果。由此可认定与小标题B相匹配,因此选项B为本段的最佳标题。
转载请注明原文地址:https://kaotiyun.com/show/Z3e4777K
0
考研英语二
相关试题推荐
Weshouldconcentrateonsharplyreducinginterestratestopulltheeconomyoutof______.
ManyAmericansregardthejurysystemasaconcreteexpressionofcrucialdemocraticvalues,includingtheprinciplesthatallc
Overthepastdecade,manycompanieshadperfectedtheartofcreatingautomaticbehaviors-habits-amongconsumers.Thesehabits
IwasaddressingasmallgatheringinasuburbanVirginialivingroom-awomen’sgroupthathadinvitedmentojointhem.Through
Asia’srealboat-rockerisagrowingChina,notJapan,aseniorAmericaneconomistobserved.Thereissomuchnoisesurround
Nameshavegainedincreasingimportanceinthecompetitiveworldofhighereducation.Ascollegesstriveformarketshare,they
OlympicGamesareheldeveryfouryearsatadifferentsite,inwhichathletes【1】differentnationscompeteagainsteachotherin
LOSANGELES—Allyear,Hollywoodexecutiveshavebeenbrushingasideworriesaboutbox-officestagnationintheUnitedStatesand
随机试题
指导病人正确服用硝酸甘油以缓解心绞痛的方法是( )
链激酶用于治疗血栓性疾病,是由于()
循环系统实现体温调节的主要途径是
李女十,有肺癌病史。现诊断怀疑肿瘤转移至胸膜内,其胸水外观应为
市场经济亦可指以()作为配置资源的经济运行形式或经济管理体制。
某企业110kV变电站直流系统电压110V,采用阀控式密闭铅酸蓄电池组,无端电池,单体电池浮充电压2.23V,直流系统不带降压装置,充电装置采用一组20A的高频开关电源模块若干个,站内控制负荷、动力负荷合并供电。请回答下列问题:假定充电装置额定电流为1
国家秘密及其密级的具体范围,由()分别会同外交、公安、国家安全和其他中央有关机关规定。
根据《水利水电工程启闭机制造、安装及验收规范》DL/T5019一1994,当负荷达到()额定启闭力时,复合式负荷控制器应自动切断主回路和报警。
教育心理学研究的核心内容是学习过程,如学习的实质、条件、动机、迁移以及不同种类的学习的特点。()
Youarewhatyoueat,orsothesayinggoes.ButRichardWrangham,ofHarvardUniversity,believesthatthisistrueinamorep
最新回复
(
0
)