首页
财务会计
医药卫生
金融经济
考公考编
外语考试
学历提升
职称考试
建筑工程
IT考试
其他
登录
职称考试
Immune Functions The immune system is equal in complexity to the combined i...
Immune Functions The immune system is equal in complexity to the combined i...
admin
2020-12-24
31
问题
Immune Functions
The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune system in defending the body relies on a dynamic regulatory communication network consisting of millions and millions of cells. Organized into sets and subsets,these cells pass information back and forth like clouds of bees flying around a hive (蜂巢). The result is a sensitive system of checks and balances that produces an immune response that is prompt,appropriate,effective,and self-limiting.
At the heart of the immune system is the ability to distinguish between self and nonself. When immune defenders encounter cells or organisms carrying foreign or nonself molecules,the immune troops move quickly to eliminate the intruders (入侵者). Virtually every body cell carries distinctive molecules that identify it as self. The body’s immune defenses do not normally attack tissues that carry a self-marker. Rather,immune cells and other body cells coexist peaceably in a state known as self-tolerance. When a normally functioning immune system attacks a nonself molecule,the system has the ability to “remember” the specifics of the foreign body. Upon subsequent encounters with the same species of molecules,the immune system reacts accordingly. With the possible exception of antibodies (抗体)passed during lactation (授乳期), this so called immune system memory is not inherited. Despite the occurrence of a virus in your family, your immune system must “learn” from experience with the many millions of distinctive nonself molecules in the sea of microbes (微生物)in which we live. Learning entails producing the appropriate molecules and cells to match up with and counteract each nonself invader.
Any substance capable of triggering an immune response is called an antigen (抗原).Antigens are not to be confused with allergens (过敏源),which are most often harmless substances that provoke the immune system to set off the inappropriate and harmful response known as allergy. An antigen can be a virus, a bacterium, or even a portion or product of one of these organisms. Tissues or cells from another individual also act as antigens; because the immune system recognizes transplanted tissues as foreign, it rejects them. The body will even reject nourishing proteins unless they are first broken down by the digestive system into their primary, nonantigenic building blocks. An antigen announces its foreignness by means of intricate and characteristic shapes called epitopes (抗原表位), which protrude (突出)from its surface. Most antigens,even the simplest microbes,carry several different kinds of epitopes on their surface; some may even carry several hundreds. Some epitopes will be more effective than others at stimulating an immune response. Only in abnormal situations does the immune system wrongly identify self as nonself and execute a misdirected immune attack.
The immune cells and other cells in the body coexist peaceably in a state known as
选项
A. balance.
B. harmony.
C. tolerance.
D. self-tolerance.
答案
D
解析
第二段中间说,“免疫细胞与身体其他细胞在自我耐受的状态下和平共处。
转载请注明原文地址:https://ti.zuoweng.com/ti/Z29QKKKQ
相关试题推荐
Theyaretryingtoidentifywhatiswrongwiththepresentsystem.A:proveB:dis
Theinterstatehighwayssystemprovidesaccessbetweenmajormilitaryinstall...
共用题干 第二篇RailroadSupersystemInrecentyears,railroadshavebeencombiningwi...
共用题干 第二篇RailroadSupersystemInrecentyears,railroadshavebeencombiningwi...
共用题干 第二篇StarQualityAnewanti-cheatingsystemforcountingthejudges'sco...
共用题干 第二篇StarQualityAnewanti-cheatingsystemforcountingthejudges'sco...
Before1950theWeatherBureauhadnospecialsystemfornaminghurricanes.A:sto
Wehavetoactwithintheexistinglegalframework.A.limitB.systemC.procedu
ImmuneFunctions Theimmunesystemisequalincomplexitytothecombinedi...
ImmuneFunctions Theimmunesystemisequalincomplexitytothecombinedi...
随机试题
某慢性阻塞性肺疾病患者,护士指导其进行呼吸训练,下列不正确的是
某工程有甲、乙、丙、丁四个实施方案可供选择。四个方案的投资额依次是60万元、80
请从所给的这几个选项中,选择最合适的一个填在问号处,使之呈现一定的规律:
“四个回归”背景下辅导员应如何提升思政工作能力?
根据《节约能源法》的规定,对固定资产投资项目国家实行:A.节能目标责任制和节能考核评价制度B.节能审查和监管制度C.节能评估和审查制度D.能源统计制度
关于股票基金的风险管理,以下说法不正确的是()。A.股票基金可以通过分散投资降低系统性风险B.股票基金相对于混合基金、债券基金与货币基金,风险最高C.
溶血对血清中的酶活性影响最大的是A:LPSB:LDC:ASTD:AMYE:ALT
委托工程监理是业主在工程()阶段的工作。A:设计B:施工安装C:建设准备D:生产准备
货物招标文件中的投标人须知是对投标人的具体要求,一般不包括()A、符合招标文件的声明B、询价函C、技术说明D、货物采购单及其附件
共用题干 GoingonaDietAtypicalpersonneedsabout1,800caloriesperdaytos...