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
30
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
从12、13岁起至成年的行为发展阶段属于 A.被动发展阶段 B.主动发展阶段
活动资源估算的输出不包括()。
根据操作风险引起原因的不同,操作风险可以分为由()所引发的风险。
()是企业的萌芽形态。
关于慢性阻塞性肺病的主要发病因素,下列哪一项是错误的
海关对进口货物实施估价必须征得纳税义务人的同意。()
五志中属于“木”的是A.怒B.喜C.思D.悲E.恐
《物业管理条例》确立的基本法律关系包括()。A.供水、供电等单位与开发企业的关系B.业主相互之间的关系C.业主与物业服务企业之间的关系D.开发企业与业
物证、档案、鉴定结论其证明力一般大于()。A.勘验笔录和经过公证、登记的书证B.视听资料和证人证言C.勘验笔录、证人证言D.经过公证、登记的书证和视听资料
H银行2009年初对国内整个房地产行业贷款5000万元,后由于我国房市震荡,H银行无法按期收回贷款,该风险属于( )。A.经营风险B.行业风险C.区域风险