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
外语
Immune Functions The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The s
Immune Functions The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The s
admin
2011-04-15
65
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 sen 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 (过敏原), 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.
Which of the following statements is true? ______
选项
A、Allergens are usually harmful substances.
B、Antigens can trigger an immune response.
C、People with antigens do not suffer from obvious responses.
D、There is no difference between an antigen and an allergen.
答案
B
解析
本题有一定难度, 需要吃透原文句意。答案依据在文章最后一段第一句:Any substance capable of triggering an immune response is called an antigen(抗原).回来看选项, 很明显, B项符合原文句意, 是答案。
转载请注明原文地址:https://kaotiyun.com/show/fZmd777K
本试题收录于:
职称英语卫生类A级题库职称英语分类
0
职称英语卫生类A级
职称英语
相关试题推荐
Sharingtasksanddecisionsinthehomeleadsto______.Thedangerinthesharingofhouseholdtasksbythemotherandfather
HowtheBodyKeepstheSameTemperatureThetemperatureofyourbodyshouldbealwaysjustthesame,nomatterwhetherthewe
Ifeelregretaboutwhat’shappened.
Techniquestoharnesstheenergyofthesunarebeingdeveloped.
FriendsMayBeKeytoLivingLongerLookingforthesecretofalonglife?Lookcloselyatyourfriends.Newresearchsugges
Anewsystemofqualitycontrolwasbroughtintoovercomethedefectsinthefirm’sproducts.
Acupofwholemilkprovidesroughlyonehundredsixty-sixcaloriesofenergy.
Andersonleftthetable,remarkingthathehadsomeworktodo.
WhereHaveAlltheBeesGone?Scientistswhostudyinsectshavearealmysteryontheirhands.Allacrossthecountry,honey
NewU.S.PlanforDiseasePreventionUrgingAmericanstotakeresponsibilityfortheirhealth,HealthandHumanServicesSe
随机试题
下列关于按钮的说法中错误的是:
CPU是可编程序控制器的核心组成部分,承担接收、处理信息和组织整个控制工作。()
镰状红细胞贫血是由于血红蛋白β链第6位的哪种改变造成的
关于经济与社会发展规划所起的作用,下列描述有误的是()。
某施工单位于2006年5初开工建设某二级公路,正遇上梅雨季节,为确保工期和质量,施工单位的技术人员精心编制了施工组织设计,包含如下内容:(1)开挖多条排水沟作为临时排水设施;(2)对K0+000~K0+850段填方路堤的原地基进行处理;(3)对
某拟建水厂的原水为浊度小于3:3mg/1河流水,水质稳定,下列给水处理工艺流程中()应为首选。
中共十八届四中全会通过的《中共中央关于全面推进依法治国若干重大问题的决定》提出,全面推进依法治国,总目标是()。
阅读下列材料,回答问题。材料一晋永嘉大乱,幽、冀、青、并、兖州及徐州之淮北流民,相率过淮,亦有过江在晋陵郡界者。
幼儿园必须切实做好幼儿心理和生理卫生保健工作。()
某城市考上大学的学生中,女生的比例比男生高。根据这个事实,王老师认为本市女生学习比男生好。以下哪项最能削弱王老师的结论?()
最新回复
(
0
)