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
The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune
The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune
admin
2020-03-21
83
问题
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 communications network consisting of millions and millions of cells. Organized into sets and subsets, these cells pass information back and forth like clouds of bees swarming around a hive. 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 non-self. When immune defenders encounter cells or organisms carrying foreign or non-self molecules, the immune troops move quickly to eliminate the intruders. 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 non-self 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 passed during lactation, 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 non-self molecules in the sea of microbes in which we live. Learning entails producing the appropriate molecules and cells to match up with and counteract each non-self invader.
Any substance capable of triggering an immune response is called an antigen. Antigens are not to be confused with allergens, which are most often harmless substances ( such as ragweed pollen or cat hair) that provoke the immune system to set off the inappropriate and harmful response known as allergy. An antigen can be a virus, a bacterium, a fungus, a parasite, or even a portion or product of one of these organisms. Tissues or cells from another individual (except an identical twin, whose cells carry identical selfmarkers) 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, non-antigenic building blocks. An antigen announces its foreignness by means of intricate and characteristic shapes called epitopes, which protrude from its surface. Most antigens, even the simplest microbes, carry several different kinds of epitopes on their surface; some may even carry several hundred. 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 non-self and execute a misdirected immune attack. The result can be a so-called autoimmune disease such as rheumatoid arthritis or systemic lupus erythematosis. The painful side effects of these diseases are caused by a person’s immune system actually attacking itself.
After you have had the chicken pox, your immune system will be able to do all of the following EXCEPT ______.
选项
A、prevent your offspring from infection by the chicken pox virus
B、distinguish between your body cells and that of the chicken pox virus
C、remember previous experiences with the chicken pox virus
D、match up and counteract non-self molecules in the form of the chicken pox virus
答案
A
解析
推断题。根据题干可以定位到第二段。该段后半部分主要讲述了我们的免疫系统是如何防御入侵细胞的。选项[B][C][D]在文中均提到,只有[A]未涉及,因此正确答案是[A]。
转载请注明原文地址:https://kaotiyun.com/show/G6Y4777K
0
考研英语二
相关试题推荐
ManyAmericansregardthejurysystemasaconcreteexpressionofcrucialdemocraticvalues,includingtheprinciplesthatallc
Pricesarcsky-high,withprofitstomatch.Butlookingfurtherahead,theindustryfaceswrenchingchange,saysanexpertofen
Leadingdoctorstodayweighinonthedebateoverthegovernment’sroleinpromotingpublichealthbydemandingthatministersi
MillionsofAmericansandforeignersseeG.I.Joeasamindlesswartoy,thesymbolofAmericanmilitaryadventurism,butthat’
In1999,thepriceofoilhoveredaround$16abarrel.By2008,ithad【1】the$100abarrelmark.Thereasonsforthesurge【2】fro
ManyAmericansregardthejurysystemasaconcreteexpressionofcrucialdemocraticvalues,includingtheprinciplesthatallc
KimiyukiSudashouldbeaperfectcustomerforJapan’scar-makers.He’sayoung,successfulexecutiveatanInternet-servicesco
Menaregenerallybetterthanwomenontestsofspatialability,suchasmentallyrotatinganobjectthroughthreedimensionsor
Aneweconomicspaperhassomeold-fashionedadviceforpeoplenavigatingthestressesoflife:Findaspousewhoisalsoyourb
随机试题
既能化湿,又能行气的药物是
投诉的类型包括
下列喷锚暗挖掘进方式中,结构防水效果差的是()。
某机电工程采用EPC/交钥匙总承包的方式进行公开招标,并在国家发改委依法指定的媒体上发布了招标公告和资格预审公告。公告中明确说明了承包商报名时间及提供的资料;工程的基本情况;投标人需提交标书费用、押金、投标保函的要求;投标人获取和送达标书的方式、地点和起止
市场风险中,主要受通货膨胀预期、中央银行的货币政策、经济周期和国际利率水平等的影响的是()。
确定适当的汇率水平是汇率政策中最基础、最核心的部分。()
执行下面的程序流程图,输出S的值是()。
我国江西省中南部山区出现大片“红色荒漠”,即在亚热带湿润的岩溶地区,土壤遭受严重侵蚀,基岩裸露,地表呈现出类似荒漠化景观的土地退化现象。据此回答问题。“红色荒漠”形成的人为原因主要是()。
(1)在考生文件夹下的"samp1.mdb"数据库文件中建立表"tCourse",表结构如下:(2)根据表"tCourse"的结构,判断并设置主键。(3)设置"学时"字段的相关属性,使其输入的数据必须大于0。(4)设置"开课日期"字段的输入掩码为"
--Whydidyoucomesolate?--thebuswascrowded.We______waitingforhalfanhour.
最新回复
(
0
)