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
According to the American Academy of Dermatology, an estimated 10 to 50 million people in this country have an allergic reaction
According to the American Academy of Dermatology, an estimated 10 to 50 million people in this country have an allergic reaction
admin
2011-02-16
32
问题
According to the American Academy of Dermatology, an estimated 10 to 50 million people in this country have an allergic reaction to poison ivy each year. Poison ivy is often very difficult to spot. It closely resembles several other common garden plants, and can also blend in with other plants and weeds. But if you come into contact with it, you’ 11 soon know by the itchy, blistery rash that forms on your skin. Poison ivy is a red, itchy rash caused by the plant that bears its name. Many people get it when they are hiking or working in their garden and accidentally come into direct contact with the plant’s leaves, roots, or stems. The poison ivy rash often looks like red lines, and sometimes it forms blisters.
66.______
About 85 percent of people are allergic to the urushiol in poison ivy, according to the American Academy of Dermatology. Only a tiny amount of this chemical—1 billionth of a gram—is enough to cause a rash in many people. Some people may boast that they’ve been exposed to poison ivy many times and have never gotten the rash, but that doesn’t necessarily mean they’ re not allergic. Sometimes the allergy doesn’t emerge until you’ve been exposed several times, and some people develop a rash after their very first exposure. It may take up to ten days for the rash to emerge the first time.
67.______
Here are some other ways to identify the poison ivy plant. It generally grows in a cluster of low, weed-like plants or a woody vine which can climb trees or fences. It is most often found in moist areas, such as riverbanks, woods, and pastures. The edges of the leaves are generally smooth or have tiny "teeth". Their color changes based on the season—reddish in the spring; green in the summer; and yellow, orange, or red in the fall. Its berries are typically white.
68.______
The body’ s immune system is normally in the business of protecting us from bacteria, viruses, and their foreign invaders that can make us sick. But when urushiol from the poison ivy plant touches the skin, it instigates an immune response, called dermatitis, to what would otherwise be a harmless substance. Hay fever is another example of this type of response; in the case of hay fever, the immune system overreacts to pollen, or another plant-produced substance.
69.______
The allergic reaction to poison ivy is known as delayed hypersensitivity. Unlike immediate hypersensitivity, which causes an allergic reaction within minutes of exposure to an antigen, delayed hypersensitivity reactions don’t emerge for several hours or even days after the exposure.
70.______
In the places where your skin has come into contact with poison ivy leaves or urushiol, within one to two days you’ll develop a rash, which will usually itchr redden, burn, swell, and form blisters. The rash should go away within a week, but it can last longer. The severity of the reaction often has to do with how much urushiol you’ve touched. The rash may appear sooner in some parts of the body than in others, but it doesn’t spread—the urushiol simply absorbs into the skin at different rates in different parts of the body. Thicker skin such as the skin on the on soles of your feet, is harder to penetrate than thinner skin on your arms and legs.
A. Because urushiol is found in all parts of the poison ivy plant—the leaves, stems, and roots—it’ s best to a-void the plant entirely to prevent a rash. The trouble is, poison ivy grows almost everywhere in the United States(with the exception of the Southwest, Alaska, and Hawaii), so geography won’t help you. The general rule to identify poison ivy, "leaflets three, let it be, " doesn’t always apply. Poison ivy usually does grow in groups of three leaves, with a longer middle leaf—but it can also grow with up to nine leaves in a group.
B. Most people don’t have a reaction the first time they touch poison ivy, but develop an allergic reaction after repeated exposure. Everyone has a different sensitivity, and therefore a slightly different reaction, to poison ivy. Sensitivity usually decreases with age and with repeat exposures to the plant.
C. Here’ s how the poison ivy response occurs. Urushiol makes its way down through the skin, where it is metabolized, or broken down. Immune cells called T lymphocytes(or T-cells)recognize the urushiol derivatives as a foreign substance, or antigen. They send out inflammatory signals called cytokines, which bring
in white blood cells. Under orders from the cytokines, these white blood cells turn into macrophages. The macrophages eat foreign substances, but in doing so they also damage normal tissue, resulting in me skin inflammation mat occurs with poison ivy.
D. Poison ivy’ s cousinsr poison oak and poison sumac, each have their own unique appearance. Poison oak grows as a shrub(one to six feet tall). It is typically found along the West Coast and in me South, in dry areas such fields, woodlands, and thickets. Like poison ivy, die leaves of poison oak are usually clustered in groups of three. They tend to be thick, green, and hairy on both sides. Poison sumac mainly grows in moist, swampy areas in me Northeast, Midwest, and along the Mississippi River. It is a woody shrub made up of stems with rows of seven to thirteen smooth-edged leaflets.
E. The culprit behind die rash is a chemical in die sap of poison ivy plants called urushiol. Its name comes from the Japanese word "urushi, " meaning lacquer. Urushiol is me same substance that triggers an allergic reaction when people touch poison oak and poison sumac plants. Poison ivy, Eastern poison oak, Western poison oak, and poison sumac are all members of die same family—Anacardiaceae.
F. Call your doctor if you experience these more serious reactions:
Pus around die rash(which could indicate an infection).
A rash around your mouth, eyes, or genital area.
A fever above 100 degrees.
A rash mat does not heal after a week.
选项
答案
C
解析
接下来讲的是人体的免疫系统与毒藤之间的关系。毒藤会使人产生什么样的反应,该空紧接的就是毒藤过敏反应时如何产生的。“Here’s how the poison ivy response occurs.”一句承上启下。所以本题应选C。
转载请注明原文地址:https://kaotiyun.com/show/1KHd777K
本试题收录于:
公共英语五级笔试题库公共英语(PETS)分类
0
公共英语五级笔试
公共英语(PETS)
相关试题推荐
ImproveComputer-researchSkillsLikemanycollegestudents,JoseJuarezcarriesaroundapocket-sizedcomputerthatletshi
KobeBryantAfter10seasonswearingtheNo.8onhisback,KobeBryantwillbecomeNo.24nextseason.Thereasonforthes
DancingintheStreetsIfthereisonethingcertaintogetBraziliansontheirfeet,itistheRioCarnival(狂欢节).Heldin
Itissaidthehousesalongthisstreetwillsoonbedemolished
TrafficJams—NoEndinSight1.Trafficcongestion(拥堵)affectspeoplethroughouttheworld.Trafficjamscausesmogindozens
A.makingchildrenlaughB.almosteverythingC.alotofmoneyD.hischildhoodmemoriesE.tellingscarystoriesF.anumbero
Theorganizationwasboldenoughtofacethepress.
Letter-writing______.Thethirdparagraphsuggestedthat______.
Whatdoesthespeakermainlydiscuss?
Supermarketshoppershaveneverbeenmorespoiltforchoice.Butjustwhenwethoughttraditionalsystemsofselectivefarmingh
随机试题
下列说法哪一点是错误的
关于使用孕期保健手册的主要目的哪项正确
关于AB型血液正确的是
靶向给药系统是指利用载体将药物通过局部或全身血液循环而选择性地浓聚定位于靶组织、靶器官、靶细胞或细胞内结构的给药系统。()
内听道扩大为一侧内听道增宽超过
津液的输布和排泄障碍主要与哪几个内脏的功能失常有关
B公司是一家制造企业,2014年度财务报表有关数据如下:B公司没有优先股,目。前发行在外的普通股为1000万股。假设B公司的资产全部为经营资产,流动负债全部是经营负债,长期负债全部是金融负债。公司目前已达到稳定增长状态,未来年度将维持2014
EconomicRecoveryontheWayEconomicexpertsarepredictingthatthepoorlyperformingdomesticeconomywillrecoverinthe
(2017年广州)“开车不喝酒,喝酒不开车”是现在道路交通常用的标语。为保障交通安全,我国《刑法》对“酒后驾车”的相关情形也做了规定。在不考虑驾驶人年龄、行为能力等前提下,下列情形与刑法罪名对应关系正确的是()。
发送电子邮件时,邮件服务系统自动添加的邮件信息是()。
最新回复
(
0
)