The scientists observed that the more junk food the rats ate, the more they wanted to eat – a behavior very similar to that of rats addicted(上了癮的) to heroin, a dangerous drug. Johnson said the experiment shows that the brain chemistry of obesity(肥胖) and drug addiction may be quite similar.

In their experiment, Johnson and his team studied the “pleasure center” of rats’ brains. The pleasure center is a complicated network of nerve cells. If the animal exercises or eats, the cells reward the animal by releasing chemicals into the body that make it feel good. And when the body feels good, the animal – or person – will want to do the behavior again.

For the experiment, Johnson fed foods like cheesecake to one group of rats. Food like this is high in calories and fat. Another group of rats got a regular diet. The rats that ate junk food started to eat more and more.

“They’re taking in twice the amount of calories as the control rats,” says Paul Kenny, one of Johnson’s colleagues.

Kenny and Johnson wanted to know what was going on in the brains of these rats. They first designed a way to deliver a small electrical charge to the rats’ brains. This electrical charge would stimulate the pleasure centers to release pleasure-causing chemicals. The rats could control how much stimulation – and how much pleasure – they received by running on a wheel. The more the rat ran, the more pleasure it received.

The rats that had been eating junk food started running more and more. This behavior suggested that the junk-food-eating rats needed more brain stimulation to feel good compared with rats on a normal diet. In other words, their pleasure centers were becoming less sensitive and the junk food didn’t make them feel good unless they ate more and more.

Experiments like this one could help scientists understand how chemicals in the brain contribute to obesity. With that information, they may be able to help people avoid obesity in the first place.

(Note: Answer the questions or complete the statements in NO MORE THAN TEN WORDS.)

1.The scientists suggested it was actually ___________________ that made the rats feel good.

2.How did the scientist know what was happening in the brains of the junk-food-eating rats?

3.What was the purpose of the experiment mentioned in the article?

練習(xí)冊系列答案
相關(guān)習(xí)題

科目:高中英語 來源:2015-2016學(xué)年福建八縣一中高二上學(xué)期期中英語試卷(解析版) 題型:閱讀理解

H.T.B. Arts Center

FILM Tickets £2.50 / £ 1.50. Performances at 8 pm unless started otherwise.

WILD AT HEART 127mins.

Wen 6-Fri8 February

Director: David Lynch

Starring: Nicholas Cage, Laura Dern, Willam Dafoe. A first-class film. Cage and his girlfriend Dean are on the run through the dangerous Deep South. They are hiding from gunmen who have been hired to kill Cage by Dean's mother. Victims, yes—but they also have fun. It's wild at heart, strange on top. Funny, frightening and brilliant.

DICK TRACY 113mins

Mon 11-Sat16 February 6pm

Tickets on sale 5-6 pm

Director: Warren Beatty

Starring: Warren Beatty , Madonna The famous detective tries to stop Big Boy and the Blank from taking over the city. A colorful and exciting film. Some parts are frightening, so think twice about taking children.

BATMAN 126mins

Mon11-Sat16 February 8.30pm

Tickets on sale 7.30-8.30pm

PIZZA PLUS offer 6-7pm

Director: Tim Burton

Starring: Michael Keaton, Jack Nicholson. A few essential questions must be asked...Is Batman a mad hero? Why does Bruce Wayne spend millions dressing up as a bat? Has Nicholson's Joker stolen the whole movie? Great action and excellent acting, especially by Nicholson.

1.We know from Wild at Heart that

A. Wild at Heart is funny rather than frightening

B. Cage was not accepted by his future mother-in-law.

C. A famous detective happened to help Cage and Dean.

D. Cage and Dean are playing the hide-and-seek game with Dean’s mother.

2.According to the text, we can learn that _____.

A. Batman has the longest running time

B. One can buy tickets in advance for all the films

C. You’d better not take your children with you to see Dick Tracy

D. While watching Batman one can enjoy pizza at 7:30 pm.

3.Where can we most probably read this text?

A. In a movie review.

B. In an ad page.

C. In a short story.

D. In an introduction of an art center.

查看答案和解析>>

科目:高中英語 來源:2016屆重慶市高一下學(xué)期期末考試英語試卷(解析版) 題型:其他題

課文填空(共5小題:每小題1分,滿分5分)

Mao Zedong wrote a poem in which he dreamed of “walls of stone to 1. back clouds and rain till a2. lake rises in the 3. gorges”. Now his dream has come 4.. The power of the Yangtze River, which is the world’s third 5.river, has been harnessed by the Three Gorges Dam.

查看答案和解析>>

科目:高中英語 來源:2016屆重慶市高一下學(xué)期期末考試英語試卷(解析版) 題型:單項填空

—I’m worried about the coming test!

—______, you can do it!

A. Don’t mention it B. come on

C. Well done D. Not likely

查看答案和解析>>

科目:高中英語 來源:2016屆重慶市高一下學(xué)期期末考試英語試卷(解析版) 題型:單項填空

It is quite warm _________January in Chongqing.

A. to B. with

C. in D. for

查看答案和解析>>

科目:高中英語 來源:2016屆上海寶山區(qū)吳淞中學(xué)高一上第一次月考英語試卷(解析版) 題型:單項填空

The experienced teachers try their best _____ the younger ones _____experience.

A. to help…getting

B. help…get

C. to help…to get

D. helping…get

查看答案和解析>>

科目:高中英語 來源:2016屆陜西西安市高一下學(xué)期期末考試英語試卷(解析版) 題型:信息匹配

A.Means of e?waste recycling

B.How e?waste comes into being

C.The benefit of e?waste recycling

D.The technologies of e?waste recycling

E.The importance of the electronic waste recycle

F.Modern technology brings convenience and e?waste

1.

Modern technology does bring us many conveniences(便利),from Wi?Fi(無線網(wǎng)絡(luò))enabled cell phones and ever? smaller laptop computers that make entire lives easy to energy? efficient washers that use half the power and time to complete their tasks. However,these new toys and equipment finally become electronic waste ( 電子垃圾)(e? waste)once they are out of use.

2.

E? waste includes everything from empty printer ink containers to broken refrigerators. As people buy new items to replace aging electronics or make upgrades(升級),more electronic waste comes into being. In some cases,such as 2009's switch from analog(模擬)to digital television broadcasting in the United States,changes in technology are so great that old equipment may not even work at all with new systems.

3.

There are many reasons why it is important to recycle electronic waste. Much of the material used to construct electronics,including metal and plastic parts,can be recycled into new items at a discount of the cost and energy use needed to create things from new raw materials(原材料). Additionally,many electronics contain poisonous substances (有毒物質(zhì))that are harmful to the environment and could be deadly if they go into an area's groundwater. When properly recycled,they can be reused and will not do harm to the environment. Because of these environmental concerns,many areas require by law that electronic waste be properly recycled.

4.

The availability(可用性)of e?waste recycling programs varies from place to place. In some areas,annual collections are held once or twice a year as a means of dealing with e?waste as well as used engine oil or other waste that is harmful to the environment. There are also some good alternatives (替代品) to recycling your e?waste. Any items that are in working condition can be given to friends or donated to charities(慈善機構(gòu))like Goodwill or the Salvation Army,who rely heavily on donations ( 捐贈) . Freecycling ,or passing on your unwanted items to those in need of them,is also a means of finding new homes for used items.

5.

E?waste recycling helps protect the environment by reducing the amount of poisonous materials placed in landfills(垃圾場)and saving recyclable parts to save energy and other resources. Recycling is a way of life. Stick to that choice every single day and recycling will become second nature to us.

查看答案和解析>>

科目:高中英語 來源:2016屆安徽師大附中高一下學(xué)期期中考試英語試卷(解析版) 題型:其他題

Studying Abroad

Nowadays, studying abroad gains popularity in China. Many rich parents would rather send their children abroad to receive education than let them be educated in China.

As every coin has two sides, studying abroad is not an exception. There are advantages for people to attend schools abroad. In the first place, he can use the foreign language in his daily life so that his ability in the second language may be greatly improved, as it is obvious that there is no better chance to improve second language than living in the country where it is spoken. While studying in a foreign country, he will most likely meet many others from overseas and it is possible to make friends from all over the world. This is not only exciting on the social level, but could lead to important overseas contacts in his career as well. He can get familiar with the latest knowledge in science and make use of the first? rate facilities available. In this way, there is every chance that he is able to widen his horizon (眼界) and broaden his mind.

Of course, attending schools abroad may bring about a series of problems. The most serious problem is language barrier. Most of the students who go abroad don’t have enough skills in the language spoken there. As a result, on arriving there, they will find it difficult to understand what the teachers say. Besides, for lack of knowledge of the customs of the local people, they may constantly run into trouble in dealing with various situations.

Therefore, given an opportunity to attend a school abroad, one must consider both sides of the factors carefully before making up his mind.

Title: Studying Abroad

Phenomenon

Sending children abroad to receive education is 1. with many rich parents.

Advantages

● Children have the best 2. to improve the second language because they can use it 3..

● They can make friends with other students from 4..

● They can 5. the latest

knowledge in science and have access to the

best facilities.

6.

● Language barrier is the number one problem. Because students are not 7. at the language spoken there,they will have difficulty in 8. what the teachers say.

● It is not easy for them to deal with

cross-cultural munication9.to lack of knowledge of the customs of the locals.

Conclusion

Both sides of the factors should be 10. carefully before one makes a decision.

查看答案和解析>>

科目:高中英語 來源:2015屆安徽師大附中高二下學(xué)期期中考試英語試卷(解析版) 題型:單項填空

Only when he told me________what trouble he was in.

A.did I realize B.I realized

C.do I realize D.I realize

查看答案和解析>>

同步練習(xí)冊答案