【英语语言学习】关于我们的头发

This is SCIENCE IN THE NEWS in VOA Special English. I’m Barbara Klein. And I’m Steve Ember.

 

Today we talk about hair. We will tell what hair is, how it grows, and some of the main reasons people lose it.

 

Hair has always been an important sign of beauty. This is especially true for women. Next to the face, hair is one of the main qualities people look for when they consider a woman’s beauty. Whether long or short, curly¹ or straight, hair often gets a lot of attention. People who have it value it. Those of us who do not, often mourn its loss.

 

Each hair on a person’s head grows from a single tube-like hole in the skin called a follicle. People are born with all of the hair follicles they are ever going to have. The average person has about 100,000 hair follicles. They begin to form on a fetus² around the third month of pregnancy³.

 

The part of the hair under the skin is known as the hair root. The hair sticking out from the skin is known as the hair shaft⁴. The shaft is made up of dead cells that have been pushed up through the root. At the base of the hair root is a small ball-like formation called a bulb. This is where new cells are formed. These cells receive nutrition from the blood supply under the skin.

 

As new cells form, the older cells are pushed up through the root. In time, the old cells are cut off from the blood supply and begin to form a hard protein called keratin. Keratin is the same protein found in our skin and nails. These dead cells and keratin are what make up the hair shaft. This whole process is what causes hair to grow.

 

Each hair grows independently of other hairs. There are three periods of hair growth. Not all hairs experience the same period of growth at the same time. The period of active growth is called Anagen. During this period, hair grows at a rate of about 3/10 millimeters a day, or one centimeter a month. About 85% of hair follicles are going through this process at any given time. This period can last from two to six years.

 

The Catagen period of hair growth comes next. It is then that hair growth begins to slow down. This period usually lasts two or three weeks. Finally, hair growth comes to a complete stop and the hairs begin to fall out. This period is known as telogen. It affects about 15% of all hairs at a time.

 

On average, a person loses between 50 and 100 hairs every day. Since each hair grows at a different rate, this process is overlooked⁵. Once the telogen period has ended, the hair growth process begins again.

 

So what happens when a person has trouble growing hair or suffers from hair loss? Your genes⁶ control how fast or how long your hair will grow. Some people have a longer than usual anagen growth period. These people may be able to grow more hair than the average person. However, others struggle to grow shoulder-length hair. These people have a shorter than normal anagen period.

 

Your health can also affect hair growth. Poor nutrition can cause some hair follicles to stop growing or cause the hairs that grow to become weak or thin. Problems with hair growth can result from thyroid problems or other conditions like anemia⁷, diabetes⁸ and lupus. Health experts say people who experience a sudden increase in hair loss should seek medical advice.

 

Some hair loss can result from a combination of genetics, aging and hormones¹⁰. When this happens, the hair growth cycle changes and the hair follicles get smaller. In addition, the hairs may get thinner and shorter. Soon the hairs stop growing completely on some parts of the head. People with this condition usually have family members who have experienced similar hair losses. This kind of hair loss is known as pattern baldness. It is the most common kind of hair loss. The official medical term for the condition is androgenetic alopecia.

 

The Latin word alopecia means loss of hair or baldness. It is also the term used to describe the medical condition that results in the loss of hair. Alopecia areata is the second most common form of hair loss after pattern baldness. It is the most common form of autoimmune disease. In alopecia areata, the body’s defenses against disease attack the hair follicles, resulting in a loss of hair on the scalp and other parts of the body.

 

The condition usually begins with small round areas of hair loss on the scalp. When hair loss takes place over the whole surface of the scalp, it is called alopecia areata totalis. Sometimes a person may lose their eyebrows¹¹, eyelashes or hair on other parts of the body. This condition is called alopecia areata universalis. It is the rarest form of alopecia.

 

The National Alopecia Areata Foundation says alopecia areata affects about 2% of the population. About five million people in the United States have the condition. It affects people of all ages and races, and often begins in childhood.

 

That was true of 22 year old Kayla Martell, the winner of the Miss Delaware Pageant¹² last year. Ms. Martell began losing her hair when she was about ten years old. By the time she was thirteen, all of her hair had come out.

 

Kayla Martell began competing in beauty pageants¹³ around that same time. In many of the events, she competed without hair. In fact, three of the five times she attempted to become Miss Delaware, Kayla was bald. She wore a blond¹⁴ wig¹⁵ the last time she competed, winning the competition in 2010.

 

That win put her in position to take part in the Miss America Pageant in January.

 

Ms. Martell has used beauty pageants to help educate the public about alopecia. She compares wearing a hairpiece to other beauty queen traditions, like false eyelashes and hair weaves.

 

She says it is important for people to understand the emotional and social pressure that alopecia sufferers experience. She advises people with alopecia to contact a support group to tell them that they are not alone. She also says the most important form of beauty is inside out, not outside in.

 

Kayla Martell did not win the 2011 Miss America Pageant. But she was one of the top ten finalists. And her public comments have helped raised public understanding of alopecia.

 

Except for their hair loss, many people with alopecia are healthy individuals. And, since the hair follicles are not dead, some people with alopecia can experience periods of hair growth. Ms. Martell’s hair grew during the Miss America competition. She now has what is sometimes called a buzz¹⁶ cut, a short crop of soft, fuzzy hair. Alopecia patients may grow and lose their hair several times during their life.

 

Scientists are not exactly sure what causes alopecia areata. It is not clear why the body’s white blood cells begin to attack the cells in the hair follicles. There is no cure for the disease and no effective treatment that works for everyone.

 

Last year, researchers at Columbia University Medical Center in New York reported findings that they hope will help lead to a cure. The researchers found eight genes they believe may be important in causing the condition. They said many of the genes are also linked to autoimmune diseases. These include rheumatoid arthritis¹⁷, type 1 diabetes and celiac disease, a condition that affects the digestive system.

 

There are already effective treatments available for many of these conditions. Other treatments are being developed. The researchers say these treatments could prove to be promising¹⁸ for alopecia patients.

 

Angela Christiano is a professor at Columbia University Medical Center. She also suffers from alopecia areata. She says the study gives hope that there may someday be a cure for the condition.

 

The researchers studied 1,054 cases from the The National Alopecia Areata Registry. They looked for similarities in the genes that people with different levels of alopecia carry. They found that those with 13 to 14 similar genes had diseases that did not progress. Those with 16 or more similar genes usually progressed to alopecia universalis, or total baldness.

 

The researchers are now working on a genetic⁹ test to predict the severity of the disease. Professor Christiano says the next step is to repeat the study in future research, with a larger number of patients.

 

This SCIENCE IN THE NEWS was written by June Simms. Brianna Blake was our producer. I’m Barbara Klein. And, I’m Steve Ember. Join us again next week for more news about science in Special English on the Voice of America.

1 curly   

adj.卷曲的，卷缩的

参考例句：

• The little boy has curly hair.这小男孩长着一头卷发。
• She is tall and dark with curly hair.她高高的个子，黑皮肤，卷头发。

2 fetus   

n.胎，胎儿

参考例句：

• In the fetus,blood cells are formed in different sites at different ages.胎儿的血细胞在不同时期生成在不同的部位。
• No one knows why a fetus is not automatically rejected by the mother's immune system. 没有人知道为什么母亲的免疫系统不会自动排斥胎儿。

3 pregnancy   

n.怀孕，怀孕期

参考例句：

• Early pregnancy is often accompanied by nausea.怀孕早期常有恶心的现象。
• Smoking during pregnancy increases the risk of miscarriage.怀孕期吸烟会增加流产的危险。

4 shaft   

n.(工具的)柄，杆状物

参考例句：

• He was wounded by a shaft.他被箭击中受伤。
• This is the shaft of a steam engine.这是一个蒸汽机主轴。

5 overlooked   

v.忽视( overlook的过去式和过去分词 )；监督；俯视；（对不良现象等）不予理会

参考例句：

• He seems to have overlooked one important fact. 他好像忽略了一个重要的事实。
• This is a minor point, but it must not be overlooked. 此事虽小，然亦不可忽视。 来自《现代汉英综合大词典》

6 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

7 anemia   

n.贫血，贫血症

参考例句：

• The doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。
• I was put on iron tablets for my anemia.我曾因贫血吃补铁药片。

8 diabetes   

n.糖尿病

参考例句：

• In case of diabetes, physicians advise against the use of sugar.对于糖尿病患者，医生告诫他们不要吃糖。
• Diabetes is caused by a fault in the insulin production of the body.糖尿病是由体內胰岛素分泌失调引起的。

9 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

10 hormones   

n. 荷尔蒙，激素 名词hormone的复数形式

参考例句：

• This hormone interacts closely with other hormones in the body. 这种荷尔蒙与体內其他荷尔蒙紧密地相互作用。
• The adrenals produce a large per cent of a man's sex hormones. 肾上腺分泌人体的大部分性激素。

11 eyebrows   

眉毛( eyebrow的名词复数 )

参考例句：

• Eyebrows stop sweat from coming down into the eyes. 眉毛挡住汗水使其不能流进眼睛。
• His eyebrows project noticeably. 他的眉毛特别突出。

12 pageant   

n.壮观的游行；露天历史剧

参考例句：

• Our pageant represented scenes from history.我们的露天历史剧上演一幕幕的历史事件。
• The inauguration ceremony of the new President was a splendid pageant.新主席的就职典礼的开始是极其壮观的。

13 pageants   

n.盛装的游行( pageant的名词复数 )；穿古代服装的游行；再现历史场景的娱乐活动；盛会

参考例句：

• It is young people who favor holding Beauty pageants. 赞成举办选美的是年轻人。 来自互联网
• Others say that there's a fine line between the pageants and sexual exploitation. 其他人说，选美和性剥削之间只有非常细微的界线。 来自互联网

14 blond   

adj.金发的；n.白肤碧眼金发的人

参考例句：

• Her long blond hair spilled down over her shoulders.她那淡黄色的长发披垂在双肩。
• This blond man delivers newspaper every morning.这个白肤金发碧眼的男人每天早晨送报纸。

15 wig   

n.假发

参考例句：

• The actress wore a black wig over her blond hair.那个女演员戴一顶黑色假发罩住自己的金黄色头发。
• He disguised himself with a wig and false beard.他用假发和假胡须来乔装。

16 buzz   

v.充满了激动或活动的声音，发出低沉的声音

参考例句：

• My brain was in buzz.我的脑袋嗡嗡响。
• A buzz went through the crowded courtroom.拥挤的法庭里响起了一片乱哄哄的说话声。

17 arthritis   

n.关节炎

参考例句：

• Rheumatoid arthritis has also been linked with the virus.风湿性关节炎也与这种病毒有关。
• He spent three months in the hospital with acute rheumatic arthritis.他患急性风湿性关节炎，在医院住了三个月。

18 promising   

adj.有希望的，有前途的

参考例句：

• The results of the experiments are very promising.实验的结果充满了希望。
• We're trying to bring along one or two promising young swimmers.我们正设法培养出一两名有前途的年轻游泳选手。