阅读完形专练 - 学生版

阅读完形专练

一、阅读理解

A

How does your skin smell? Pretty well, as it turns out, thanks to receptors that can be found all over you. What’s more, they could help you heal.

There are more than 350 types of olfactory(嗅觉) receptors in the nose, noticing different scents. About 150 are also found in body issues such as those of the heart, liver and gut(胃)，but they are hard to study.

Hanns Hatt’s lab at Ruhr University Bochum in Germany focused on skin, which is easier to study, and tasted the response to scents(pleasant smells) of receptors in keratinocytes(角质化细胞)，the main skin cell type.

They found that an olfactory receptor in skin called OR2AT4 respond to man-made sandalwood(檀香) perfumes and skin care products. Rather than sending a message to the brain, as nose receptors do, the receptor caused cells to divide and migrate, important processes in repairing damaged skin.

Cell growth increased by 32 percent and cell migration by nearly half when keratinocytes in a test tube were mixed for five days with man-made sandalwood.

“There is a big trend towards olfactory receptors being found elsewhere in the body doing other jobs.” Says Joel Mainland o the Monell Chemical Senses Center in Philadelphia. So it is not unexpected to find receptors in skin, but it is a surprise to learn that they are involved in wound healing.

Hatt and Mainland both caution that these olfactory receptors are very finely adjusted, as is shown by their distinguishing between various man-made kinds of sandalwood. And there is genetic variability in human receptors, so your receptor might be a bit different from your neighbor’s.

It leaves open the question of whether receptors might differ so much between individuals that the man-made sandalwood that benefits one person might be useless or even poisonous to another

Hatt says the 150-200 olfactory receptors identified in tissue outside the nose represent a new family of targets for experiments and new opportunities to treat disease.

Treatments that heal wounds and repair the effects of ageing in the skin are likely to be the easiest to develop, he says. Understanding receptors on internal (inside your body) organs and creating beneficial drugs is likely to take longer.

( )1.What can we learn about OR2A T4?

A. It is a kind of nose keratinocyte.

B. It works like a nose receptor.

C. It can help damaged skin recover.

D. It can be found in man-made sandalwood.

( )2.How did the scientists observe olfactory receptor’s reactions to scents?

A. By studying receptors in body tissues

B. By comparing OR2A T4 and nose receptors.

C. By using man-made sandalwood in hospitals.

D. By mixing keratinocytes with man-made sandalwood.