问题 选择题

如图为人体上肢骨骼肌的模式图,当我们双手处于自然下垂时,①②肌肉的状态是(   )

A.①收缩②舒张

B.①舒张②收缩

C.①②同时收缩

D.①②同时舒张

答案

答案:D

题目分析:图中①肱二头肌,②肱三头肌,骨骼肌受神经刺激后有收缩的特性,同一块骨骼肌的两端跨过关节分别固定在两块不同的骨上,骨骼肌有受刺激收缩的特性,骨骼肌只能收缩牵拉骨而不能将骨推开,因此一个动作的完成总是由两组肌肉相互配合活动,共同完成的,双手自然下垂时,肱二头肌和肱三头肌都处于舒张状态,因此,感觉比较轻松。

点评:此题是一道基础知识题,解答此类题目的关键是理解人体完成一个运动都要有神经系统的调节,有骨、骨骼肌、关节的共同参与,多组肌肉的协调作用,才能完成。

阅读理解

Vans, Keds, Dollies—they sound like the names of rock bands, but if you have teenagers, you'll know they're actually the latest in teenage footwear.

But experts are now warning that the latest shoes in different styles will be causing teenagers discomfort(不舒适) in the short term and storing up years of foot, knee and back pain in the future.

Here, the experts discover the problems caused by teenagers' shoe choice.

KEDS/VANS

Slip-on shoes with elastic (弹性的) sides are particularly popular among teenage boys - with Keds and Vans the most sought-after brands.

The main problem is that they are just too flat—so flat that the heel, which hits the ground first, also becomes damaged and painful.

BALLET PUMPS

The worst shoes of all are such light and thin dolly shoes. The problem is partly their flatness, as with Keds and Vans. However ballet pumps, which have no string or heel, have other specific problems.

“As the shoe has no fastening device, it relies on the toes to keep the shoe on, causing a difficult gait(步法), this leads to short- and long-term problems such as calluses(茧子), heel and knee pain.”

WEDGES AND STILETTOS

These shoes can also cause problems with gait. They may look good, but the heels on these are so high they can force the wearer's body weight forward, making them very shaky.

Teens who wear these shoes regularly are also in danger of joining those millions of women with continuous back pain.

SCHOOL SHOES

So what do podiatrists(足科医生)have on their wish list, especially for everyday wear?

Something in a natural, breathable fabric, with a string to hold it on, with a small heel and a deep toe-box that does not press the toes, such as Clark's, Marks & Spencer or Rhino.

If your teen insists on wearing 'bad' shoes, get them some simple foot orthotics(矫形器) in the shoes. These support and correct the movement of the foot and, properly fitted by a podiatrist, can often change their walk and halt the damage.

小题1:Of all the shoes mentioned(提到) in the passage, which can cause the worst problems?

A.Marks & Spencer.

B.Wedges & Stilettos.

C.Keds and Vans.

D.Ballet Pumps.小题2:Which pair of shoes may not be found on the podiatrists’ wish list?

A.

B.

C.

D.小题3:The underlined word “halt” in the last paragraph probably means _______.

A.increase

B.worsen

C.stop

D.cause小题4:In which column of Mail Online can you find this passage?

A.Sports.

B.Science.

C.Health.

D.Shopping.

名词解释