问题 问答题 简答题

什么是尸僵?简述尸僵形成的原因及过程。

答案

参考答案:刚刚宰后的肌肉,各种生物细胞内的生物化学反应仍在继续进行但是由于放血带来了体液平衡的破坏、供氧的停止,整个细胞内很快变成无氧状态,从而使葡萄糖和肌糖原的有氧分解变成无氧酵解,在有氧条件下一分子的葡萄糖可以产生39个ATP分子,而在无氧条件下只能产生3个ATP,从而ATP的供应受阻,肌肉内ATP的含量迅速下降和乳酸浓度的提高,肌浆网钙泵的功能丧失,是肌浆网中的Ca2+逐渐释放而得不到回收,钙离子浓度升高,引起肌动蛋白沿着肌球蛋白滑动收缩,另一方面引起肌球蛋白头部的ATP酶活化,加快ATP浓度加速下降,同时由于ATP的丧失又促使肌动蛋白与肌球蛋白之间的结合形成不可逆的肌动球蛋白,从而引起肌肉连续且不可逆的收缩,收缩达到最大程度时即形成了肌肉的宰后僵直,也称尸僵。

氧气供应停止---细胞内生物化学反应继续进行---形成ATP少,肌肉内ATP浓度迅速下降---加上乳酸浓度提高---肌浆网钙泵丧失功能---释放大量钙离子,而得不到回收---引起肌动蛋白沿着肌球蛋白滑动收缩---并活化肌球蛋白头部的ATP酶---ATP丧失---形成不可逆的肌动球蛋白---引起连续不可逆收缩---尸僵。

阅读理解

Over the last 25 years, British society has changed a great deal – or at least many parts of it have.   小题1:. Ideas about social class – whether a person is “working - class” or “middle - class” – are one area in which changes have been extremely slow.

  In the past, the working-class tended to be paid less than middle-class people. The typical working man would collect his wages on Friday evening and then, it was widely believed, having given his wife her "housekeeping", would go out and squander the rest on beer and betting.

  The old style of what a middle-class man did with his money was perhaps nearer the truth. He was-and still is - inclined to take a longer-term view. Not only did he regard buying a house as a most important thing, but he also considered the education of his children as extremely important. 小题2:. Only in very few cases did workers have the opportunity (or the education and training) to make such long-term plans.

  小题3:In a large number of cases factory workers earn as much as their middle – class supervisors (管理者). Social security and laws to improve century, have made it less necessary than before to worry about "tomorrow". Working-class people seem slowly to be losing the feeling of inferiority(自卑感). In fact there has been a growing tendency in the past few years for the middle-classes to feel slightly ashamed of their position.

小题4:.They generally tend to share very similar tastes in music and clothes, they spend their money in having a good time, and save for holidays or longer-term plans when necessary. There seems to be much less difference than in precious generations.小题5:. As long as this gap exists, there will always be a possibility that new conflicts and jealousies will emerge, or rather that the old conflicts will re-appear, but between different groups.

A.Nowadays, a great deal has changed

B.Both of these provided him and his family with security

C.As a result, differences in life – styles and attitudes came into existence

D.However, we still have a wide gap between the well – paid and the low - paidE.In recent years, the working – class people have begun to design long – term plans

F.In some ways, however, very little has changed, particularly where attitudes are concerned

G.The changes in both life – styles and attitudes are probably most easily seen amongst younger people

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