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  二套周日19:00首播 一套周五15:10 十套12:00、19:00重播

Nicotine:the desirable drug    
  Pure Nicotine,just three drops can kill an adult. Yet every day, millions of people take it into their lungs.

  These are tobacco plants, the only natural source of nicotine. We now understand that it's this substance that keeps people smoking, despite all the warnings. It one of the most addictive drugs we know.

  As tobacco cigarette burns, a potpourri of 4000 chemicals is released, including carbon monoxide and hydrocyanic acid. It's there, rather than nicotine that is responsible for the major health problems like lung cancer, heart disease, and mphysema. But the thing that gets you hooked on the whole vaporous cocktail is nicotine.

  While inhaling deeply, you also get more of the carbon monoxide and tars that cause lung and heart disease. So the cigarettes you've bought to lessen the impact on your health may actually be worse for you.

  While the pharmaceutical industry gears up to exploit nicotine's positive side, others are uncovering the havoc the drug can cause, especially in the very young.

  Pregnant women are warned not to smoke. It lowers the baby's birth weight. We've known for some tome that carbon monoxide in tobacco is the culprit here.

  But new research is showing that nicotine adds further, more insidious risks.

  Here's a mom who smoked during pregnancy. Her baby has a baby of normal weight. Do we need to be concerned about that baby or is weight the whole story? And it turns out that weight is not the whole story. In fact, it's very misleading indicator, more so with nicotine than with virtually any other kind of damaging event during gestation.

  The damage happens as the brain is developing. And nicotine again replaces acetylcholine at a critical moment. And nicotine again replaces acetylcholine at a critical moment.

  Building a brain is all about making the right connections. In particular it hinges on the way things called axon form a nerve network.

  First young nerve cells move towards their allotted sites in the brain. Once there, they'll receive a signal, a burst of acetylcholine. That activates the next stage. Each nerve cell sends out an axon, a long fiber, to make contact with a target cell and build connections. If nicotine is introduced, the cells get confused and activate the process too soon.

  It's done it at the wrong time. It's done it before you've got the right number of cells. Plus, it's now sending out its offshoot, its axon, to find its target cell, but the target cell may not even have migrated into the right lace yet. So the axon gets lost and winds up innervating the wrong cells. So it's like you have a radio with the wires going to the wrong places, and naturally, that causes functional disruption.

  We've now got a good idea, which regions of the brain are prone to this faulty wiring. One is the respiratory center and may explain a known link between smoking and Sudden Infant Death Syndrome.

  It turns out that u can account for probably over half of Sudden Infant Death from tobacco use. In fact, a very carefully controlled study done in Sweden attributed 70 percent of Sudden Infant Death to tobacco smoking. And that's the number one killer of infants under one year of age.

  What triggers Sudden Infant Death is a period of asphyxia during sleep, when the baby slows or stops breathing.

  Normally the brain's respiration center will detect the plummeting wxyen levels and make baby breathe deeper. At the same time, a rush of adrenalin makes the heart beat faster.

  But in nicotine babies, both these survival systems may be incorrectly wired and the baby simply suffocates.

  To those watching this program who think that quitting has nothing to do with them, just remember, the ads are right when they say cigarettes help a smoker cope with stress. We need to think carefully about what happens when someone quits. Lives may depend on it - and not just the smoker's.


尼古丁

  三滴纯净的尼古丁就可以毒死一个成年人。但每天仍有数以百万的人将它吸入肺中。

  这些是烟叶,提炼尼古丁的惟一自然资源。正是尼古丁让人不顾警告,吸烟成瘾。它是最容易上瘾的毒品之一。

  当烟被点燃时,融合了四千种化学品的气体被释放出来,其中包括一氧化碳和氢氰酸。其实他们比尼古丁更厉害,是造成肺癌、心脏病和肺气肿的主要原因。但是让你沉迷于这种“气体鸡尾酒”的是尼古丁。

  深呼吸时,烟草里的一氧化碳和焦油能够引发肺病和心脏病。所以用以减缓压力的烟草反而对健康更加不利。

  当药学界不断研究出尼古丁的正面作用时,这种毒品引发的各种灾难也被证实,它作用在年幼的人身上更加明显。

  怀孕妇女被告诫不能吸烟,否则新生婴儿的体重会降低。一些书中说,烟里的一氧化碳是罪魁祸首。

  但新的实验表明,尼古丁会使危险变本加厉。

  这里有一个在怀孕期吸烟的母亲。她的孩子体重正常。但我们是该关心他的体重呢还是他的整体情况?其实体重不能代表所有问题,那是一个误区。尼古丁带来的危害要大于怀孕期其它的伤害。

  损害是在大脑发育时出现的。尼古丁在关键时候替代了乙酰胆碱。建造大脑就是组建正确的连接网络。所有单独连接信息的神经轴突形成了一个神经网。

  最初的神经细胞向大脑中指定的地点移动。到达后,他们将接收一束乙酰胆碱组成的信号,以此为下一步做准备。每个神经细胞放出一条神经轴突,用来和目标细胞进行连接。而尼古丁的介入,使细胞活动紊乱,导致程序运行速度过快。

  但程序完成的不是时候,它在你获取到正确的细胞数量之前就结束了。现在它开始发射神经轴突去寻找目标细胞。而目标细胞尚未运动到位,于是神经轴突无法连接,并终止了错误细胞的神经控制活动,这就像收音机的电线插错了地方,自然会引起故障。

  我们知道了大脑的区域就像这个接错的配线。其中的呼吸中枢也许能解释吸烟和婴儿猝死综合症之间的关联。

  现在你能了解到大约一多半的婴儿猝死是烟草造成的。瑞典的一项缜密受控研究表明,有70%的婴儿猝死是吸烟导致的。这也是一岁以下婴儿夭折的最大死因。

  睡眠中,当宝贝的呼吸放慢或停止时,窒息引发了婴儿死亡。

  通常,大脑的呼吸中枢探测到氧气水平的下降时,会加深婴儿的呼吸。体内同时分泌出一股肾上腺素让心跳加快。

  但对于受到尼古丁影响的孩子,由于两种生存系统的信息不能正确传输,他们很容易会发生窒息。

  对于那些沉迷于抽烟的人而言,烟可能让人感到压力减轻。但我们也要想到戒烟后所发生的变化。大家的生命也许依赖于此,这并不仅仅指那些吸烟者。





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