2013年职称英语卫生类概括大意题模拟（23）4 @8 e. U" k+ j$ \2 O! W
Quit Smoking 4 \2 ?) U) U/ p" _ p# y: v
1 Anyone who has ever tried to give up smoking cigarettes knows the meaning of being hooked. Even those who succeed in quitting for the first time suffer the same 75% relapse rate as recovering alcoholics and heroin addicts. Last week, the U. S. Surgeon General made official what everyone has recognized for a long time-tobacco, like cocaine or heroin, is addictive.
& x- E: t" U K4 C$ y: i 2 The panic of a heave smoker bereft of cigarettes speaks alarmingly of a physiological force at work that is more powerful than mere desire. Not long after taking up the habit, smokers become tolerant of nicotine's effects as with heroin and cocaine, dependence quickly follows. 考试用书
4 F1 b- X* ~' r9 X4 n* X* k 3 Like many drugs that affect the nervous system, nicotine at once stimulates and relaxes the body. Because it is inhaled, it takes only seven to ten seconds to reach the brain — twice as fast as intravenous drugs and three times faster than alcohol. Once there, it mimics some of the actions of adrenaline, a hormone, and acetylcholine, a powerful neurotransmitter that touches off the brain’s alarm system, among other things. After a few puffs, the level of nicotine in the blood skyrockets, the heart beats faster and blood pressure increases. The result is that smokers become more alert and may actually even think faster. + s8 q! K* L) t
4 Nicotine operates on other parts of the body as well. By constricting blood vessels, it casts a pallor over the face and diminishes circulation in the extremities, often causing chilliness in the arms and legs. It relaxes the muscles and suppresses the appetite for carbohydrates. Since nicotine cannot be stored in the body, smokers maintain a relatively constant level in the blood by continuing to smoke. * c1 N9 c; E; M9 s Y
9 J, t1 `* h2 Q5 d/ t) L 5 As for nicotine's addictive qualities, the Surgeon General cited several national surveys that reveal 75% to 85% of the nation's 51 million smokers would like to quit but have so far been unable to do so. |
发表于 2012-8-15 23:30:26
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