首页
登录
职称英语
The would-be sleeper who refights his daily battles in bed——or rehearses to
The would-be sleeper who refights his daily battles in bed——or rehearses to
游客
2023-11-23
5
管理
问题
The would-be sleeper who refights his daily battles in bed——or rehearses tomorrow’s problems——finds it hard to fall asleep. Then he starts worrying about his inability to sleep, which increases his insomnia, which increases his worries, which... In a new development that may help the insomnia to break this vicious cycle, Dr. Werner P. Koella of the Worcester Foundation for the Experimental Biology has discovered a chemical in the brain that may control normal sleep.
The substance, known as serotonin, is one of a number of so-called neurohormones in the brain that researchers suspect play an important part in controlling the mind and the emotions. Such chemicals, researchers have learned, assist in transmitting nerve impulses from one nerve cell to another. Serotonin, Koella notes, is produced in particularly high concentrations in the hypothalamus, the "primitive" lower part of the brain and the brain stem, which joins the brain to the top of the spinal cord and is known to contain the centers controlling the level of transmitter substance in the brain stem and hypothalamus that regulate sleep.
In preliminary experiments, Koella found that giving serotonon to cats produced signs of sleep. Electrode leads were implanted in the cats’ brains and attached to an EEG (electroencephalogram) machine to record the brain waves; next, the serotonin was injected directly into the brain or an artery in the neck. The pupils of the animals’ eyes narrowed and the electroencephalograms showed slow waves characteristic of deep sleep within five to ten minutes.
More recently, Koella deprived cats of serotonin. The animals, again equipped with implanted electrodes, were given PCPA, a drug that blocks the formation of serotonin. They were then placed in small compartments fitted with one-way mirrors and watched round the clock.
Normally cats sleep about 15 hours a day; but Koella’s cats, after receiving PCPA, spent about 30 minutes of each day sleeping. Most of the time, their EEG’s showed the brainwave patterns of arousal. Occasionally the cats would curl up as if to go to sleep, but would soon get back on their feet to wander about. The animals showed signs of irritability and often meowed complainingly after a few days of sleep deprivation, but had normal reflexes. The effects of the PCPA wore off eight days to two weeks after administration of the drug; the cats returned to their normal sleeping patterns as serotonin levels in their brains rose again.
Koella believes that at least some types of chronic insomnia may be caused by a drop in brain - serotonin levels. The Worcester physiologist is now working on chemical ways to raise the brain’s serotonin levels and produce, in his words, "a truly physiological sleeping pill." Synthetic sleeping pills, such as barbiturates, bring sleep, but at a price: they depress the central nervous system, reduce heart action and respiration——and they can become habit-forming or even addictive.
In one promising experiment toward the goal of letting the body "make its own pill," Koella has found that administration of 5-hydroxytryptophan, the chemical substance from which the body derives serotonin, will quickly restore a normal sleeping pattern to cats lacking in serotonin. [br] The language used in this article indicates that Dr. Koella _______.
选项
A、is positive that serotonin controls sleep
B、is quite uncertain whether serotonin controls sleep
C、thinks that serotonin can’t be extracted
D、thinks that serotonin might control sleep
答案
D
解析
A项说Dr.koella很确定serotonin能控制睡眠,这一点文中已表明是不肯定的;但B项说他十分不确定,也不能这么说;而C项说serotonin不能被提取,实验证明是可以提取的;所以应选D项,Dr.koella认为serotonin可能可以控制睡眠。
转载请注明原文地址:https://tihaiku.com/zcyy/3211187.html
相关试题推荐
InChina,groomstypicallyhavetopaytheirwould-bewivesa"bridepri
Thewould-besleeperwhorefightshisdailybattlesinbed——orrehearsesto
Thewould-besleeperwhorefightshisdailybattlesinbed——orrehearsesto
Thewould-besleeperwhorefightshisdailybattlesinbed——orrehearsesto
Thewould-besleeperwhorefightshisdailybattlesinbed——orrehearsesto
随机试题
ItIsn’tEasyBeingGreenGreenstoriesofhotelsA)Overthesum
如果只看到实践标准的确定性、绝对性,否认实践标准的不确定性、相对性,就会导致()
麻醉药品只限用于:()A.癌症止痛的需要 B.临床手术的需要 C.医
生殖器结核最先侵犯的部位是A.卵巢,其次是输卵管 B.子宫内膜,其次是输卵管
在讲解完“生物大分子以碳链为骨架”后,教师提问:“如何理解‘碳是生命的核心元素“
把迁移分为正迁移与负迁移,其分类依据是【】A:迁移的结果 B:迁移的情景
慢性根尖周炎的最重要的临床表现是A.深龋洞已穿髓 B.X线片根尖周透射区 C
氟牙症的牙着色改变是由于A.牙齿发育过程中氟与釉质结合 B.釉质基质遇光发生化
《环境影响评价技术导则—大气环境》推荐的进一步预测模型不包括( )。A.ADM
根据《全国生态环境保护纲要》,对生态功能保护区采取的保护措施包括()。A、停止一
最新回复
(
0
)