首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
The would-be sleeper who refights his daily battles in bed——or rehearses tomorrow’s problems——finds it hard to fall asleep. Then
The would-be sleeper who refights his daily battles in bed——or rehearses tomorrow’s problems——finds it hard to fall asleep. Then
admin
2009-02-10
58
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.
The information in paragraph 5 indicates that PCPA was responsible for _______.
选项
A、a lack of sleep
B、the cats’ meowing
C、normal sleeping patterns
D、sleeping about 15 hours a day
答案
A
解析
第五段中关于PCPA的有关描述为“Normally cats sleep about 15 hours a day;but koella’s cats,after receiving PCPA,spent about 30 minutes of each day sleeping.”即注射了PCPA后,猫每天只睡 30分钟了,相对于以前要睡15小时,少了很多,所以A项正确。
转载请注明原文地址:https://kaotiyun.com/show/bL6K777K
0
专业英语四级
相关试题推荐
HaveyouevernoticedacertainsimilarityinpublicparksandbackgardensinthecitiesoftheWest?Aubiquitouswoodlandmix
A、Threedays.B、Twodays.C、Fourdays.D、Oneday.C信息题。Paul表示:Putdownafewdaysonthebeach.Ican’tcomebackwithoutasunta
Intoday’scompetitiveworldwhenparentsarebusyaccomplishingtheircareergoals,moreandmorechildrenarebeingbroughtup
A、Poverty.B、Parents’neglect.C、Healthproblems.D、Socialreasons.A
Inrecentyears,TVtalentshowshaveburstontoourscreenswithavengeance.Withmostshowingordinarymembersofthepublic
(1)TheChildrenAct1989doesnotassuchrequireparentsorpersonsholdingparentalresponsibilitytoeitherinvolvechildren
(1)TheChildrenAct1989doesnotassuchrequireparentsorpersonsholdingparentalresponsibilitytoeitherinvolvechildren
(1)Thishasbeenquiteaweekforliterarycoups.Inanalmostentirelyunexpectedmove,theSwedishAcademyhavethislunchtim
______,Imustdoanotherexperiment.
随机试题
具有趋化作用的物质有
具有控制腠理开合、汗液排泄之气是
癫痫小发作首选药物是()
下述哪一点关于利尿药作用部位的描述是错误的
胰岛素注射部位是
如果被审计单位是上市实体,注册会计师在就其独立性与被审计单位的治理层进行沟通时,下列通常不属于沟通内容的是()。
阅读材料,回答121~125题。 8月份,规模以上工业原煤生产增速回升,煤炭进口保持较高水平:原油生产增速由负转正,进口继续增加;天然气生产保持较快增长,进口持续高速增长;电力生产加快。 一、原煤生产增速回升,煤炭进口保持较高水平,市场价格小幅波动
法律对同一事项的新的一般规定与旧的特别规定不一致,不能确定如何适用时,由()裁决。
Veryfewscientists______withcompletelynewanswerstotheworld’sproblems.
InJapan,wherecareeropportunitiesforwomenarefew,wheredivorcecanmeanalifeofhardship,andwheremostfemalenamesa
最新回复
(
0
)