首页
登录
职称英语
The sensation of pain cannot accurately be described as "located" at the poi
The sensation of pain cannot accurately be described as "located" at the poi
游客
2024-01-13
54
管理
问题
The sensation of pain cannot accurately be described as "located" at the point of an injury, or, for that matter, in any one place in the nerves or brain. Rather, pain signals—and pain relief—are delivered through a highly complex interacting circuitry.
When a cell is injured, a rush of prostaglandin’ s sensitizes nerve endings at the injury. Prostaglandins are chemicals produced in and released from virtually all mammalian cells when they are injured: these are the only pain signals that do not originate in the nervous sys- tern. Aspirin and other similar drugs(such as indomethacin and ibuprofen)keep prostaglandins from being made by interfering with an enzyme known as prostaglandin synthetase, or cyclooxy- genase. The drugs’ effectiveness against pain is proportional to their success in blocking this enzyme at the site of injury.
From nerve endings at the injury, pain signals move to nerves feeding into the spinal cord. The long, tubular membranes of nerve cells carry electrical impulses. When electrical impulses get to the spinal cord, a pain-signaling chemical known as substance P is released there. Substance P then excites nearby neurons to send impulses to the brain. Local anesthetics such as novo-caine and xylocaine work by blocking the electrical transmission along nerves in a particular area. They inhibit the flow of sodium ions through the membranes, making the nerves electrically quiescent; thus no pain signals are sent to the spinal cord or to the brain.
Recent discoveries in the study of pain have involved the brain itself—the supervising organ that notices pain signals and that sends messages down to the spinal cord to regulate incoming pain traffic. Endorphins-—the brain ’ s own morphine—are a class of small peptides that help to block pain signals within the brain itself. The presence of endor- phins may also help to explain differences in response to pain signals, since individuals seem to differ in their ability to produce endorphins. It now appears that a number of techniques for blocking chronic pain—such as acupuncture and electrical stimulation of the central brain stem—involve the release of endorphins in the brain and spinal cord. [br] It can be inferred from the passage that if the prostaglandin synthetase is only partially blocked, which of the following is likely to be true?
选项
A、Some endorphins will be produced, and some pain signals will be intensified.
B、Some substance P is likely to be produced , so some pain signals will reach the brain.
C、Some sodium ions will be blocked, so some pain signals will not reach the brain.
D、Some prostaglandins will be produced, but production of substance P will be prevented.
E、Some peptides in the brain will receive pain signals and begin to regulate incoming pain traffic.
答案
B
解析
如果前列腺素合成只是部分受阻,下面哪个将会发生?前列腺素只部分受阻,意味着痛信号将向脊髓传播。∴B正确。一些P物质会产生,一些痛信号将抵达脑神经L28—31,这正是原文第三段内容。A.“endorphins”是否产生和痛信号如何并没有直接联系。C.一些钠离子被阻碍。这是使用局麻药的后果,和痛信号无直接联系。D.P物质制造将被阻止。说反了。E.peptides接收痛信号并调节痛传输。文中无。
转载请注明原文地址:http://tihaiku.com/zcyy/3357520.html
相关试题推荐
Notalways______theywantto.A、peoplecandowhatB、peoplecannotdowhatC、can
Notalways___________theywantto.A、peoplecandowhatB、peoplecannotdowhatC
________,Icannotspareanytimetoreadit.A、HoweveramusingthestoryisB、Ho
36Ifxisanintegerandy=4x+3,whichofthefollowingcannotbeadivisorof
Ifnisallpositiveinteger,thentheunitsdigitofn102cannotbewhichofth
Whichofthefollowingmostaccuratelystatesthemainideaofthepassage?[br]
Whichofthefollowingmostaccuratelystatesthemainideaofthepassage?[br]
Whichofthefollowingmostaccuratelystatesthemainideaofthepassage?[br]
Whichofthefollowingmostaccuratelystatesthepurposeofthepassage?[br]I
Whichofthefollowingmostaccuratelystatesthepurposeofthepassage?[br]I
随机试题
Researchersinvestigatingbrainsizeandmentalabilitysaytheirworkoffer
Ifresearcherscandetermineexactlywhatiswrongwithpeoplewhosufferfromt
ThethemeofThanksgivinghasalwaysbeenA、friendshipandhappiness.B、peaceand
岁月悠悠,沧桑巨变。历史是最生动的教材。法西斯发动的侵略战争给人类带来了浩劫,也教育了世界人民。世界人民赢得了战争的胜利,赢得了和平与进步。半个世纪过去
商品的本质属性是()。A.使用价值 B.价值 C.交换价值
有下列情形之一的设备,需提前或尽快安排停电试验。(A)带电检测显示设备状态不良
简述现代企业人力资源管理各个历史发展阶段的特点。
总需求是指一国在一定时期内,社会对最终产品和劳务愿意购买并有支付能力的总需求量,
某工程,实施过程中发生如下事件: 事件1.总监理工程师对项目监理机构的
8个月男孩,发热、咳嗽4天,加重伴气促2天,精神不振,食欲减退。查体:体温37.
最新回复
(
0
)