首页
登录
职称英语
Importance of Vitamins Vitamins, which come in man
Importance of Vitamins Vitamins, which come in man
游客
2024-01-05
6
管理
问题
Importance of Vitamins
Vitamins, which come in many different types all of which are quite diverse in chemical configuration and function, can be any of several organic substances that are separated into water-soluble and fat-soluble groups. Originally defined as organic compounds obtainable in a normal diet and capable of maintaining life and promoting growth, vitamins are differrent from carbohydrates, fats, and proteins in function, as well as in the quantities in which organisms require them. So critical are vitamins to a body’s essential strength and health that if they are absent from the diet or not properly absorbed by an organism, a specific deficiency disease may develop.
The term vitamin originated from "vitamine," a word first used in the early 19th century to designate a group of compounds considered vital for life (though the term "accessory food factor" sometimes is used interchangeably to refer to these substances). Like other nutrients, vitamin consumption is imperative to keep our bodies functioning properly, and if there is a lack of vitamin consumption, the body will fail to react in a way that’s considered healthy. Lack of vitamin A will result in various disorders that most commonly involve the eye and the tissues around it. One of the earliest symptoms of vitamin A deficiency is nyctalopia, the medical term for night blindness, which causes a visual failure to adapt quickly from light to darkness and an inability to see in the dark. This aspect of vision is normally dependent on rhodopsin, a protein found in the eye that maintains itself only in the presence of vitamin A; in the lack of vitamin A, rhodopsin will malfunction.
These earlier symptoms are quite harmless but the side effects can become increasingly serious if not treated early on. If the deficiency is severe and persists, especially in malnourished infants and children, a condition known as xerophthalmia--when the eyes are sensitive to light, the secretion of lubricating tears is stopped, and the eyelids become swollen and develop pus -- may develop. Furthermore, the mucous surfaces of the eye may become eroded, allowing infection to set in, thus leading to ulceration and other destructive changes of the cornea and other structures of the eye, resulting eventually in blindness.
A Early signs of vitamin A deficiency may also be reflected in changes in the membranes of the mouth, throat, and respiratory and genito-urinary passages where the lining membranes become malnourished and dry and lose their cilia, the tiny hairlike projections that normally help in clearing away foreign particles. B The natural immune system is weakened and if insufficient intake of vitamin A is prolonged, the skin may become dry and rough. C Vitamin A deficiency may also result in defective bone and teeth formation and in poor general growth.D
However, an excessive intake of vitamin A can also cause severe damages to the body causing a symptom called "hypervitaminosis A", which happens when a person takes in more than 150 milligrams of vitamin A over a long period of time; the vitamins are stored in the liver and can reach dangerous level because the A vitamins are not employed to make the bodies stronger, but rather, stored as toxic material. Excessive amounts of vitamin A can cause nausea, dryness of skin, blurred vision, drowsiness, and bone pain.
Vitamin A can be found in all animal livers, in milk products, and in many yellow and green leafy vegetables which contain carotenes, chemically related substances that are converted to vitamin A in the body. There are various other vitamins that the human body needs in order to survive; the excessive intake of vitamin A, or the lack of intake of other vitamins, causes detriment to the human body--at all times, moderation is key. [br] The word malnourished in the passage is closest in meaning to
选项
A、emaciated.
B、melancholy.
C、ill.
D、hungry.
答案
A
解析
转载请注明原文地址:https://www.tihaiku.com/zcyy/3334486.html
相关试题推荐
Atthestartofthetutorial,thetutoremphasisestheimportanceof[br][orig
Atthestartofthetutorial,thetutoremphasisestheimportanceof[br]【25】[
Atthestartofthetutorial,thetutoremphasisestheimportanceof[br]Anexa
Atthestartofthetutorial,thetutoremphasisestheimportanceof[br][orig
Atthestartofthetutorial,thetutoremphasisestheimportanceof[br][orig
Atthestartofthetutorial,thetutoremphasisestheimportanceof[originalte
(Whencannedusing)propermethods,foodsuffers(no)lossillvitaminsor(ano
ImportanceofVitaminsVitamins,whichcomeinman
ImportanceofVitaminsVitamins,whichcomeinman
ImportanceofVitaminsVitamins,whichcomeinman
随机试题
TheChurchofEnglandwasestablishedinA、1532.B、1534.C、1453.D、1531.B英格兰国教成立
Naturallanguageinterfacesenabletheusertocommunicatewiththecomputer
在教学中讲授“果实”概念时,既选可食的果实,又选不可食的果实(如棉子等),这样才
发行企业债券,需要()批准。A:中国证监会B:中国人民银行C:中国银监会D
假设大豆期货1月份、5月份、9月份合约价格为正向市场。某套利者认为1月份合约与5
能补虚的药物是A.小蓟 B.槐花 C.炮姜 D.仙鹤草 E.艾叶
下列关于税款追征权的表述,正确的是()。A.因扣缴义务人计算错误等失误,未缴或
下列关于进口货物关税完税价格的说法正确的是( )。A.运往境外修理的货物以海关
(2019年真题)快餐业由很多中小餐饮企业组成,其中没有任何一个企业占有显著的市
根据《建设项目工程总承包管理规范》GB/T50358-2017,工程总承包项目管
最新回复
(
0
)