什麼是膽固醇
存在血漿和所有動物組織內的一種蠟狀物質。是一種類固醇,分子式為C2746。膽固醇為生命所必需,它是細胞膜的重要組成,為體內合成膽酸、類固醇激素和維他命D的原料或中間產物。膽固醇並不溶於血,故須附於某些蛋白質複合體(稱為脂蛋白)上,方能於血液中運輸。它是由肝臟和其他一些器官制造,以飲食攝取量的多寡來調節。血中膽固醇過高會沈積在血管內壁上(參閲arteriosclerosis),導致冠狀動脈心臟病。1985年布朗(M. Brown, 1941~)和戈德斯坦(Joseph Goldstein, 1940~)因發現這個過程而共獲諾貝爾醫學或生理學獎。避免血膽固醇過高的最佳對策為降低飲食中的膽固醇攝取量以及減少動物性脂肪(如飽和或過飽和脂肪)的攝取量。參閲triglyceride。
cholesterol
Waxy organic compound found in blood and all animal tissues. It is a steroid, with molecular formula C27H46O, containing four rings in its structure. Cholesterol is essential to life; it is a primary component of cell membranes and a starting or intermediate material from which the body makes bile acids, other steroid hormones, and vitamin D. It is made in the liver and some other organs, in greater or lesser amounts depending on the amount recently consumed in the diet. It circulates in the blood in compounds called lipoproteins, since it is not water-soluble alone. Excess cholesterol in the blood forms deposits in arteries (see arteriosclerosis), which can lead to coronary heart disease. Michael Brown (born 1941) and Joseph Goldstein (born 1940) won a Nobel Prize in 1985 for their work in discovering this process. Since the body makes cholesterol from fats, blood cholesterol cannot be reduced by limiting only the amount of cholesterol in the diet; the amount of fat, especially saturated fat (see saturation, fatty acid) must also be reduced. See also triglyceride.
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什麼是新生兒
從娩出開始至出生後28天的嬰兒。這個時期稱為新生兒期。約90%以上的新生兒為正常新生兒,其他為低出生體重兒、早產兒、小於胎齡兒、過期產兒以及巨大兒等。正常新生兒通常指孕37~42周娩出的體重在2500~4000g之間,各器官發育相對成熟的足月兒。新生兒期的特點是嬰兒...
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什麼是熟地黃
常用補血藥。別名熟地。始載於《本草圖經》。為玄蔘科多年生草本植物地黃Rehmanniaglutinosa根經加黃酒拌蒸至內外色黑而油潤,或直接蒸至黑潤而成(圖1)。因其色黃,質量下沉,蒸熟曬乾入藥,故名。產地和性狀中國大部地區均有生產,主產於河南孟縣、温縣、武陟、博愛等...
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什麼是合成抗菌藥
用化學合成方法制成的抗菌藥物。主要包括磺胺類(見磺胺類藥)、喹諾酮類、呋喃類等。喹諾酮類有別於磺胺和抗生素的一類抗菌藥物,其化學結構中均有4-吡啶酮-3羧酸(見圖)。這類藥物的特點是:抗菌活性強;細菌對這類藥物和其他類抗生素之間無交叉耐藥性;對質粒介導的耐藥...
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什麼是殺蟲藥中毒
殺蟲藥進入人體引起的中毒。殺蟲藥是來自植物或人工合成用以殺滅農業害蟲和衞生害蟲的有機化合物。因為殺蟲藥對農業增產的效果十分顯著,對控制多種傳播傳染病的媒介昆蟲又非常有效,已成為城鄉人民生產和生活的心需品。除劇毒殺蟲藥能引起人、畜中毒外,一些低毒殺...