caffeine


caffeine
caffeinic /ka fee"nik, kaf'ee in"ik/, adj.
/ka feen", kaf"een, kaf"ee in/, n. Chem., Pharm.
a white, crystalline, bitter alkaloid, C8H10N4O2, usually derived from coffee or tea: used in medicine chiefly as a nervous system stimulant.
Also, caffein.
[1820-30; < F caféine, equiv. to café COFFEE + -ine -INE2]

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Heterocyclic compound that, like other alkaloids, has marked physiological effects.

It occurs in coffee beans, tea leaves, kola nuts, cacao, maté, and guarana and in the products made from them. Its stimulating effect on the central nervous system, heart, cardiovascular system, and kidneys makes it medically useful in treating respiratory depression caused by overdose of barbiturates, morphine, or heroin. Its positive effects can include improved motor performance, decreased fatigue, increased alertness, and enhanced sensory activity. Excessive caffeine can produce irritability, anxiety, insomnia, and potentially serious symptoms such as heart irregularities and delirium. Much of the caffeine included in many over-the-counter stimulants, cold remedies, and painkillers has been extracted during production of decaffeinated coffee and tea.

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      nitrogenous organic compound of the alkaloid group, substances that have marked physiological effects. Caffeine occurs in tea, coffee, guarana, maté, kola nuts, and cacao.

      Pure caffeine (trimethylxanthine) occurs as a white powder or as silky needles, which melt at 238° C (460° F); it sublimes at 178° C (352° F) at atmospheric pressure. It is very soluble in hot water; upon cooling, the solution deposits crystals of caffeine monohydrate. Caffeine is generally less soluble in organic solvents than in hot water. It is odourless but has a bitter taste.

      Caffeine is present in ground coffee in amounts ranging between 0.75 and 1.5 percent by weight. The average cup of coffee thus contains about 100 mg (0.003 ounce) of caffeine. The caffeine content of tea varies greatly depending on the strength of the tea, but it averages about 40 mg. There are also about 40 mg (0.0014 ounce) of caffeine in a 12-ounce glass of carbonated cola beverage.

      Caffeine has a stimulating effect on the central nervous system (nervous system, human), heart, blood vessels, and kidneys. It also acts as a mild diuretic. Caffeine's potent stimulatory action makes it a valuable antidote to respiratory depression induced by drug overdose (e.g., from morphine or barbiturates). The positive effects that have been described in people who use caffeine include improved motor performance, decreased fatigue, enhanced sensory activity, and increased alertness. These positive effects may partly explain the compulsion of many adults to consume coffee or other caffeine-containing beverages as part of the morning ritual of awakening. However, caffeine intake may also produce in people such negative effects as irritability, nervousness or anxiety, jitteriness, headaches, and insomnia. By the mid-1980s decaffeinated coffee and soft drinks had become widely available, giving consumers the choice of regulating their caffeine intake while continuing to enjoy these beverages.

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Universalium. 2010.

Look at other dictionaries:

  • Caffeine — Caffeine …   Deutsch Wikipedia

  • caffeine — caffeine. См. кофеин. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • caffeine — trimethyl derivative of xanthine, 1830, from Ger. Kaffein, coined by chemist F.F. Runge (1795 1867), apparently from Ger. Kaffee coffee (see COFFEE (Cf. coffee)) + chemical suffix INE (Cf. ine) (2) (Ger. in). The form of the English word may be… …   Etymology dictionary

  • caffeine — ► NOUN ▪ a compound which is found in tea and coffee plants and is a stimulant of the central nervous system. DERIVATIVES caffeinated adjective. ORIGIN French caféine, from café coffee …   English terms dictionary

  • caffeine — [ka fēn′, kaf′ēn΄] n. [Ger kaffein (now coffeïn, after ModL coffea, coffee); coined by F. F. Runge (1795 1867), Ger chemist < kaffee, coffee (< Fr café < It caffè, COFFEE) + in, INE3] a bitter, crystalline alkaloid, C8H10N4O2, present in …   English World dictionary

  • Caffeine — This article is about the stimulant drug. For other uses, see Caffeine (disambiguation). Caffeine Systematic (IUPAC) name …   Wikipedia

  • Caffeine — A stimulant found naturally in coffee beans, tea leaves, cocoa beans (chocolate) and kola nuts (cola) and added to soft drinks, foods, and medicines. A cup of coffee has 100 250 milligrams of caffeine. Black tea brewed for 4 minutes has 40 100… …   Medical dictionary

  • caffeine — caf|feine [ˈkæfi:n US kæˈfi:n] n [U] [Date: 1800 1900; : German; Origin: kaffein, from kaffee coffee , from French café] a substance in tea, coffee, and some other drinks that makes you feel more active →↑decaffeinated ▪ Avoid caffeine (=drinks… …   Dictionary of contemporary English

  • caffeine — caf|feine [ kæ,fin ] noun uncount a substance in coffee and tea that makes you feel awake. Drinks that have had the caffeine removed are decaffeinated or caffeine free …   Usage of the words and phrases in modern English

  • caffeine — UK [ˈkæfiːn] / US [ˈkæˌfɪn] noun [uncountable] a substance in coffee and tea that makes you feel awake. Drinks that have had the caffeine removed are decaffeinated or caffeine free …   English dictionary


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