caffeine(redirected from Guarnine)
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caffeine(kăfēn`), odorless, slightly bitter alkaloid found in coffeecoffee,
a tree, its seeds, and the beverage made from them. The coffee tree, a small evergreen of the genus Coffea, has smooth, ovate leaves and clusters of fragrant white flowers that mature into deep red fruits about 1-2 in. (1.27 cm) long.
..... Click the link for more information. , teatea,
tree or bush, its leaves, and the beverage made from these leaves. The plant (Camellia sinensis, Thea sinensis, or C. thea) is an evergreen related to the camellia and indigenous to Assam (India) and probably to parts of China and Japan.
..... Click the link for more information. , kola nuts (see colacola
tropical tree (genus Cola) of the family Sterculiaceae (sterculia family), native to Africa but now grown in other tropical regions. The fruit is a pod containing seeds from which is obtained caffeine, an alkaloid that functions as a stimulant.
..... Click the link for more information. ), ilex plants (the source of the Latin American drink matématé
, yerba maté
, or Paraguay tea,
evergreen tree (Ilex paraguariensis) of the family Aquifoliaceae (holly family). From ancient times Native Americans and now millions of Argentines and others in South America have made a tea (also
..... Click the link for more information. ), and, in small amounts, in cocoa (see cacaocacao
, tropical tree (Theobroma cacao) of the family Sterculiaceae (sterculia family), native to South America, where it was first domesticated and was highly prized by the Aztecs. It has been extensively cultivated in the Old World since the Spanish conquest.
..... Click the link for more information. ). It can also be prepared synthetically from uric aciduric acid
, white, odorless, tasteless crystalline substance formed as a result of purine degradation in man, other primates, dalmatians, birds, snakes, and lizards. The last three groups of animals also channel all amino acid degradation into the formation of glycine, aspartic
..... Click the link for more information. . While relatively harmless, it is the most commonly used mind-altering drug in the world. When used in moderation, caffeine acts as a mild stimulantstimulant,
any substance that causes an increase in activity in various parts of the nervous system or directly increases muscle activity. Cerebral, or psychic, stimulants act on the central nervous system and provide a temporary sense of alertness and well-being as well as
..... Click the link for more information. to the nervous system, blocking the neurotransmitter adenosine and resulting in a feeling of well-being and alertness. It increases the heart rate, blood pressure, and urination and stimulates secretion of stomach acids; excessive intake can result in restlessness, insomnia, and heart irregularities. The effects of caffeine vary from person to person, as people excrete it at different rates. Physical dependence and unpleasant symptoms upon withdrawal (headache, fatigue, depression) are common in regular caffeine users.
See B. A Weinberg and B. K. Bealer, The World of Caffeine (2001).
a central nervous system stimulant; trimethylxanthine, an alkaloid found in tea leaves, coffee beans, and kola nuts and obtainable synthetically.
Caffeine is administered in tablet form in cases of central nervous system depression, weak cardiac activity, narcotic intoxication, hypotonia, and migraine. A solution of caffeine and sodium benzoate, containing 38 percent pure caffeine and administered subcutaneously, has similar pharmacological properties and indications.