caffeine (kăfēn`), odorless, slightly bitter alkaloid found in coffee coffee, 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. , tea tea, 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 cola cola or kola, tropical tree (genus Cola) of the family Sterculiaceae ( sterculia family), native to Africa but now grown in other tropical regions.
..... Click the link for more information. ), ilex plants (the source of the Latin American drink maté maté (mätā`, mătā`), yerba maté
..... Click the link for more information. ), and, in small amounts, in cocoa (see cacao cacao (kəkä`ō, –kā`–), tropical tree (Theobroma cacao
..... Click the link for more information. ). It can also be prepared synthetically from uric acid uric acid (y
..... 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 stimulant stimulant, 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
..... 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.

Bibliography

See B. A Weinberg and B. K. Bealer, The World of Caffeine (2001).

caffeine

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.

caffeine, caffein

a white crystalline bitter alkaloid responsible for the stimulant action of tea, coffee, and cocoa: a constituent of many tonics and analgesics. Formula: C₈H₁₀N₄O₂

caffeine (redirected from Guarnine)

Bibliography

caffeine

caffeine
(redirected from Guarnine)