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caffeine

Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is the world's most widely consumed psychoactive drug. Unlike many other psychoactive substances, it is legal and unregulated in nearly all parts of the world. There are several known mechanisms of action to explain the effects of caffeine. The most prominent is that it reversibly blocks the action of adenosine on its receptor and consequently prevents the onset of drowsiness induced by adenosine. Caffeine also stimulates certain portions of the autonomic nervous system. Caffeine is a bitter, white crystalline purine, a methylxanthine alkaloid, and is chemically related to the adenine and guanine bases of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). It is found in the seeds, nuts, or leaves of a number of plants native to South America and East Asia and helps to protect them against predator insects and to prevent germination of nearby seeds. The most well known source of caffeine is the coffee bean, a misnomer for the seed of Coffea plants. Beverages containing caffeine are ingested to relieve or prevent drowsiness and to improve performance.
Zuzia's coffee - Morning coffee is delicious try this today; D
                          
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Zuzia's coffee

Added 2 months ago by Zuzia

7 1

Coffee for two - Coffee, cups, hearts
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Coffee for two

Added 2 months ago by Ela

37

something sweet - a cup of coffee and a smiling ciacho
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something sweet

Added 3 months ago by stachna

36

Breakfast in Paris - colorful jigsaw puzzle
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Breakfast in Paris

Added year ago by andi

52

Puzzle-coffee - coffee jigsaw puzzle
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Puzzle-coffee

Added year ago by andi

24

something to eat - coffee prepared in this way tastes good
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something to eat

Added year ago by stachna

84

spożywka - a cup of coffee and sugar cubes
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spożywka

Added year ago by stabar

141

spożywka - cup with steaming coffee and coffee beans
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spożywka

Added year ago by stabar

57

spożywka - cup with coffee, cake and leaf
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spożywka

Added year ago by staszka

76

pełen relaks - z samego rana kawunia
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pełen relaks

Added year ago by Bożenka

19

herbatka - rozgrzewająca herbatka
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herbatka

Added over a year ago by stachna

139

dzień dobry - puzle na dzień dobry
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dzień dobry

Added over a year ago by Goska

45

Francuskie śniadanie - Ach, tak słodko chyba już nie bedzię
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Francuskie śniadanie

Added over a year ago by Gabrysia

689

kawa,kawusia pyszna, - kawa,kawusia pyszna,kawa,kawusia pyszna,
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kawa,kawusia pyszna,

Added over a year ago by Marysia

72

Filiżanka kawy - Ziarenka kawy, młynek i kawa w filiżance
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Filiżanka kawy

Added over a year ago by aberade

58