25.2 MB (367.3 KB compressed)
3475 x 2539 pixels
29.5 x 21.6 cm ⏐ 11.6 x 8.5 in (300dpi)
SCI-COMM STUDIOS / SCIENCE PHOTO LIBRARY SCI-COMM STUDIOS / SCIENCE PHOTO LIBRARY
Molecules of caffeine (left) and adenosine (right), computer artwork. Caffeine acts in the body as a central nervous system stimulant and is the world's most widely consumed psychoactive drug. Adenosine is an endogenous substance (produced naturally inside the body) and acts as a central nervous system inhibitor (depressant), with essentially opposite effects to caffeine.
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