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There are major differences in the metabolism of morphine and the illegal drug heroin. Morphine mostly produces its CNS effects through m-receptors, and at k- and d-receptors. Heroin has a slight affinity for opiate receptors. Most of its actions are due to metabolism to active metabolites (6-acetylmorphine, morphine, and morphine-6-glucuronide).
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
The Romans did not use numerals to indicate fractions but instead used words to indicate parts of a whole.
The Babylonians wrote numbers in a system that used 60 as the base value rather than the number 10. They did not have a symbol for "zero."
More than 150,000 Americans killed by cardiovascular disease are younger than the age of 65 years.