77 lines
4.3 KiB
Plaintext
77 lines
4.3 KiB
Plaintext
marijuana
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{mar-i-wahn'-uh}
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Marijuana (also spelled marihuana) is the common name given to any
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DRUG preparation from the hemp plant, Cannabis sativa. Various forms of
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this drug are known by different names throughout the world, such as kif
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in Morocco, dagga in South Africa, and ganja in India. Hashish refers to a
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dried, resinous substance that exudes from the flowering tops of the
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plant. In Western culture, cannabis preparations have acquired a variety
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of slang names, including grass, pot, tea, reefer, weed, and Mary Jane.
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Cannabis has been smoked, eaten in cakes, and drunk in beverages. In
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Western cultures marijuana is prepared most often as a tobaccolike mixture
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that is smoked in a pipe or rolled into a cigarette.
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One of the oldest known drugs, cannabis was acknowledged as early as
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2700 BC, in a Chinese manuscript. Throughout the centuries it has been
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used both medicinally and as an intoxicant. The major psychoactive
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component of this drug, however, was not identified until the mid-1960s;
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this ingredient is tetrahydrocannabinol, commonly known as THC. At
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present, other cannabinoids have been isolated and their possible
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biochemical activities are being explored. Psychoactive compounds are
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found in all parts of the male and female plant, with the greatest
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concentration in the flowering tops. The content of these active compounds
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varies greatly from plant to plant, depending on genetic and environmental
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factors.
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Marijuana has its major physiological effects on the cardiovascular
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and central nervous systems; these effects are primarily sedative and
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hallucinogenic. Low doses psychologically produce a sense of well-being,
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relaxation, and sleepiness. Higher doses cause mild sensory distortions,
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altered time sense, loss of short-term memory, loss of balance, and
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difficulty in completing thought processes. Even higher doses can result
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in feelings of depersonalization, severe anxiety and panic, and a toxic
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psychosis, along with hallucinations, loss of insight, delusions, and
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paranoia. Physiologically, the heart rate increases and blood vessels of
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the eye dilate, causing reddening. A feeling of tightness in the chest
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and a lack of muscular coordination may also occur. Research suggests that
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marijuana smoke may have a long-term harmful effect on the lungs. Users
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may develop tolerance for the drug, but studies have not determined
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whether physical dependence results.
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The use of marijuana as an intoxicant in the United States became a
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problem of public concern in the 1930s. Regulatory laws were passed in
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1937, and criminal penalties were instituted for possession and sale of
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the botanical drug. In 1968 the possession and sale of THC, the
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psychoactive chemical component, was restricted to research. Despite
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these measures, marijuana continued to be widely used in succeeding
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decades as various groups sought to decriminalize its possession. A
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survey in the late 1970s indicated that at least 43 million Americans had
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tried the drug. In the 1980s, however, surveys of high school and college
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students showed that marijuana use was steadily declining. The number of
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high school seniors for instance, who had tried the drug decreased from
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50.8 percent in 1979 to 33.1 percent in 1989.
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Conversely, cultivation of marijuana in the United States is
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increasing, accounting for 25 percent of the U.S. domestic market by
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1990. Moreover, new growing practices have increased the potency (THC
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content) of domestically produced marijuana five fold or more, causing
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concern among drug-abuse experts about adverse effects from higher THC
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doses.
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Medically, marijuana and THC preparations are sometimes used to treat
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GLAUCOMA, because they help to reduce pressure within the eye. In 1985
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the Food and Drug Administration also approved the use of synthetic THC
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(dronabinol) for treating the nausea and vomiting that can accompany
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cancer chemotherapy. It apparently acts by binding to opiate receptors in
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the medulla of the brain.
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Charles W. Gorodetzky
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Bibliography:
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Abel, Ernest L., A Marihuana Dictionary (1982); Gold, M.S., Marijuana
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(1989); Himmelstein, J.L., The Strange Career of Marihuana (1983);
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Kanzukol, Paul, and Musty, Richard, eds., Marijuana (1989); Nahas, Gabriel
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G., Marihuana in Science and Medicine (1984).
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