Marijuana (also spelled marihuana) is the common name given to any drug preparation from the hemp plant, Cannabis Sativa. Various forms of this drug are known by different names throughout the world, such as kif in Marocco, dagga in South Africa, and ganja in India. Hashish refers to a dried, resinous substance that exudes from the flowering tops of the plant. In Western culture, cannabis preparations have acquired a variety of slang names, including grass, pot, tea, reefer, weed, and cakes, and drunk in beverages. In Western cultures marijuana is prepared must often as a tobaccolike mixture that is smoked in a pipe or rolled into cigarette.
The major psychoactive component of marijuana is tetrahydrocannabinol (THC). Other cannabinoids have also been isolated, and their biochemistry is being studied. Psychoactive compounds are found in all part of the plant, with the greatest concentration in the flowering tops. The content of these compounds varies greatly from the plant to plant, depending on genetic and environmental factors.
Marijuana has its major physiological effects on the cardiovascular and central nervous systems; these effects are primarily sedative and hallucinogenic. Low doses psychologically produce a sense of well being, relaxation and sleepiness. Higher doses causes mild sensory distortions, altered time sense, loss of short term memory, loss of balance, and difficulty in completing thought processes. Even higher doses can result in feelings of depersonalization, severe anxiety and panic, and a toxic psychosis, along with hallucinations, loss of insight, delusions, and paranoia. Physiologically, the heart rate increases and blood vessels of the eye dilate, causing reddening. A feeling of tighness in the chest and a lack of muscular coordination may also occur. Research suggests that marijuana smoke may have a long term harmful effect on the lungs. Users may develop tolerance for the drug, but studies have not determined whether physical dependence results.
Medically, marijuana and THC preparations are sometimes used to treat Glaucoma, because they help to reduce pressure within the eye. The US. Food and Drug Administration has also approved the use of synthetic THC for treating the nausea and vomiting that can accompany cancer chemotherapy.