Marijuana

The world’s most commonly used hallucinogenic drug that is derived from a plant (Cannabis sativa) containing delta-9 tetrahydrocannabinol (THC). Marijuana is usually smoked like a cigarette, but it also can be cooked into baked goods such as brownies or cookies, or brewed like a tea. THC is also contained in hashish, which is the resin from the plant. Hashish is usually smoked in a pipe. Other names for marijuana include grass, reefer, pot, and weed.

THC acts on cannabinoid receptors, which are found on brain cells in many places throughout the brain. These cells are found in areas involved in memory (the hippocampus), concentration (cerebral cortex), perception (sensory portions of the cerebral cortex), and movement (the cerebellum). When THC activates cannabinoid receptors, it interferes with the normal functioning of these brain areas.

In low to medium doses, marijuana causes relaxation, reduced coordination, low blood pressure, sleepiness, disruption in attention, and an altered sense of time and space. In high doses, it can cause hallucinations, delusions, impaired memory, and disorientation. The effects of marijuana begin within one to 10 minutes and can last from three to four hours.

Scientists have known for a long time that THC interacted with cannabinoid receptors in the brain, but they did not know why the brain would have such receptors. In 1992 scientists discovered anandamide, the brain’s own THC, but they are not yet sure what the function of this chemical might be in a normal brain. Experts do not agree about whether marijuana can produce addiction and whether it causes long-term mental problems. While there have been no documented cases of fatal overdoses produced by marijuana, there is a high level of tar and other chemicals in marijuana cigarettes; smoking the drug causes similar health problems to cigarette smoking. There is a bigger risk of lung problems and lung cancer later in life due to marijuana cigarette smoking.