 Marijuana |
| Marijuana is one of the world's most commonly used illegal drugs. There are approximatly 300 million users worldwide and 28 million users in the United States (Diaz, 1997). Marijuana comes from a plant called Cannabis sativa. The chemical in this plant that produces the altered states of consciousness is called "delta-9 tetrahydrocannabinol" or "THC". Marujuana is usually smoked like a cigarette, but it can also be cooked into baked goods like brownies or cookies or brewed like tea. THC is also contained in "hashish" (hash) which is the resin from the marijuana plants. Hash is usually smoked in a pipe. Other names for marijuana include: grass, pot, reefer and week. |
Effects of Marijuana on the Nervous System |
THC
acts on "cannabinoid" receptors which are found on neurons
in many places in the brain. These brain areas are involved in memory
(the hippocampus),
concentration (cerebral cortex), perception (sensory portion of the cerebral
cortex) and movement (the cerebellum, substantia nigra, globus pallidus).
When THC activates cannabinoid receptors, it interfers with the normal
functioning of these brain areas. In low to medium doses, marijuana causes:
In high doses, Marijuana can cause:
Scientists have known for a long time that THC interacted with cannabinoid receptors in the brain but did not know why the brain would have such receptors. In 1992, they found the answer...anandamide. Anandamide is the brain's own THC (just like "endorphine" is the brain's own morphine). Still, scientists are not sure what the function of anandamine is in the normal brain. The effects of marijuana start as soon as 1-10 minutes after it is taken and can last 3 to 4 hours or even longer. Experiments have shown that THC can affect two neurotransmitters: nonrepinephrine and dopamine. Serotonin and GABA levels may also be altered. Whether marijuana can produce addiction is controversial. Also controversial is whether marijuana causes long-term mental abnormalities. Only future research will give us the answers. It is interesting to note that there are NO documented cases of fatal overdose produced by marijuana. However, because there is a high level of tar and other chemicals in marijuana, smoking it is similar to smoking cigaretes. The lungs get a big dose of chemicals that increase the chances of lung problems and cancer later in life.In 1996, the Journal of the American Medical Association (JAMA, vol.207, pages 1349-1350) published a paper that described the psychoactive effects of catnip in people. People who smoked catnip were said to become happy and relaxed. Cat nip (from the plant Nepta cataria) does cause most cats to act strangely: they rollaround, shake their heads, rub against things, and try to get the plant all over their bodies. Interestingly, cats are only affected when they smell it- it has NO EFFECT if they eat it. It appears that catnip has little or no psychoactive effects in people. Actually, in the 1969 JAMA paper, the authors mislabeled the picture of marujuana and catnip. They labeled the pictures of marijuana as catnip and that of catnip as marijuana. |
Chudler, H. Eric.Neurosciences For Kids. Marijuana.1996-2006. Accessed
September 21, 2006. |
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