How Marijuana Works

Rumour has it that marijuana has some pretty interesting effects on the human brain, but how could plant smoke affect our physiology? Well, it's all to do with a case of mistaken identity. Logan Wright goes in search of cells that get duped by dope into having a high old time.

Known variously as marijuana, ganja, cannabis, pot, jays, joints and Mary Jane, the product derived from the cannabis plant is undoubtedly the most popular illicit recreational drug in the world; hence its countless pet names. It can be taken in a variety of creative ways including smoking, eating and drinking, even has incarnations in gum or brownies form.

THC, or tetrahydrocannabinol if you prefer, is a compound within the cannabis plant that, like nicotine or caffeine, may have evolved to ward off herbivores. Its strong psychoactive properties, however, have proven rather seductive to the international drugs scene.

The parts of the brain most affected by marijuana. Click to enlarge.

Once it reaches the bloodstream, THC takes only a few seconds to reach the brain, where it passes itself off as a neurotransmitter - the chemicals which carry messages between neurons in the brain. THC is shaped much like a neurotransmitter called anandamide, which means it can sneak itself into the brain’s anandamide receptor proteins and start to cause mischief. With THC’s spanner in the works, some of the brain’s normal functions really begin to waver.

The receptor proteins are located primarily in three areas of the brain: the hippocampus, responsible for short term memory; the cerebellum, an area controlling coordination; and the basal ganglia, which manages unconscious muscle movement. These are the functions that are altered by THC’s presence, which is why a marijuana user will typically experience impaired coordination, memory lapses, paranoia and altered perception, as well as feeling their heart quicken.

THC's chemical structure. Click to enlarge. Why don't you download the structure, draw a picture and enter it to the THC gallery?

One thing scientists do not thoroughly understand is how THC interacts with dopamine, the chemical that is well known for generating feelings of pleasure and motivation. It’s thought that when THC activates receptor proteins a signal is sent to nearby dopamine terminals in the brain. These then begin to produce inordinate amounts of dopamine, triggering that contented feeling known to so many politicians.

The health effects of marijuana are hotly contested. There is good evidence that it is effective a treating the symptoms of Parkinson’s disease and is used by many people as a treatment for a variety of ills and aches.

However, although it’s generally accepted to be safer than heroine or cocaine, marijuana may have several potential long term effects, which are less helpful. The drug has been linked to an increased incidence of schizophrenia and other mental illnesses. It is also referred to as a “gateway drug” because many marijuana users move from it to more dangerous drugs in search of a more powerful experiencer. For those particularly enamored with the drug’s effects, however, there is consolation: some believe that marijuana use may lead to an eventual perma-high.


Cannabis trivia:

• Archaeologists have reported that marijuana was one of the first plants cultivated by humans. It was being used 10,000 years ago for linen, paper, and garments. In China and India, it was being smoked as early as 2700 BC.
• The Ancient Greek historian Herodotus mentions that Scythian tribes used to pile cannabis leaves on to bonfires during wild festivals.
• George Washington, the first US president, grew cannabis, declaring "Make the most you can of the Indian Hemp seed and sow it everywhere."
• In Vietnam, where cannabis grows wild and free, people rarely smoke it themselves. Instead they feed it to their pigs, who get the serious munchies. The result is that the farmers produce some very fat, and very chilled out, pigs.

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