If there's one thing that Stuff You Should Know is here for, it's explaining everything. So if you've ever smoked pot and found yourself couch-locked or unreasonably suspicious of your cat and wondered what exactly is going on, prepare to know.
In your body you have two types of receptors for pot, both of which make up the endocannabinoid system. The CB1 receptor is found in the brain and the CB2 receptor is found around the body. We know about these receptors and the system they comprise thanks to pot. Back in the 1960s, THC was first isolated and over the decades it was reverse engineered from there. In 1992, the first of the body's natural cannabinoids, the ones that are intended to go into the endocannabinoid receptors in our body and brains, was isolated. The Israeli researcher who discovered it named it anandamide, which in Sanskrit means "internal bliss".
Because of research into the physiological effects of marijuana, the endocannabinoid system was uncovered and it allowed us a glimpse into how the brain achieves its constant goal: homeostasis. It's an evolutionarily ancient and clever system found in all vertebrates and organisms as primitive as nematodes.
Your brain communicates with the rest of your body - from directing the muscles in your arm to grasp a coffee mug to thinking about how you feel about your life prospects - through transmissions across neuron. Neurons transmit information when electrical charges cause neurotransmitters to be released into the gap between neurons known as the synapse. These chemicals are picked up by receptors in other neurons and, depending on the context of the chemical and the location of the receptors in the body or the brain, a physiological process is carried out. You blink, you eat, you feel good about things.
The endocannabinoid system is responsible for regulating these transmissions in order to maintain homeostasis. It prevents your systems from going haywire or becoming sluggish by working retroactively; where neurotransmitters travel from one neuron to another, the endocannabinoids like anandamide move backward and act as dimmer switches on your neurons, causing them to fire less frequently and less intensely.
When you smoke pot, the THC - a type of phytocannabinoid or plant-based cannabinoid - contained in the trichomes of the pot (the little, clear, sticky hairs that can give pot a hazy appearance) is carried into your lungs where it is transferred into your blood stream via gas exchange at the alveoli. As your oxygen-deprived blood comes to the lungs to be replenished, that dose of oxygen also contains a healthy measure of THC as well and it's taken along for the ride in your bloodstream. The THC travels throughout the body, including to your brain where it binds to endocannabinoid receptors. When THC in essence sticks to your brain, it essentially hijacks the endocannabinoid system and prevents it from regulating for homeostasis.
It's here that all manner of crazy stuff happens to you. Since endocannabinoid receptors are found in many disparate regions of the brain, the effects of THC can create numerous symptoms. Your hippocampus, which is responsible for sorting incoming information into new memories is interfered with and so you have trouble remembering or learning when high. Your amygdala, responsible for regulating emotions, has trouble maintaining normal function and so you may experience euphoria or anxiety or both. Dopamine, a primary chemical for producing both feelings of pleasure and psychosis, is released and higher levels of it can lead to feelings of paranoia. In fact, the basomedial amygdala in particular is targeted by THC and its function is heightened. So the region's normal responsibility of teaching to fear dangerous or threatening situations works overtime and so we suddenly don't like how that cat is looking at us.
You executive function may be impaired and thus so may your judgment. Your basal ganglia and cerebellum are both operating in abnormal states so your movement and coordination aren't as graceful as usual. Your perception of time may slow, your mouth may hang open and then, at some point, food will seem very, very appealing to you. The munchies, as they're called, develop because you have receptors for ghrelin, which is released when you're hungry. Ghrelin, as you may have guessed, is mediated by endocannabinoids in your hypothalamus and THC mimics them, causing the release of ghrelin. Food takes on a suddenly irresistible complexion.
There you have it, your brain on drugs.
We should say that it is because of all of this hijacking of the normal functions of these different brain regions that researchers have concluded through numerous studies that because the adolescent brain is developing still this makes it particularly susceptible to what amounts to long-term brain damage from using marijuana. Two years of heavy, regular pot smoking was found in a 2013 study to be associated with shrinkage among subcortical regions of the brain, like the thalamus, that are used in working memory. So, in effect, adolescents smoking pot can develop a learning disability from it. This is, perhaps in addition to it being illegal, why kids are told not to smoke pot, not to be a bum them out but because adolescence is precisely the wrong stage of cognitive development for introducing regular, large doses of THC to the brain. Food for thought. What's ironic, of course, is that teenagers are by far the largest group of regular marijuana users in the U.S.
And if all of this was up your alley, then, buddy, check out our entire podcast episode on pot, How Marijuana Works.