Get this: There is a system in our bodies that produces naturally occurring endogenous cannabinoids and is designed to accept plant-based cannabinoids. Let that sink in. Your body was designed to accept cannabis.
Yes. The endocannabinoid system (ECS) was discovered in the early '90s by Israeli Professor Raphael Mechoulam—the researcher who also discovered THC in 1964—of the Center For Research On Pain. Mechoulam found two main cell receptors, cannabinoid 1 (CB1) and cannabinoid 2 (CB2), in a series throughout the brain and every major organ. CB1 receptors are more concentrated in the nervous system and CB2 receptors are are concentrated on immune cells, in the gastrointestinal tract and in the peripheral nervous system.
These receptors are keyed to accept what Mechoulam called “endocannabinoids” (EC), named after the chemical components in cannabis. There are six of these compounds, produced naturally by the body in a process similar to endorphin production: anandamide, 2-
The EC molecules act as chemical signals which regulate physiological functions by interfacing with the receptors. Through these chemical messages, the ECS tells the body when to start and stop certain processes pertaining to sleep, mood, appetite, pain, memory, motor control, immune function, reward systems, temperature regulation and others.
Sound familiar? Those are all areas where cannabis is said to have the most profound medical effects. It's no mystery why, either. The reason EC molecules were named after cannabinoids is because they are processed by the receptors in much the same way. Cannabinoids are incredibly similar in shape to EC molecules, which makes a receptor treat the psychocannabinoid like a natural one.
THC is specifically shaped to fit CB1 receptors (those are in the brain, remember), explaining why it effects users psychoactively, while CBD is keyed to CB2 receptors (the ones in the immune and digestive systems). This can go a long way in understanding why THC is so good at reducing pain. It actually goes into the brain and turns down the user's perception.
(It should be noted here that CB1 receptors are not found in the part of the brain that regulates heart rate and respiration, which is why there is no lethal dosage for THC as there is with traditional pain-killers like opioids or analgesics.)
By being similar in shape to endocannabinoids, THC and other psychocannabinoid molecules hack the ECS and directly instruct your body on how these various systems should be operating.
What's crazy is that by comparing the genetics of different species, it has been estimated that the endocannabinoid system evolved in primitive animals over 600 million years ago. Meaning it was around before humans were.
I was explaining this (poorly) to a friend of mine who still has reservations about cannabis use, medical or otherwise. “So smoking weed interrupts your body's natural flow?” she asked. “See? That stuff ain't good for you.”
At the time, I just rolled my eyes, but I thought of this answer later: “Another way to look at it would be that your idiotic body keeps hurting, even though you keep telling it to stop. And cannabis is like a drill sergeant you can send in that will start throwing orders around and asking questions like, 'What is your major malfunction?'”
A better (or at least more mature) way to look at it, though: Your “natural flow” in this context is the state where all of your body's functions are being regulated by endogenous chemicals, without outside influence. If introducing cannabis into that system is “interrupting” the flow, then so is introducing water, air, vitamin D from sunlight, any sort of psychotropic food source (all of them), etc. I'm sure you can see where I'm going with this. A body might seem to be a closed off system, but it's not. It relies on a number of outside influences. If you try to live in a vacuum, you will die.
There obviously has to be a hierarchy established, a way to differentiate between things that are bad to introduce (like poison) and things that are good (like food). But no matter what, any substance that enters your body will “interrupt the natural flow.”
And guess what? If that “natural flow” involves pain and discomfort, then I say interrupt the hell out of it (within reason, of course). That's what medicine is for.