Bongs & Pipes
We have our own cannabinoid receptors because the human body creates its own version of cannabis compounds called endocannabinoids which is mainly our own version of THC.
The Endocannabinoids system is a neurotransmitter network that acts as a homeostatic regulator. This is a fancy term for a system that helps maintain optimal balance in the body.The ECS helps coordinate messages between the brain and the body, ensuring that both respond appropriately to both internal and environmental stimuli.
A decent amount, but not nearly enough. We do know that the brain has a high density of CB1 receptors (I suspect we'll find more CB2 receptors and yet-to-be named cannabinoid receptors as well).
The Brainstem is said to have a relatively low density of CB1, potentially explaining the lack of vomitting/breathing overdose concerns that we see with other drugs.
We also know that CB1 receptors are regulators - they are not involved directly in signal transmission. They actually respond to signals, releasing endogenous cannabinoids from the post-synaptic terminal and traveling in a retrograde manner to the pre-synaptic terminal. This then leads to a reduction in the likelihood of further signals. I like to think of these receptors as activity-gates, opening and closing to help manage signals.
To show an example of how important this system is, look to autism. People with autism tend to be flooded with sensory stimuli, being easily overwhelmed by this. Imagine feeling everything at once - all the smells, sights, physical sensations, and all of that at once. Normally our brain manages these signals to emphasize the important once and reduce the rest. The cannabinoid system is likely a major driver of this process
Woah man - you should teach on this subject!