Prior to the 1980s, cannabinoids were thought to produce behavioral and physiological effects through interaction with cell membranes rather than specific receptors. Since the 1980s, there has been a discovery of the first cannabinoid receptors and mounting evidence for many more. Two identified cannabinoid receptors are CB1 and CB2. CB1, the cannabinoid receptors in the brain, outnumber many other receptor types in the brain and help to control activity of most of the other neurotransmitters. They regulate things like alertness, temperature, or hunger by providing immediate feedback and regulating those systems in the body.
Our body produces molecules called endocannabinoids, that stimulate these receptors and are similar to molecules in the cannabis plant. The cannabis plant, which has been used by humans for more than 5000 years, provides its effects by utilizing this ancient cellular system.