According UCLA HEALTH, "In the 1990’s, scientists discovered endocannabinoids, the natural cannabis-like molecules produced by the human body. Scientists began to realize cannabis exerted its effects, in part, by mimicking our endocannabinoids. It appears the main function of the endocannabinoid system is to maintain bodily homeostasis—biological harmony in response to changes in the environment.
Research initially suggested endocannabinoid receptors were only present in the brain and nerves, but scientists later found that the receptors are present throughout the body, including our skin, immune cells, bone, fat tissue, liver, pancreas, skeletal muscle, heart, blood vessels, kidney, and gastrointestinal tract.11 We now know the endocannabinoid system is involved in a wide variety of processes, including pain, memory, mood, appetite, stress, sleep, metabolism, immune function, and reproductive function.12,13 Endocannabinoids are arguably one of the most widespread and versatile signaling molecules known to man. https://www.uclahealth.org/cannabis/human-endocannabinoid-system