Endocannabinoid system (ECS)
ECSThe endocannabinoid system is a signaling network of receptors, lipid messengers made by the body and the enzymes that build and break those messengers down.
Its receptors are CB1, concentrated in the brain and peripheral nerves, and CB2, concentrated on immune cells. Its messengers, called endocannabinoids, are anandamide and 2-arachidonoylglycerol, both derived from cell-membrane fats and made on demand rather than stored. The enzymes FAAH and MAGL clear them within minutes. The system was identified while researchers were tracing how THC acts on the body, and it is now understood as a feedback mechanism that helps neurons and immune cells adjust the strength of the signals they send and receive.
Because CB1 receptors are widespread, the system touches appetite, memory, pain perception, mood, sleep and immune tone, which is why it is sometimes described as helping maintain homeostasis. That breadth is also why claims about it are easy to overstate. CBD influences several parts of this network indirectly in laboratory studies, but how those actions play out in living people is an active area of research with few settled answers.