The endocannabinoid system (ECS) is an internal homeostatic regulatory system that serves to limit excitatory neurotransmission. It consists of four components:
1) G protein-coupled cannabinoid CB1 and CB2 receptors;
2) endogenous endocannabinoids that target these receptors, and possibly others;
3) enzymes that catalyze endocannabinoid biosynthesis and metabolism; and
4) mechanisms involved in cell accumulation of specific endocannabinoids.
Endogenous endocannabinoids play a fundamental role in regulating pleasure, relaxation, memory, thinking, concentration, body movement, awareness of time, appetite, pain, and sensory processing and brain development. They are produced on-demand in response to excitatory neurotransmission and travel in retrograde fashion to inhibit further neurotransmitter release.
Research done on the system has shown that the ECS has receptors throughout the body, including in the brain, organs, connective tissues, glands, and immune cells. Because phytocannabinoids are insoluble in water, their absorption is limited in the body.