Cannabinoids are a diverse set of chemical compounds that bind to special receptors in the human body that make up what is known as the endocannabinoid system. The "lock and key" metaphor is often used to describe this process. The human body possesses specific binding sites "locks" on the surface of many cell types, and our body produces several endocannabinoids "keys" that bind to these cannabinoid receptors (CB) to activate or "unlock" them.
In 1992, researchers detected an endogenous substance that binds to cannabinoid receptors for the first time. This substance, known as anandamide, comes from the Sanskrit word "Ananda" for bliss and "amide" due to its chemical structure. A second endocannabinoid was discovered in 1995, 2-arachidonoylglycerol (2-AG). These two endocannabinoids are the best studied so far. Today, it is thought that about 200+ related substances exist, which resemble the endocannabinoids and complement their function in what has been termed the "entourage effect." Several endocannabinoids do not only bind to cannabinoid receptors, but also to a possible CB3 receptor (the GPR55 receptor), to vanilloid receptors and further receptors.
In addition to endocannabinoids, scientists have now identified cannabinoids found in the cannabis plant (phytocannabinoids) that work to mimic or counteract the effects of some endocannabinoids. Phytocannabinoids and terpenes are manufactured in resin glands (trichomes) present on the flowers and main fan leaves of late-stage cannabis plants. The amount of resin produced and its cannabinoid content varies by plant gender, growing conditions and harvesting time. The chemical stability of cannabinoids in harvested plant material is affected by moisture, temperature, light and storage, but will degrade over time in any storage conditions.
When a cannabinoid causes a receptor to act in the same way as it would to a naturally occurring hormone or neurotransmitter, then it is labeled "agonist." On the other hand, if the cannabinoid prevents the receptor from binding to the naturally occurring compound, thereby causing the resulting event (e.g., pain, appetite, alertness) to be altered or diminished, it is labeled "antagonist." Research is mounting to better understand how specific cannabinoids can unlock (or lock in some cases) specific receptors.
Over 100 phytocannabinoids have been identified in the cannabis plant, many of which have documented medicinal value. Most are closely related or differ by only a single chemical part. The most talked-about and researched cannabinoids found in the cannabis plant are tetrahydrocannabinol (THC) for its psychoactive properties ("high feeling") and cannabidiol (CBD) for its healing properties. Cannabinoids can be administered by smoking, vaporizing, oral ingestion, transdermal patch, intravenous injection, sublingual absorption or rectal suppository. (medicaljane.com)