The endocannabinoid system (ECS) is a biological system composed of endocannabinoids, which are endogenous lipid-based retrograde neurotransmitters that bind to cannabinoid receptors (CBRs), and cannabinoid receptor proteins that are expressed throughout the vertebrate central nervous system (including the brain) and peripheral nervous system. The endocannabinoid system remains under preliminary research, but may be involved in regulating physiological and cognitive processes, including fertilitypregnancypre- and postnatal development, various activity of immune system, appetitepain-sensationmood, and memory, and in mediating the pharmacological effects of cannabis
It has further been suggested that different endocannabinoids are known to influence  the striatum, this system is known to function in several other brain structures such as the nucleus accumbens, amygdala, hippocampus, cerebral cortex, cerebellum, ventral tegmental area (VTA), brain stem, and superior colliculus. Typically, these retrograde transmitters are released by the postsynaptic neuron and induce synaptic depression by activating the presynaptic CB1 receptors
Two primary cannabinoid receptors have been identified: CB1, first cloned in 1990; and CB2, cloned in 1993. CB1 receptors are found predominantly in the brain and nervous system, as well as in peripheral organs and tissues, and are the main molecular target of the endogenous partial agonistanandamide (AEA), as well as exogenous THC, the most known active component of cannabis. Endocannabinoid 2-arachidonoylglycerol (2-AG), which is 170-fold more abundant in the brain than AEA, acts as a full agonist at both CB receptors. CBD is a phytocannabinoid that acts as a rather weak antagonist at both CBRs and a more potent agonist at TRPV1 and antagonist at TRPM8. It is also known to be a negative allosteric modulator at CB1. CBD has been found to counteract some of the negative side effects of THC
Terpenes (/ˈtɜːrpiːn/) are a large and diverse class of organic compounds, produced by a variety of plants, particularly conifers, and by some insects. They often have a strong odor and may protect the plants that produce them by deterring herbivores and by attracting predators and parasites of herbivores. Although sometimes used interchangeably with "terpenes", terpenoids (or isoprenoids) are modified terpenes as they contain additional functional groups, usually oxygen-containing. Terpenes are hydrocarbons.
Terpenes are the major components of rosin and of turpentine produced from resin. The name "terpene" is derived from the word "terpentine", an obsolete spelling of the word "turpentine". Terpenes are also major biosynthetic building blocks. Steroids, for example, are derivatives of the triterpene squalene.
Terpenes and terpenoids are the primary constituents of the essential oils of many types of plants and flowers. Essential oils are used widely as fragrances in perfumery and traditional medicine, such as aromatherapy. Synthetic variations and derivatives of natural terpenes and terpenoids also greatly expand the variety of aromas used in perfumery and flavors used in food additives. Vitamin A is a terpenoid.