For years the scientists have known that certain compounds in the cannabis plant, known as phytocannabinoids, have noticeable effects on functions of the human body.  However they didn’t fully understand the reasons behind these effects. In the 1990’s scientists discovered that the brain itself produces compounds similar to phytocannabinoids, which are known as endogenous cannabinoids. These substances bind to specific sites in the brain known as cannabinoid receptors. 
Cannabinoid receptor sites are located throughout the body, from the brain to the connective tissue. Cannabinoids bind to or stimulate these sites in order to regulate the function of the muscular system, immune system, nervous system and more. Scientists have discovered that cannbinoids stimulate two main receptors in the body; called CB1 and CB2.
CB1 Receptors
Cannabinoid receptor type 1 is found primarily in the central nervous system, although some of these receptors are also present in the peripheral tissues, including the endocrine glands, spleen, heart and other locations. They respond to endogenous cannabinoids, such as anandamide, as well as external cannabinoids, such as CBD and THC.
CB2 Receptors
Cannabinoid receptor type 2 is found only in peripheral tissues and is not typically found in the central nervous system. CB2 receptors respond to endogenous cannabinoids, as well as CBD, THC and other phytocannabinoids.
Together, CB1 and CB2 are responsible for regulating neuro-hormones in the body. These receptors have an active role in many different physiological processes, including memory, mood, sensations of pain, and appetite regulation. When cannabinoids are introduced to the receptors, the receptors activate and produce physiological changes and symptom relief.
Medical Research and Implications
Research about the effects of phytocannabinoids on the body’s cannabinoid receptors is ongoing. However scientists have already learned that certain cannabinoids, such as THC, bind directly with a specific type of receptor. In the case of THC, CB1 receptors are affected. Cannabidiol or CBD, does not bind directly with either CB1 or CB2 receptors. Instead, it stimulates both types of receptors.
Cannabinoid receptors are responsible for regulating the balance of many everyday functions in the human body. These receptors are activated when cannabinoids are introduced into the body from external sources, such as CBD sublingual drops. This system can be activated in order to alleviate certain symptoms. According to Project CBD, cannabis oil may be helpful in treating a variety of health conditions including osteoporosis, Parkinson’s disease, seizures, glaucoma, high blood pressure, movement disorders, anxiety, obesity, ALS and various psychological issues.