The Endocannabinoid System

The human body is kept in homeostasis, or biological balance, through many complex ‘cell-signalling’ or cell communication systems. These systems communicate via molecular messengers (such as hormones) binding to specific receptors on our cells.

All drugs, including those sourced from plants, interact with biological systems that already exist in our body.

The endocannabinoid system was only recently discovered and has only been investigated for the past 30 years.1 Our understanding of the endocannabinoids system is still developing but its main function appears to be maintaining homeostasis and regulating many biological functions.2

Endocannabinoids are molecular messengers made by our own bodies that interact with molecular targets of the endocannabinoid system to regulate homeostasis. The two best-known endocannabinoids are AEA and 2-AG:1

AEA (anandamide)

2-AG (2-arachidonoylglycerol)



Endocannabinoids bind to specific molecular targets known as the cannabinoid receptors, CB1 and CB2, which are found on the cells of many different organs:

Cannabinoid receptors:

Type 1 cannabinoid receptor (CB1)

Type 2 cannabinoid receptor (CB2)

Endocannabinoids binding to the cannabinoid receptors on a human body cell

The figure below shows the location and action of the endocannabinoid system throughout the body:

Figure adapted from Maccarrone M, et al. 20151 and Zou S, et al. 2018.2


  1. Maccarrone M, et al. Endocannabinoid signaling at the periphery: 50 years after THC. Trends Pharmacol Sci. 2015; 36(5): 277-296. doi:10.1016/
  2. Zou S, et al. Cannabinoid receptors and the endocannabinoid system: Signaling and function in the central nervous system. Int J Mol Sci. 2018; 19(833). doi:3390/ijms19030833.