The Endocannabinoid System

What is the Endocannabinoid System?

The endocannabionid system or ECS is an very important physiological system that is present in our bodies for the regulation and maintenance of our health. Besides humans it is also present in all vertebrates and in some lower forms of life such as sea squirts and flat worms.

The role of this system is immense and it regulates important functions in our body such as appetite, sleep, reproduction, fertility, forgetting, protection and stress prevention. It also plays a major role in the bodies energy intake, storage and processing, helping the immune system and decide the fate of cells, especially unhealthy ones.

It is composed of signalling molecules that bind to specific receptors. These molecules are called endocannabinoids (“endo” meaning “within” as we make them in our bodies) and are basically lipids(fats) that are produced on demand when needed. They are not stored in vesicles, as many other neurotransmitters are, but can be synthesized directly from the phospholipids in our cell membranes.


The most common endocannabinoids are anandamide (N‐arachidonoyl‐ethanolamine)  and AG-2 (2‐arachidonoyl‐glycerol) . Others have been found, such as noladin ether and virodhamine, but the most abundant and studied remain these two.

There wouldn’t be much sense in having a signalling molecule without a place where it could deliver its signal. This place is called the receptor as the molecule can bind on the receptor. These receptors are named endocannabinoid receptors and so far two have been discovered CB1 and CB2. These two receptors have the similar structure, they are G protein receptors, with the main difference being in the place where they are expressed and the effects they have in these cells.

CB1 and CB2 Receptors

CB1 receptors are found mainly in the central nervous system, connective tissues, glands and gonads(reproductive organs). They have the highest concentration of any receptor in our brain regions like the cerebral cortex, hippocampus  basal ganglia, cerebellum, amygdala and nucleus accumbens. They are however not found on the brain stem, where there are centers that monitor our breathing and heart beat.

CB2 receptor are mainly found in our lymphoid organs(spleen, thymus, tonsils, bone marrow, leukocytes)  and also in other tissues(pancreas, macrophages). They are not fixed and are made and expressed when there is something wrong with that tissue like infections or injuries.

The Role of The ECS

So what is the role of the ECS? In one work homeostasis. Homeostasis is the maintenance of a stable internal (cellular) environment in a dynamic ever changing external environment. Balance is the prerogative of this system and if anything is out of balance it will try to restore its original state.

This is applied on a cellular level, if a cell becomes cancerous and starts behaving abnormally the endocannabinoids will bind to it and start an irreversible cascade of reactions that ultimately leads to programmed cell death (apoptosis) of the abnormal cell.

On a tissue level, if there is an injury, swelling, pain and inflammation starts occurring. Endocannabinoids will instruct immune cells and nerve cells to down-regulate the response lowering the firing of pain signals, reducing the swelling and preventing immune cells from releasing pro-inflammatory molecules.

These are just two examples of the role of the ECS but it is essential in almost every aspect of our complex living machine, coordinating the interactions between our organs, nervous system, endocrine system and immune system.

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