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Endo-cannabi- what?! An Introduction to the Endocannabinoid System

Updated: Mar 2, 2022

What is the “endo-cannabinoid system”? It has “cannabinoid” (aka cannabis, aka weed, aka pot, aka… you get the idea) in the name. But what exactly is it and what does it do? Well, it’s actually one of the most prevalent biological systems in not only humans, but in all animals. Learn more about the endocannabinoid system in this introductory article and stay tuned for a series of body system-specific articles in the future!

The Endocannabinoid System (ECS)

The prefix “endo” indicates that the endocannabinoid system (ECS) is in the body. This system is found not only in humans, but all mammals, and researchers have found that its parts are chemically analogous to those in the cannabis plant. You might be asking, “Wait, what?! I have weed inside me?” Not exactly but read on to learn more.

Our ECS is mostly composed of 2 parts: receptors and endocannabinoids. A receptor is a protein molecule to which hormones, drugs, and other molecules can bind. We have receptors all over our bodies. Endocannabinoids are fat-based neurotransmitter molecules that the body makes moment-to-moment, as needed. (Neurotransmitters are chemical messengers that send signals between the nerves). They are similar to cannabinoids (what’s found in cannabis), except that they’re produced inside our bodies. Certain endocannabinoids and receptors have a “lock-and-key” type of fit, so that when a correct pair binds, the body experiences a specific type of change.

Scientists have identified 2 major endocannabinoids so far: 2-arachidonoylglycerol (2-AG) and anandamide (AEA), which means “bliss” in Sanskrit.

In the ECS, the most found receptors are CB1 and CB2. These can be found throughout the body in places like the brain, cardiovascular, musculoskeletal, digestive systems, and everywhere in between. So, when the endocannabinoids (2-AG and AEA) are made they travel and bind to these receptors, which then signal different systems, ultimately affecting many things like sleep, hunger, inflammation, etc.

Researchers have recently noted that the CB1 receptor, specifically, is probably the most abundant receptor in the body. And because the endocannabinoids (remember they are chemical messengers) bind these abundant receptors, the ECS must play a large role in everyday functioning. Who would have ever thought that something with a root of “canna” would be essential for life?! (Ok, maybe some of you did.)

Unfortunately, the ECS was only discovered in the 1990s, which is very recent compared to other major body systems we’ve known about forever (consider the fact that human dissections became normalized in 1340, but some anatomical studies go back as far as the 3rd century BCE). Compared to some well-studied body systems, researchers know next to nothing about the ECS and its overall role in the body. In order to learn more, researchers must look closely at the specific interactions between environmental changes, the ECS and the functioning of all the other body systems.

Before we touch on different body systems, it’s important to first understand how the body reacts to external stimuli in general, which can be explained by the nervous system.

The Nervous System

The human nervous system is made of neurons (nerve cells) that compose the brain, spinal cord, and a complex network of neurons weaved throughout the body. The brain can be thought of as a control center, with the spinal cord representing an interstate highway. Neurons relay information and instructions to/from the brain and different parts of the body using the spinal cord as transportation. This communication allows the body to make changes when needed for everyday functioning and beyond.

Let’s learn more about communication by considering inputs and outputs. As we all know, the human body is equipped with five basic senses: touch, taste, sight, smell, and hearing. When something in the environment triggers one of the five senses, the body immediately has a sensory input. Consider getting pinched on the arm. The pinch sensors or receptors alert adjacent neurons and carry info to the spinal cord (where it connects with another neuron) and then up to the brain. The brain internally discusses this information using its own network of neurons… information like how much the pinch hurts, how angry you should be toward the person who pinched you, etc. In less than a millisecond the brain will send outgoing information about how to react.

Output information flows in the opposite direction… from the neurons in the brain back to those in the spinal cord. From there, the spinal cord neurons relay information for action. Once the information has traveled to its intended destination, the body will respond. For a pinch, maybe the response will be to grab or rub the area to comfort it.

It’s important to realize, however, that not all inputs stimulate motor “actions” or outputs, like grabbing an area after a pinch. The nervous system is responsible for communicating messages throughout the body 24/7, many of which without conscious thought.

For example, the stomach has sensors that detect when we eat, and those nerves tell the body to break down food and release chemical molecules to be used for energy. In this process, some of those changes also tell us to stop eating; chemical messengers (neurotransmitters) will let you know that you’re no longer hungry. In other words, the nervous system may be responsible for telling you about your appetite.

How does this relate to the ECS? Think receptors. Environmental changes in the stomach stimulates chemical changes (think neurotransmitters, proteins, enzymes, etc.) to keep the body systems functioning as they should. For those chemical molecules to do their job, they need places to land (aka receptors). And what have we already learned? The ECS has millions of receptors throughout the body.

ECS receptors CB1 and CB2 can be found in the gastrointestinal system linings, helping to mediate everyday functions like appetite and digestion. Animal researchers introduced the theory that the active CB1 receptors may mediate hedonic value of food, meaning the desire to eat and the pleasure we get from it (even if chemical changes tell us we’re not hungry). This has not been proven in humans, but such information may be beneficial in the treatment of pathologies like cancer or AIDS that decrease one’s appetite or pleasure reward system.

Now that we understand basic interactions between our ECS receptors and endocannabinoids in relation to nervous system inputs/outputs we can question the bigger picture of the ECS. If it’s located in every body system of ours, it must have a role in each of those systems, right? Next, we can consider the ECS and its effects on the musculoskeletal system. How might it affect major things like motor control, bone strength, pain and stiffness?

Check back for the release of our next article in a series about the ECS and different biological systems, or sign up on our website and be notified about news and other updates!

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