Lost In Translation - The Gut-Brain Axis Malfunction Part 2
Ever heard the term 'second-brain', or that 95% of the bodies feel good hormone serotonin is produced in the gut?
This second brain term is referring to the enteric-nervous system (ENS) of the gut, the ENS is a collection of nerves interplaying with microbiota to communicate with our autonomic nervous system (ANS). Need a little refesher of the ANS? I have briefly laid out the opposing systems for you below.
The Three Branches of the Nervous System
The central nervous system is comprised of the brain and spinal cord as well as the autonomic nervous system (ANS). The ANS is responsible for many of the subconscious actions our nervous system performs, such as regulating organ functioning and the activation of the sympathetic (SNS - fight or flight response) or parasympathetic (PNS - rest and digest response) nervous system. The ANS also exerts control over the enteric nervous system (ENS) to control the smooth muscle of the organs as well as glandular functions.
Sympathetic Nervous System | Parasympathetic Nervous System |
Controls the functions of body during perceived threat | Controls the functions of the body at rest |
Fight or Flight Response | Rest and Digest Response |
Increases Heart Rate Dilates Bronchial Tubes Muscles Contract Decreases Gut Motility Decreases Stomach Secretions Diverts Blood to Muscles & Extremeities | Decreases Heart Rate Constricts Bronchial Tubes Muscles Constrict Increases Gut Motility Increases Stomach Secretions Returns Blood to Core & Organs |
Sympathetic Nervous System
The SNS is responsible for regulating key functions required for survival, for example, imagine being in a situation where you need to make a snap decision, but instead you thoughtfully consider each option before deciding and then act - in this time you could have been seriously harmed! To put it simply the sympathetic system is essentially responsible for turning perception into immediate physiological action, thus having an action on many organs within the body.
Parasympathetic Nervous System
The PNS on the other hand is responsible for the functions of the body necessary for the restoration of the body - digestion, relationships, and relaxation. If we are continually operating in a sympathetic response we are lacking the ability to fully digest our foods due to lack of digestive secretions, are unable to relax and connect with friends due to high circulating stress hormones, and cannot heal damaged tissues because blood flow is being diverted away from key organs. We need to be able to enter into the parasympathetic response in order to get the most enjoyment out of life!
Enteric Nervous System
Whereas the SNS and PNS response are for the most part exclusive, meaning they work in opposition to eachother, the ENS can function to a degree in either state but is effective when in the rest and digest state. The ENS is the final arm in the central nervous system. The enteric nervous system is the main way in which the central nervous system can act to influence gut processes, and this conglomeration of nerves and actions is massive! The ENS has as many neurons as the spinal cord and produces more than 30 neurotransmitters within the body! The key functions that the enteric nervous system regulates are motility, ion transportation across the gut lumen, and gastrointestinal blood flow.
Now that we know the different branches of the nervous system and their vast actions within the body. Let's find out how to affect them for better health! Enter the vagus nerve...
Vagus Nerve - The Nervous System's Rosetta Stone
The vagal nerve is the tenth cranial nerve and the longest nerve in the body extending from the brainstem to the abdomen.The vagus nerve is the main communication pathway relaying information of the physiological health of the organs to the brain, and it sends information from the brain down!
The vagus nerve is paramount for communication between the gut and brain. When the vagus nerve is stimulated, it activates the parasympathetic response, this allows your body to drop into rest and digest mode - essential for healing, inflammation management and mental wellness!
One way that the vagus nerve influences mental wellness is by improving resilience to stressful events. This is done through triggering the PNS response quicker, and stronger, stopping the negative effects of the stressful event (such as elevated cortisol) and preventing further harm from rampant inflammation.
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