The Digestive System In A Nutshell- Part Four

Wahoo! You’re in the home stretch here! You have finally made it to part four, the last, in our digestive system series.

You may be wondering what else could possibly be covered. You’re telling me there’s MORE systems at work just to digest some food? Yes I am! Enter… the nervous system!


Along with the endocrine system, the nervous system regulates digestion and acts as a different type of messenger. Using both nerve impulses and neurotransmitters it does everything from direct nervous tissues, smooth muscle contractions to mixing and propelling food stuff and transporting ions.

The digestive system actually possess its own, localized nervous system.. the Enteric System (instead of coming straight down from the CNS). So without further adieu, here is a quick list of the neurotransmitters involved in digestion:


Gaba (gamma aminobutyric)

This fun neurotransmitters is a double agent! It acts as a “downer” on the CNS but a stimulator in the gut. It’s main goal is to stimulate GI movement and help the mucosal wall to function.


stressNow, I’m sure you’ve heard of this guy.. he’s a “fight or flight” hormone that also acts as a neurotransmitter! So he’s a pretty busy one. His responsibility here is to decrease digestive activity.

Thinking logically, this makes sense. When immediate or aggressive action is required, digestion is- and should be- low on the priority scale. The bad news, is that, stress (work, bad relationship etc) is seen as “immediate or aggressive” action. Those stressors, when intense enough, will also release this hormone which results in crappy digestion.


This neurotransmitter promotes muscle contraction as well as cell to cell communication. It aids in digestion by stimulating smooth muscle contractions which helps move food along. It also stimulates the release of many hormones, dilates blood vessels and increases intestinal secretions.

This neurotransmitter is opposite to Norepinephrine as it believes in `rest & digest`.


Released as dietary fat reaches the last section in the small intestine. It then relaxes the LES, blocks the release of stomach acid and regulates contraction and relaxation.

NPY (Neuropeptide)

metabolismPresent in the brain this neurotransmitter stimulates hunger and intake while decreasing the desire to exercise. It also works with other hormones to regulate body composition and metabolism. Typically, it is released when body fat is low or food is scarce

In the digestive system, it slows gastric emptying and transit time. Logically speaking this makes sense, it is released when food is low and digestive efficiency is required.



Another popular neurotransmitter and also a double agent! It is released in both the brain and the enteric system. When released in the brain it tries to adjust anger, temperature, sleep, aggression, appetite. It hits its max 1-2 hours after meals. It acts as an anti depressant and mood regulator.

Serotonin is why people feel more relaxed shortly after eating

In the gut, it is produced within the small intestine. It helps increase the motility of the intestine and reduce the production of acids.

In excessive amounts serotonin can lean to nausea- this is why anti-depressants can cause diarrhea and nausea.

Nitric Oxide & Substance P

Helps with vasodilation within the gut. This helps improve blood flow which aids in nutrient delivery and uptake.

VIP (Vasoactive Intestinal Peptide)

A neurotransmitter with a multitude of uses. It helps inhibit acid release, stimulates the secretion of alkalizing juices, promotes smooth muscle relaxation and vasodilatation. It also stimulates to release of pepsin and the secretion of water and electrolytes.


All in all, the digestive system is a pretty big process. Your body requires only the best of fuel if you expect it to run optimally. More often than not, annoying recurrences (gas, bloating, washroom troubles) can be improved by altering your dietary habits. There is always room for improvements within our diets, if you`d like help with your, contact me for a free consultation.