The enteric nervous system and its physiology

Did you know that our brain is closely linked to the intestine thanks to enteric nervous system? The enteric nervous system, together with the sympathetic and parasympathetic nervous systems, make up the autonomic nervous system. The size and complexity of the enteric nervous system is immense and contains as many neurons as the spinal cord.

The main components of the enteric nervous system are two networks or plexuses of neurons, the myenteric plexus and the submucosal. In this Psychology-Online article we explain the enteric nervous system and emotions.

Index

1. What is the enteric nervous system: the second brain
2. Physiology and components of the enteric nervous system
3. Relationship between emotions and the enteric nervous system

The nervous system exerts a profound influence on all digestive processes, such as motility, ion transport associated with secretion and absorption, and gastrointestinal blood flow. Part of this control is produced by the connections between the digestive system and the nervous system central, but also the digestive system is endowed with its own local nervous system called the nervous system enteric.

The "gut-brain connection", also known as the "gut-brain relationship," may sound very strange, but it is not. In fact, most of us refer to this (concept) without knowing it. For example, when you are under stress, do you eat more than normal or experience signs of indigestion?

How does the enteric nervous system work?

Sometimes when we are stressed we experience gastric cramps as well as intestinal cramps. This is because our gastrointestinal tract is innervated with many nerves (specifically 200-600 million neurons), which run from the esophagus to the anus. This system is called the enteric nervous system and is the reason why our gut is often referred to as the second brain.

This second brain is sensitive to the emotions that threaten our life, that is, to the fight or flight response and the signals they pick up will be sent to the other nervous network of our intestine, the central nervous system, to execute a response, such as the activation of the defecation centers (which results in going to the bathroom more times) or the alteration of gastric juice production through signals sent to the stomach.

In addition to reacting to our emotions, we need this enteric nervous system as it ensures good blood flow to the intestine and proper digestion of food.

Image: calinalcacer.com

The enteric nervous system consists mainly of two plexuses, which are embedded in the wall of the digestive tract and extend from the esophagus to the anus:

• The myenteric plexus it is situated between the longitudinal and circular layers of the tunica muscle and, appropriately, exerts control over the motility of the digestive tract.
• The submucosal plexus, which as its name suggests, is buried in the submucosa. Its main function is to detect the environment within the lumen, regulate gastrointestinal blood flow, and control epithelial cell function. In regions where these functions are minimal, such as the esophagus, the submucosal plexus is sparse and may be missing in sections.

In addition to the two major enteric nerve plexuses, there are minor plexuses below the serosa, within the circular smooth muscle, and in the mucosa.

Within the enteric plexuses There are three types of neurons, most of which are multipolar:

• Sensory neurons they receive information from sensory receptors in the mucosa and muscle. At least five different sensory receptors have been identified in the mucosa, which respond to mechanical, thermal, osmotic, and chemical stimuli. Acid, glucose and amino acid sensitive chemoreceptors have been shown to essentially allow light content to be "tasted". Sensory receptors in muscle respond to stretch and tension. Collectively, enteric sensory neurons collect a comprehensive battery of information about intestinal contents and the state of the gastrointestinal wall.
• Motor neurons within the enteric plexus they control gastrointestinal motility and secretion, and possibly absorption. In performing these functions, motor neurons act directly on a large number of effector cells, including muscle. smooth, secretory cells (main, parietal, mucous, enterocytic, pancreatic exocrine) and endocrine cells gastrointestinal
• Internal neurons are largely responsible for integrating information from sensory neurons and providing it to enteric motor neurons ("programmers")

Another lifestyle example to illustrate this gut-brain relationship would be the role of serotonin and how serotonin levels in our body can affect our mood and sleep. Serotonin is a neurotransmitter produced by our brain and gastrointestinal tract, the latter being the major producer of serotonin. The relationship between neurotransmitters and emotions it is very close, so in this case we can observe a direct relationship between emotions and the enteric nervous system.

About the 80-90% of serotonin of our body is produced in our gastrointestinal tract.

Have been found low serotonin levels in people with depression, and it's no wonder serotonin has been called the "feel-good hormone." In addition, our brain uses serotonin to produce melatonin, a fundamental hormone to help us sleep. Therefore, the amount of serotonin that your body produces would have a direct impact on the quality and quantity of your sleep.

The gut microbiome and our emotional and mental health

Not many people know this, but our gut bacteria population has an impact on our emotional and mental health, as well as our ability to sleep at night. A study involving 40 healthy women found that women with a higher percentage of the Prevotella species of bacteria in their stools were more likely to experience negative emotions after negative images were shown compared to those women in whom the highest percentage of the Bacteroides species of bacteria in their feces.

Likewise, individuals with autism appear to be more susceptible to gastrointestinal problems such as inflammatory bowel disease and leaky gut, and this could be due to the alteration of the microbial composition of the gut. However, when this group of individuals were given a certain probiotic strain, this resulted in an improvement in the integrity of the intestinal barrier, as well as a reduction in behaviors characteristically related to autism.

Finally, there is a close relationship between our gut bacteria and sleep. Bacteria in our gut help in the production of serotonin (which then goes on to form melatonin), but did you know? you that our gut microbial population can be affected by poor sleep or poor sleep quality? This means there is a vicious cycle of sleep deprivation, poor sleep quality, and poor gut health. If you want to know more information about these curious data, you can consult the MetaHIT project scored by Francisco Guarner.

This article is merely informative, in Psychology-Online we do not have the power to make a diagnosis or recommend a treatment. We invite you to go to a psychologist to treat your particular case.

If you want to read more articles similar to The enteric nervous system and its physiology, we recommend that you enter our category of Neuropsychology.

• Quevedo, M. T. THE BRAIN-INTESTINE AXIS AND ITS RELATIONSHIP WITH STRESS.
• Qin, J., Li, R., Raes, J., Arumugam, M., Burgdorf, K. S., Manichanh, C.,... & Mende, D. R. (2010). A human gut microbial gene catalog established by metagenomic sequencing. nature, 464(7285), 59.