We know that the brain is the main element responsible for controlling and managing the set of processes carried out in our body. But the truth is that the rest of the systems are also of great importance for its maintenance and have the potential to influence its activity.
An example of this is the digestive system, thanks to which we can obtain the necessary nutrients to stay alive. Brain and stomach are related and communicate through nerve impulses and the transmission of chemical substances.
Functional divisions of the nervous system
When we talk about the nervous system we generally divide it into the central nervous system, in which we mainly find the brain and spinal cord and peripheral or autonomic nervous system, which would correspond to the set of ganglia and nerves that innervate the different organs and cause information from the organs to pass to the brain and vice versa.
Within the autonomic nervous system, we usually identify two basic subsystems, the sympathetic and the parasympathetic which are responsible for managing the set of activities that the body carries out outside our consciousness and preparing our body to face dangerous situations (or reducing activation once said situation has passed).
However, There is a third subsystem of the autonomic nervous system, little studied and often ignored despite its tremendous importance for survival. This is the enteric nervous system, a part of our bodies related to the fascinating phenomenon of dialogue between the viscera and the brain.
The enteric nervous system
The enteric nervous system is of capital importance in the survival of the organism. It is the set of nerve fibers that innervate and control the functioning of the digestive system It controls aspects such as the movement of the muscles of the digestive tract that allow food to reach the stomach, the secretion of acids and enzymes that dissolve food, the absorption of nutrients and the expulsion of waste.
This system It is made up of millions of neurons (in an amount similar to that of the spinal cord) distributed throughout the digestive tract and although it is influenced by the sympathetic and parasympathetic systems, it is controlled by the enteric ganglia in a partially independent manner, acting reflexively. It is not for nothing that the digestive system has sometimes been called the second brain.
In this system also a large amount of hormones and neurotransmitters can be found (particles that act as messengers between neurons), such as serotonin (of which most of what we present in our body is found and synthesized in this system, although it is also produced by the brain), dopamine, substance P or GABA among many others.
These neurotransmitters are regulated by the enteric system itself, although there is an influence on this system by those of the central system.
Stomach-brain nervous communication
Although it has some independence, the enteric system and the central nervous system are linked and some nerves of the central nervous system connect with different organs of the digestive tract.
The vagus nerve is the main means of nervous communication between brain and digestive system. This nerve has great importance in different body systems; In the case of the stomach, it has been found that a bidirectional communication is established in which in fact the amount of information that goes from stomach to brain is greater than that from brain to stomach.
That there is a greater transmission of information from the stomach to the brain than vice versa is due to the need to control intake The behavior of eating is governed by the brain, which causes the need for the brain to receive information about the good or bad functioning of the digestive system or whether the consumption is harmful or beneficial, as well as whether the level of consumption is being excessive (feelings of satiety and hunger).
Despite this, the lazy helps control intestinal activity especially when the body is in a situation of tension or danger. In this situation, the sympathetic system contributes to stopping the functioning of the digestive system. When the dangerous situation passes, it is the vagus nerve that is mainly responsible for reactivating its functioning by acting at a parasympathetic level. It also participates in the emission of bile.
Furthermore, while the enteric system is capable of synthesizing and managing neurotransmitters, it is also affected by brain function. Situations that generate stress or anxiety affect the enteric nervous system and their motility, as well as neurochemical imbalances such as those that occur during depression. Some of the hormones involved in this brain-digestive tract relationship are serotonin, norepinephrine and dopamine. Also acetylcholine, which is important, for example, in the functioning of the vagus nerve.
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The role of intestinal flora in communication
In addition to the role of nerve conduction and neurotransmitters, the intestinal flora also has an effect in the communication between the enteric nervous system and the central nervous system.
The microorganisms that populate our digestive tract have an influence on whether the enteric system reports the good or bad state of the system to the brain, through the modification of the secretion of neurotransmitters. In addition, affects the functioning of the immune system which in turn generates an indirect effect on behavior and health status.
Various research with rodents also reflects that the functioning of the digestive system and the intestinal flora and fauna They may even have an effect on behavior through variations in the structure and functioning of the brain, altering responses to certain neurotransmitters.
Effects of communication between the brain and the digestive system
The fact that the brain and digestive system are connected is of great importance and has very relevant implications. And there is an influence by the digestive system on brain functioning, and vice versa.
The presence of intestinal disorders may be linked to aspects such as anxiety and it has been shown that the presence of anxious or depressive disorders can cause the worsening or even the appearance of digestive problems such as peptic ulcer or irritable bowel syndrome.
It has even been detected that some of the microorganisms that line our digestive system can generate antioxidant and anti-inflammatory substances that can positively affect our brain, stimulating protective cells called astrocytes and potentially delaying neurodegeneration. This may make it interesting to carry out further research on these effects.
But even today it is common that among the various guidelines recommended for some mental disorders there are mentions of dietary and nutritional aspects such as less consumption of certain substances or following diets specific (for example by increasing the level of tryptophan consumed, which in turn is related to the secretion of neurotransmitters).