A human body is an exceptional and unique system, perfectly balanced, resistant to numerous factors that can potentially harm it, and able to recover and regenerate itself even if we have been seriously injured. But the most important and, so far, the most valuable part of it responsible for our organism’s general functioning and cognitive processes is, of course, the brain. Or, as it turns out, a brain, as there is more than one we have. Hardly any people haven’t experience something that is often referred to as ‘gut feeling’ or ‘butterflies’ in their stomach. As a matter of fact, these are completely real reactions happening in our body, and the reason they exist is our enteric nervous system, also called by scientists ‘the second brain’. Enteric nervous system, previously considered to be just a collection of relay ganglia, is actually a complex and extensive network of about 100 million neurons located all over our guts, what is more than we have in our spinal cord or peripheral nervous system . This network is filled with highly perceptional neurotransmitters that not only control our digestive process literally from esophagus to anus, but also carry information from the gut to the brain (though not the other way around, making it pretty independent). As Emeran Mayer, professor of physiology, psychiatry and biobehavioral sciences at the David Geffen School of Medicine at the University of California, Los Angeles (U.C.L.A.) has told Scientific American, “A big part of our emotions are probably influenced by the nerves in our gut”. Therefore, the enteric nervous system is now recognized by leading neuroscientists as a ‘brain in its own right’. Michael Gershon, chairman of the Department of Anatomy and Cell Biology at New York–Presbyterian Hospital/Columbia University Medical Center, an expert in neurogastroenterology and author of the 1998 book The Second Brain states that one of the reasons we experience gut feeling lies in the fact that neurons in the gut play significant part in our physiological reaction to stress. Thus, our daily emotional state may be dependent on the signals from the enteric nervous system to the ‘main’ brain. Due to this factor, as scientist also says, electrical stimulation of our vagus nerve works in depression treatment. Also, our enteric nervous system provides us with optimal amount of energy and necessary nutrients by sending requests for certain types of food to our brain. Consequently, it has played a big part in our survival as a species end ensured our evolution. At the same time, it is responsible for production of 95% of serotonin and 50% of dopamine, creating a strong connection between what we put in our stomach and how good our mental health is. Moreover, bacteria living in the gut, if the environment is properly balanced, are responsible for keeping healthy weight, impacts state of our skin and minimizes probability of gastrotestinal and eating disorders. So, enteric nervous system is indeed an astonishing thins that means a lot to our general life quality, both physical and mental. This video, prepared by the team of ASAP Science, presents a detailed analysis of its work.