What body systems are involved in the gut-brain connection?
What healthcare providers refer to as the gut-brain axis is the network of nerves that connect your brain and gut and send signals back and forth. But your nervous system also works closely with your endocrine system, which produces hormones that communicate things like hunger, fullness and stress. And it works closely with your immune system to respond appropriately to injury or disease in your gut.
Within this network, some of the key players in the gut-brain connection include:
Enteric Nervous System
Your enteric nervous system is the neural network that operates within your gastrointestinal (GI) tract and controls its digestive functions. With more than 500 million neurons, it’s the most complex neural network outside of your brain. It’s also unique in that it can operate somewhat independently from your brain and central nervous system. This has led some scientists to refer to it as a “second brain”.
Your enteric nervous system is a special division of your autonomic nervous system, which governs the automatic functions of your internal organs. It operates as part of your overall autonomic nervous system, but also on its own. It can gather information about the conditions inside your GI tract, process that information locally and generate a response without sending it back to your brain.
Vagus Nerve
Your vagus nerve is the main link between your enteric nervous system and your brain. It’s one of your 12 cranial nerves, which begin in your cranium and travel down through your body, branching out along the way. Your vagus nerve conveys sensory information about the conditions inside your gut from your enteric nervous system to your brain. In response, it conveys motor signals from your brain to your gut.
The vagus nerve mediates various reflexes that operate within your gut in response to changing conditions, like chemical changes or the presence of food. These are called vagal reflexes. Intrinsic vagal reflexes operate within your enteric nervous system without involving your brain. Extrinsic reflexes operate through communication between your enteric nervous system and central nervous system.
Gut Microbiome
Believe it or not, the bacteria that live in your gut are also involved in your gut-brain connection. Gut microbes produce or help produce many of the chemical neurotransmitters that convey messages between your gut and brain. They also produce other chemicals that can affect your brain through your bloodstream. Your brain and gut, in turn, can affect your gut microbiome by altering its environment.
Recent studies have shown that the gut microbiome may be involved in various neurological, mental health and functional gastrointestinal disorders. Functional disorders are those that cause persistent symptoms but don’t have any obvious physical cause. There’s a significant overlap among people who have functional gastrointestinal disorders, like IBS (irritable bowel syndrome), and who have mental health disorders, like anxiety.
link