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Did you know your gut has a brain of its own? It’s called the enteric nervous system. The brain in your gut is embedded in the wall of the digestive tract. Together with your “big brain,” the enteric nervous system helps control gastrointestinal function, including the mixing and grinding of food in the stomach and absorption of nutrients in the intestines.

An adult’s enteric nervous system is made up of 200 to 600 million nerve cells (neurons). That’s as many neurons as are in a cat’s brain or even your spinal cord! The neurons in the enteric nervous system interact with smooth muscle to move food through the digestive system. The brain in your gut also plays an important role in regulating your immune system. It attacks bacteria and viruses (pathogens) that invade the digestive tract by releasing protective substances called peptides that make it harder for pathogens to do harm.

Although the brain in your gut functions independently from the “big brain”—and is the only organ in your body that can do so—normal digestive function requires communication between the enteric nervous system and the brain. The enteric nervous system provides sensory information to the brain to help you decide what, when and how much you eat. When you’re hungry or see something you’re craving (like a piece of chocolate cake or a juicy burger), your brain tells your gut to start the digestion process by producing gastric secretions in the stomach.

Problems with the enteric nervous system can lead to different digestive diseases such as irritable bowel syndrome and functional constipation. Studies have demonstrated that losing some of the neurons in the gut can be a cause of these conditions. Understanding how and why these neurons die is an important topic of research that could result in finding new treatments for digestive diseases.

To learn more about digestive disease, visit the National Institute of Diabetes and Digestive and Kidney Diseases website.

Ninotchska Delvalle is a doctoral candidate in the neuroscience program at Michigan State University. Her research focuses on how specialized cells of the enteric nervous system (enteric glia) contribute to the development of gastrointestinal disease.