5 Fascinating Facts About Your Digestive System

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  • The last few years have seen big strides in what we know about the digestive system. Simply put, your digestive system is a complex collection of organs that work together to convert food you eat into energy and nutrients your body can use. But it’s not just about what goes in your body and what comes out. Your digestive system affects every aspect of your health, from your emotional well-being to the strength of your immune system.

  • 1
    Within your gut lies a whole universe.
    Woman holding lower abdomen

    Inside your digestive system live trillions of bacteria; in fact, there are 10 times more bacteria living in your gut than all other cells in your entire body! Along with these bacteria are viruses and fungi, and together, they’re called microbiota. They make up what’s known as the microbiome. These microbiota play a role in developing your immune system after you’re born, and continue to help you stay healthy throughout your life, among many other functions.

  • 2
    Your digestive system is known as your “second brain.”
    middle age male touching stomach

    Experts have recently determined there’s a strong connection between your gut and your mental health, and it goes beyond feeling “butterflies in your stomach” or getting a “gut feeling.” It turns out microbiota in your gut are constantly communicating with your brain, influencing your emotional behavior, stress response, and even your perception of pain. Research shows that changing the microbiota in your gut can impact your mental health directly. For example, known side effects of antibiotics (which kill some bacteria in your microbiome) are anxiety and depression. And studies have found patients with depression have specific bacteria in their microbiomes that people without depression lack.

  • 3
    Your digestive system is made up of hollow and solid organs.
    Human digestive system, artwork

    Your digestive system is made up of your gastrointestinal (GI) tract and your liver, pancreas and gallbladder. When we refer to the GI tract, we’re talking about the long path your food takes from your mouth to your anus. That path consists of hollow organs—your mouth, esophagus, stomach, small intestine, large intestine, and anus—through which food travels. But there’s also a few solid organs in the mix: your liver, pancreas, and gallbladder. These organs release different juices that help break down your food and enable your body to absorb nutrients and fats.

  • 4
    Your GI tract doesn’t need gravity to move food along.
    woman eating salad

    When food enters your mouth, the walls of your GI tract use a special layer of muscles to move, guiding your meal through your system. This process is called peristalsis, and it’s the reason you can digest food while hanging upside down or living in space. Peristalsis causes the GI tract to contract and relax—movement that can look like an ocean wave crashing and receding through your digestive system.

  • 5
    Your small intestine is actually longer than your large intestine.
    female nurse holding anatomical model of human colon with pathology

    Your intestines are long tubes that food moves through when traveling from your stomach to your anus. In your body, your intestines are folded up in many layers, but stretched out, they’re quite lengthy. Your small intestine is about 1 inch in diameter, but if you unrolled it, it’d measure about 22 feet long. Your large intestine, also known as your colon, is about 4 inches in diameter, but it’s much shorter in length than its counterpart—just 6 feet long.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2019 May 22
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
  1. The Brain-Gut Connection. Johns Hopkins Medicine. http://www.hopkinsmedicine.org/health/healthy_aging/healthy_body/the-brain-gut-connection
  2. The gut-brain connection. Harvard Health Publications. http://www.health.harvard.edu/diseases-and-conditions/the-gut-brain-connection
  3. Quigley EM. Gut Bacteria in Health and Disease. Gastroenterology and Hepatology. 2013; 9(9): 560-569. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3983973/
  4. Rogers GB, Keating DJ, Young RL, et al. From  gut dysbiosis to altered brain function and mental illness: mechanisms and pathways. Molecular Psychiatry. 2016;21: 738-748. http://www.nature.com/mp/journal/v21/n6/full/mp201650a.html
  5. The Digestive System & How It Works. National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/digestive-diseases/digestive-system-how-it-works
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