How do we know?
↻ One of the pages with a moving picture
An army doctor watched a stomach work, through an opening in a man’s skin.
- In your mouth, teeth chew and saliva begins to break down starches.
- You swallow, and muscles in your esophagus, a tube about 10 inches long, squeeze the food down in waves. This is called peristalsis.
- Your stomach muscles mix the food with acid and digestive juices into a thick soup.
- The small intestine soaks the nutrients into your blood. The large intestine takes in water, and what is left becomes poop.
In 1822 a young man was hurt on Mackinac Island, Michigan, and his wound healed with a permanent opening into his stomach. Army doctor William Beaumont could watch through the opening as the stomach worked.
His experiments, which went on until 1833, helped show that digestion uses both squeezing muscles and chemical juices.
Stretched out, the whole digestive tube of an adult would be about 30 feet long, about 9 meters, folded up inside you.
Wow number
22 feet An adult’s small intestine is about 22 feet long, all neatly folded up inside the belly!
Myth or fact?
Food just falls down to your stomach because of gravity. Myth. Muscles squeeze it along in waves (peristalsis).
Stretched out, the whole digestive tube of an adult would be about 30 feet long. Fact. That is about 9 meters, folded up inside you.
Think about it
Why do you think chewing your food well might help your stomach?
Where in the world?
Mackinac Island, Michigan, USA where, in 1822, a young man was hurt and his wound healed with a permanent opening into his stomach — 45.8492° N, 84.6189° W.
Where these facts come from
Every number on page 72, and who measured it
This page tells us the path food takes, from your mouth to the end.
Digestive System — KidsHealth, a health site for kids from Nemours Children's Health
kidshealth.org/en/kids/digestive-system.html
We checked it on 31 October 2026
This page tells us how long the whole digestive tract is.
What Is the Digestive System? — Cleveland Clinic, a big hospital in Ohio
my.clevelandclinic.org/health/body/7041-digestive-system
We checked it on 31 October 2026
This page tells us how muscles squeeze food along, even against gravity.
Your Digestive System & How it Works - NIDDK — The U.S. National Institute of Diabetes and Digestive and Kidney Diseases
niddk.nih.gov/health-information/digestive-diseases/digestive-system-how-it-works
We checked it on 31 October 2026
This page tells us how Dr. Beaumont studied digestion on Mackinac Island.
Dr. William Beaumont and Alexis St. Martin — Mackinac State Historic Parks in Michigan
mackinacparks.com/blog/dr-william-beaumont-and-alexis-st-martin
We checked it on 31 October 2026
Has this changed?
How food travels through you is not going to change.
What has changed since 1822 is what we can see: doctors now use cameras and scans instead of an opening in the skin.
Words from this page
- esophagus
- The tube that carries food from your mouth to your stomach.
- nutrient
- The useful part of food that your body uses to grow and get energy.
- peristalsis
- Waves of squeezing muscles that push food along.
Try it!
Squeeze a ball along a sock.
1. Put a tennis ball into one leg of an old pair of tights or a long sock. 2. Squeeze the sock just behind the ball with your hands. 3. Keep squeezing, hand over hand, to move the ball to the end.
What happens: the ball moves forward with each squeeze, like food moving through your digestive tube.
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