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How the Digestive System Works

Tap an organ to see its role in digestion.

Mouth

Digestion begins here, where chewing physically breaks down food and saliva starts the chemical breakdown of starches using an enzyme called amylase.

Esophagus

A muscular tube that uses wave-like contractions (peristalsis) to move swallowed food from the throat down to the stomach.

Stomach

A muscular sac that churns food while mixing it with acid and digestive enzymes, breaking it down into a semi-liquid mixture called chyme.

Small Intestine

The primary site of nutrient absorption, where most of the breakdown of food into usable nutrients is completed and absorbed into the bloodstream through millions of tiny finger-like projections called villi.

Large Intestine

Absorbs remaining water and electrolytes from undigested food material, and is home to trillions of beneficial bacteria that further break down remaining matter before it becomes waste.

Liver and Pancreas

Though not part of the direct digestive pathway, the liver produces bile that helps break down fats, and the pancreas produces enzymes and bicarbonate essential for digesting food in the small intestine.

A journey that can take over a day

This page is for general educational information only and is not a substitute for professional medical advice. Food typically takes anywhere from 24 to 72 hours to travel through the entire digestive system, from the moment it enters the mouth to the moment waste is eliminated, with most of that time spent in the large intestine.

Frequently Asked Questions

Why does the stomach not digest itself with its own acid?

The stomach lining is protected by a thick layer of mucus that shields the underlying tissue from the highly acidic digestive juices, though this protective barrier can sometimes break down, contributing to conditions like ulcers.

What is the difference between the small and large intestine?

Despite its name, the small intestine is actually longer but narrower in diameter, and is primarily responsible for nutrient absorption, while the large intestine is shorter but wider, and is primarily responsible for absorbing water and forming waste.