A full stomach stretches to hold a meal and then slowly returns to size.

The longer version

The stomach wall is built from layers of smooth muscle arranged in different directions, which lets it expand in more than one plane. Its inner lining is thrown into folds that flatten out as volume increases, so capacity grows without the wall becoming taut.

Stretch sensors in the wall send signals to the brain, and that feedback contributes to the feeling of fullness after a meal. Once the contents have been churned and released into the small intestine, the muscle tone returns and the organ narrows again. Capacity varies noticeably between people, and the wall adapts over time to habitual portion sizes.

Where this entry sits

These facts look at how the human body works in ordinary moments, from breathing and blinking to balance and sleep. They focus on anatomy, senses, and small reactions that happen constantly without any conscious effort. The full list sits on the Human Body page, where every entry is listed in order.