Curiosity 6 of 10
6. The stomach replaces its own lining every few days
The stomach acid is very acidic, but the organ does not digest itself. It protects itself with a layer of mucus and renews the cells of the inner lining every few days.
Acid inside, protected at the wall
Gastric juice contains hydrochloric acid, and the pH inside the stomach usually stays between 1.5 and 3.5, an acidity similar to lemon juice or even stronger. This environment helps break down food proteins and kills much of the microbes that come in with the food.
To avoid being attacked, the stomach wall is covered by a thick layer of mucus, containing bicarbonate, which neutralizes the acid right next to the cells. It is a barrier the body produces nonstop.
Even so, the surface cells wear down. They are replaced all the time, and the inner lining renews itself in a few days. When this protection fails, wounds can form in the wall, called ulcers.
The discovery that a bacterium, Helicobacter pylori, is behind many ulcers earned the 2005 Nobel Prize in Physiology or Medicine for Australians Barry Marshall and Robin Warren. Before that, stress was believed to be the main cause.
When empty, the stomach is small, but it stretches a lot. The folds of the inner wall open as it fills, and an adult receives, in an ordinary meal, between 1 and 1.5 liters, and it can stretch well beyond that.
Did you know? To prove the idea, Barry Marshall even drank a culture of the bacterium in 1984. He developed inflammation in the stomach, which he later treated with antibiotics.
