Linda has heard that the acidic environment of the stomach is similar to that of a car battery. if the stomach is so acidic, why doesn't the acid eat away at the stomach lining and cause holes in the stomach? the stomach contracts during peristalsis, which pushes the acid out of the stomach and protects it. the stomach produces bacteria, which denature the acid in the stomach and protect it. the stomach is lined with a layer of mucus that protects it. the stomach produces bicarbonate, which neutralizes the acid in the stomach and protects it.