How does stomach acid not affect your stomach itself, and how does it stay in your stomach?
In: Biology
The skin of your stomach is made from three layers: The mucosa, the submucosa and a muscle layer.
The mucosa is the inner-most layer that has a lot of cells, glands and pits. There are a handful of different types of cells, including the parietal cells and the foveolar cells.
The parietal cells produce the stomach acid, hydrochloric acid, which is highly acidic (pH around 1-3) to destroy bacteria and begin first steps of the digestion process. These cells usually sit in little ‘pits’ in the mucosa and will excrete the acid out into the stomach.
The foveolar cells are sitting on the top of the mucosa layer. They constantly produce a layer of mucus to cover the membrane or stomach lining. Because the mucus is alkaline, it is on the opposite end of the pH spectrum compared to the stomach acid. It is also a very thick, viscuous fluid.
Because of those differences in pH and viscosity between the acid and the mucus protecting the stomach lining, the stomach acid can be released into the stomach from the mucosa without being able to touch the mucosa once it’s inside the stomach. At the same time your body strictly observes the pH in your stomach and the balance of mucus/acid that is produced at all times.
When this mechanism is disturbed, your stomach acid can cause damage from the inside. This is a common cause for stomach ulcers for example, and also one of the reasons why people with GERD (acid coming up the esophagus) have trouble with chronic inflammation.
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