|MadSci Network: Chemistry|
The pH of the stomach may go as low as 1.0. This is a very acidic level. Because the pH scale is a logarithmic scale, the pH of the stomach is hundreds or thousands or millions of times stronger than typical cellular fluids which are generally close to 7.0 (the neutral level on the pH scale.) When food comes into the stomach, the pH may rise to levels in the 3.0 to 4.0 level due to the buffering capacity of proteins. The stomach secretes hydrochloric acid (HCl). This strong acid can directly degrade proteins and it also creates conditions in the stomach that encourage the formation of the ionic form of iron that can be absorbed. The enzymes that the stomach lining secretes are specially "designed" so that they work best in a strongly acid solution. Sometimes the protective ability of the stomach lining breaks down and the acid eats a hole into the stomach or duodenum. These are gastric or duodenal ulcers, respectively. They are treated with drugs that inhibit the stomach's production of acid. After the food enters the duodenum, bicarbonate ions are secreted to neutralize and alkalinize the food mixture. The pH of the small intestine is in the 8.0 area. Solutions at a pH of 1.0 are strong enough to burn through fabrics, injure eyes or irritate skin. Be careful if you are trying to replicate stomach conditions. Wear eye protection and wash your hands if you come into contact with the solutions. Have a plan for eye irrigation and transport to an emergency room if an accident occurs. Hope this helps, David Winsemius, MD
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