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Name: Mansi P.
Status: student
Age: 17
Location: N/A
Country: N/A
Date: 3/22/2004
Question:
when food enters the stomach, it stimulates the production and secretion of hydrochloric acid for digestion, reducing the pH of the stomach contents from 4 to 2.. can u tell me the concentration before and after the change in pH. and also how the stomach protects itself from the corrosive effects of this low pH level. ...

Replies:
pH is a direct measure of the acidity (i.e. H(+) concentration). The definition is pH= -log(H+) where the log is the common base 10 log. So a pH = 4 means the H(+) = 10^-4 and pH = 2 means the (H+) is 10^-2 or a 100-fold increase in the (H+) concentration. The cells that line the stomach are resistant to high acid concentration (assuming they are intact and healthy). In addition, cells lining the stomach secrete mucous that also offers protection. Surprisingly, the cells in the esophogus and small intestine are very sensitive to high acid concentrations, giving rise to duodenal ulcers and acid reflux.

Vince Calder


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