The human body is designed to function within a very narrow pH. Your body's pH is a measurement of the amount of hydrogen ions in your blood, which affect the acidity level. Enzymes are protein catalysts that improve the rate at which chemical reactions take place. The digestive enzymes in your GI tract function at an optimal pH, which is determined in part by the secretion of hydrochloric acid by your stomach.
PH Levels
Your pH level is a measurement of the acidity of your tissues. The pH scale goes from 0 to 14. The greater the number, the more hydrogen ions are present and the more acidic the environment. On this scale, seven is considered neutral. The pH of your blood is roughly 7.4, which is slightly alkaline, or basic. Other parts of your body have different pH values.
Stomach PH
Your stomach has the lowest pH of any part of your body. In other words, your stomach is very acidic. The parietal cells of your stomach secrete HCl, or hydrochloric acid, which acidifies the gastric contents to between pH 1 and 2, according to the textbook "Physiology." The function of this low pH is to convert the inactive enzyme pepsinogen to its active form, pepsin. Pepsin is a protease, or protein-digesting enzyme, that begins the process of breaking down dietary protein into amino acids your body can absorb.
Small Intestine
As your stomach contents hit your small intestine, other enzymes continue the work of digestion. The source of these enzymes is your pancreas, as well as the lining of your small intestine. Amylase and fat-digesting enzymes called lipases break down dietary carbohydrates and lipids, respectively, into smaller molecules that enter your bloodstream for use as fuel. However, these enzymes require a less acidic environment to function properly; they rely on the pancreas to secrete bicarbonate, which neutralizes the stomach's hydrochloric acid and increases the pH, according to Richard Harvey, Ph.D., author of the textbook, "Biochemistry."
Considerations
Many factors stimulate the stomach to secrete hydrochloric acid. In fact, smelling and tasting food promote stomach acid secretion. Distension of the stomach, as occurs after a big meal, also releases stomach acid, as do high protein foods such as beef and fish. Your stomach produces mucus to protect itself against the corrosive effects of acid. However, too much acid can damage the lining of your stomach, creating ulcerative lesions. This condition is known as peptic ulcer disease and may require treatment with medications.
References
- "Physiology"; Linda S. Constanzo; 2010.
- "Biochemistry"; Richard A. Harvey, Ph.D.; 2010
