= 800 nmol/L). After multiplying the constants (800 × 0.03 = 24) and solving for HCO, the equation is simplified to: In other tissues The bicarbonate buffer system plays a vital role in other tissues as well. In the human stomach and duodenum, the bicarbonate buffer system serves to both neutralize gastric acid and stabilize the intracellular pH of epithelial cells via the secretion of bicarbonate ion into the gastric mucosa. In patients with duodenal ulcers, Helicobacter pylori eradication can restore mucosal bicarbonate secretion and reduce the risk of ulcer recurrence. Tear buffering The tears are unique among body fluids in that they are exposed to the environment. Much like other body fluids, tear fluid is kept in a tight pH range using the bicarbonate buffer system. The pH of tears shift throughout a waking day, rising "about 0.013 pH units/hour" until a prolonged closed-eye period causes the pH to fall again. Most healthy individuals have tear pH in the range of 7.0 to 7.7, where bicarbonate buffering is the most significant, but proteins and other buffering components are also present that are active outside of this pH range. References External links Electrolyte disturbances Buffer solutions