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Bicarbonate and phosphate ions buffer saliva. What pH range do they hold it at?
AA pH between 1.5 and 3.5
BA pH between 7.1 and 8.2
CA pH between 7.6 and 8.6
DA pH between 6.35 and 6.85
Answer & Solution
Correct answer: D. A pH between 6.35 and 6.85
1. Saliva is about 95.5 percent water, with ions, enzymes and other substances in the rest.
2. Bicarbonate and phosphate ions act as chemical buffers within that mixture.
3. They hold saliva at a pH between 6.35 and 6.85, which is just on the acidic side of neutral.
4. A pH of 1.5 to 3.5 is the strongly acidic range of stomach contents.
5. The ranges 7.1 to 8.2 and 7.6 to 8.6 belong to pancreatic juice and bile, both alkaline.
_Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 23 "The Digestive System", section 23.3 The Mouth, Pharynx, and Esophagus_
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