Bicarbonate & Chloride Ions: Neutralizing Chyme for Optimal Digestion

The correct answer is bicarbonate ions (HCO3-) and chloride ions (Cl-).

Chyme is the partially digested food that leaves the stomach and enters the small intestine. It is acidic due to the presence of hydrochloric acid from the stomach. To neutralize the chyme and create an alkaline environment suitable for the action of pancreatic enzymes, the pancreas secretes bicarbonate ions (HCO3-) into the small intestine. These ions react with hydrogen ions (H+) from the chyme to form carbonic acid (H2CO3), which then dissociates into water (H2O) and carbon dioxide (CO2). The chloride ions (Cl-) help to maintain the electrical balance in the small intestine.