What neutralizes acidic chyme in the duodenum?

The neutralization of acidic chyme in the duodenum occurs primarily through the mixing of bicarbonate and fluids. When chyme, which is highly acidic due to gastric secretions, enters the duodenum from the stomach, it needs to be neutralized to provide an optimal pH for enzymatic activity in the small intestine. The pancreas secretes bicarbonate into the duodenum, which is a basic compound that effectively raises the pH of the chyme. This neutralization is critical not only for enzyme functioning but also to protect the intestinal lining from damage caused by acidity.

While alkaline intestinal enzymes do play a role in the digestive process, their activity depends on the neutralization of acid first. Without sufficient bicarbonate to raise the pH, these enzymes would not function efficiently, highlighting the essential role of bicarbonate in this process. Other options, such as mixing with sodium and potassium or bile, do not specifically address the neutralizing action on acidic chyme and thus are not the primary means of achieving the necessary pH balance in the duodenum.