Final Answer:
The small intestine is protected from the corrosive action of hydrochloric acid in chyme by bicarbonate ions, which are produced in the pancreas.
Step-by-step explanation:
The pancreas plays a crucial role in neutralizing the acidic chyme entering the small intestine from the stomach. The pancreatic duct releases a solution rich in bicarbonate ions into the duodenum, the initial segment of the small intestine. Bicarbonate ions effectively neutralize the acidic environment, providing a suitable pH for the action of pancreatic enzymes and those produced by the small intestine itself.
This alkaline environment is essential for optimal enzymatic activity and absorption of nutrients. The pancreas thus acts as an exocrine gland, producing bicarbonate ions to protect the small intestine from the potentially damaging effects of hydrochloric acid.