The small intestine is protected from the corrosive action of hydrochloric acid in chyme by what?

The small intestine is protected from the corrosive action of hydrochloric acid in chyme by the bicarbonate ions secreted by the pancreas. The pancreas secretes bicarbonate ions into the duodenum, which helps to neutralize the acidic chyme that enters from the stomach. This helps to protect the small intestine from the damaging effects of the acidic chyme.