What is secreted by the gastric mucous neck cells and pancreatic duct cells to neutralize stomach acid?

Bio carbonate ions

Explanation:

The pancreas secrets an aqueous mixture ( water, digestive enzymes and bicarbonate ions) during digestion of food substances from the stomach into the duodenum to begin the process of absorption and assimilation.

The pancreatic duct are lined with duct cells. These are cells which secretes HCO3- ,into the aqueous mixture. This ion is basic. Therefore it  neutralizes the acidity of the  of  the chyme to  released from the stomach to enable the pancreatic enzyme to work.

The bicarbonate ions also prevent the walls of the pancreases from getting burnt by the effect if the acidity of the chyme.

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explanation: