Final answer:
The cell that secretes large amounts of bicarbonate ions into the blood is the pancreatic duct cell, which is responsible for the bicarbonate-rich pancreatic juice that neutralizes stomach acid.
Step-by-step explanation:
The cell that secretes large amounts of bicarbonate ions into the blood is the pancreatic duct cell. Pancreatic duct cells are a part of the exocrine system, secreting pancreatic juice which contains not only various digestive enzymes but also a high concentration of bicarbonate ions. These bicarbonate ions are crucial as they help to neutralize the highly acidic chyme that enters the small intestine from the stomach, thereby maintaining the pH balance necessary for proper digestive function. On the contrary, other cells such as the pancreatic acinar cells, gastric parietal cells, and gastric chief cells do not primarily release bicarbonate into the bloodstream; their functions include the secretion of digestive enzymes, hydrochloric acid (HCl), and intrinsic factor respectively.