Final answer:
Parietal cells secrete hydrochloric acid (HCI) into the lumen of the stomach and intrinsic factor into the bloodstream.
Step-by-step explanation:
Parietal cells secrete hydrochloric acid (HCI) into the lumen of the stomach and intrinsic factor into the bloodstream.
Hydrochloric acid (HCI) is responsible for the high acidity of the stomach contents, which is needed to activate the protein-digesting enzyme, pepsin. It also helps to kill bacteria and denature proteins for digestion. Intrinsic factor is necessary for the absorption of vitamin B12 in the small intestine.