Final answer:
Parietal cells are responsible for secreting hydrochloric acid and intrinsic factor in the stomach. Hydrochloric acid helps with protein digestion and denaturing proteins, while intrinsic factor is necessary for the absorption of vitamin B12.
Step-by-step explanation:
Parietal cells are specialized epithelial cells in the gastric glands of the stomach. They secrete hydrochloric acid (HCl) and intrinsic factor. HCl is responsible for the high acidity of the stomach contents, which helps activate the protein-digesting enzyme pepsin and denature proteins for enzymatic digestion. Intrinsic factor is necessary for the absorption of vitamin B12 in the small intestine.