Parietal cells are specialized cells located in the lining of the stomach. Their primary function is to produce and secrete hydrochloric acid, which helps create an acidic environment necessary for digestion. This acid also activates digestive enzymes and aids in breaking down food. In addition to hydrochloric acid, parietal cells secrete intrinsic factor, a protein essential for the absorption of vitamin B12 in the intestines. A deficiency in intrinsic factor can lead to pernicious anemia, a condition characterized by a reduced number of red blood cells. Proper functioning of parietal cells is crucial for overall digestive health.