Final answer:
Mucus neck cells secrete acidic mucus in the stomach, distinct from goblet cell mucus, while parietal cells produce hydrochloric acid and intrinsic factor. The respiratory tract's pseudostratified columnar epithelia and cilia help protect against inhaled irritants.
Step-by-step explanation:
The two types of cells mentioned are mucus neck cells and parietal cells. Mucus neck cells are found in the gastric glands of the stomach and secrete a thin, acidic mucus different from that of goblet cells. On the other hand, parietal cells, which were not directly described in the provided reference, are known to secrete hydrochloric acid and intrinsic factor in the stomach, essential for digestion and absorption of vitamin B12 respectively.
Epithelial tissues play a vital role in various organs, exemplified by pseudostratified columnar epithelia in the respiratory tract, which appear stratified due to the nuclei's arrangement but are indeed a single layer. These cells, along with goblet cells, help protect the respiratory system by trapping irritants with mucus, aided by the motion of cilia.