Biological Systems MCAT Practice Exam

Which structure within the respiratory tract is responsible for producing mucus?

1. Goblet cells

2. Squamous epithelial cells

3. Alveolar macrophages

4. Ciliated epithelial cells

The correct answer is: Goblet cells

Goblet cells are specialized epithelial cells found throughout the respiratory tract, particularly in the trachea and bronchi. Their primary function is to secrete mucus, which plays a crucial role in maintaining respiratory health. Mucus acts as a protective barrier, trapping dust, pathogens, and other particles inhaled during breathing, thereby preventing them from reaching the delicate lung tissues. In addition to protecting the respiratory system, the mucus also facilitates the movement of cilia, which are hair-like projections on the surfaces of certain epithelial cells that help move mucus out of the respiratory tract when it is expelled or swallowed. While ciliated epithelial cells are important for mucus movement, they do not produce mucus; rather, they work to transport the mucus produced by goblet cells. Squamous epithelial cells are primarily involved in providing a protective layer rather than producing secretions. Alveolar macrophages, on the other hand, are immune cells located in the alveoli that play a role in engulfing pathogens and debris but do not produce mucus. Thus, goblet cells are uniquely responsible for mucus production in the respiratory system.