Goblet Cells Secrete Mucus in Respiratory Epithelium

Steps:

• Identify goblet cells as flask-shaped epithelial cells in the respiratory tract lining.
• Recall their primary role in producing mucin, a glycoprotein that forms mucus.
• Link this to gas exchange system protection by moistening airways and trapping particles.
• Confirm function via secretion, distinguishing from other cell actions.

Why C is correct:

• Goblet cells are defined in biology as unicellular glands that release mucus to lubricate and protect respiratory surfaces.

Why the others are wrong:

• A: Surface area increase occurs via alveoli and microvilli, not goblet cells.
• B: Mucus movement is performed by ciliated epithelial cells.
• D: Trapping dust and pathogens is a role of the mucus layer, not the cells producing it.

Final answer: C