Mucus Production by Goblet Cells in Respiratory Epithelium

Steps:

• Identify the gas exchange system as the respiratory tract, where mucus protects airways from dust and pathogens.
• Recall that mucus is secreted by specialized cells in the epithelial lining to trap particles.
• Differentiate cell types: goblet cells produce mucus, while others have different roles like movement or immunity.
• Match the function to the choice: only goblet cells directly secrete mucus.

Why B is correct:

• Goblet cells are flask-shaped epithelial cells in the respiratory tract that secrete mucin, forming a protective mucus layer as defined in respiratory histology.

Why the others are wrong:

• A. Ciliated cells: Beat to move mucus but do not produce it.
• C. Lymphocyte cells: White blood cells involved in immune responses, not secretion.
• D. Red blood cells: Transport oxygen in blood, absent from airway epithelium.

Final answer: B