What lines the respiratory tract?

What lines the respiratory tract?

• A. Mucous membrane
• B. Skin
• C. Muscle
• D. Bone

Answer: (A)

Lining the respiratory tract is a mucous membrane. This moist epithelial layer, known as mucosa, covers airways from the nasal passages down to the bronchi. In many regions it is a pseudostratified ciliated columnar epithelium with goblet cells that produce mucus. The mucus traps dust, microbes, and other particles, and the tiny cilia rhythmically sweep it upward to the throat to be swallowed or expelled—the mucociliary escalator. This lining helps keep the airways moist, warm, and clear of debris, protecting the lungs. Skin, muscle, and bone do not line the airways, so the mucous membrane is the correct lining.

Lining the respiratory tract is a mucous membrane. This moist epithelial layer, known as mucosa, covers airways from the nasal passages down to the bronchi. In many regions it is a pseudostratified ciliated columnar epithelium with goblet cells that produce mucus. The mucus traps dust, microbes, and other particles, and the tiny cilia rhythmically sweep it upward to the throat to be swallowed or expelled—the mucociliary escalator. This lining helps keep the airways moist, warm, and clear of debris, protecting the lungs. Skin, muscle, and bone do not line the airways, so the mucous membrane is the correct lining.