What is the purpose of mucus in the respiratory system?

• A. To provide structural support to the lungs
• B. To facilitate the inhalation of air
• C. To trap dust, pathogens, and foreign particles
• D. To increase oxygen absorption

Answer: (C)

Mucus plays a vital role in the respiratory system primarily by trapping dust, pathogens, and foreign particles. It is produced by goblet cells and is present throughout the respiratory tract, including the nasal passages, trachea, and bronchi. The mucus acts as a sticky barrier, capturing particulate matter and microorganisms that are inhaled along with air. By trapping these potentially harmful substances, mucus helps prevent them from entering the lungs, where they could cause infections or other respiratory issues.

Additionally, the mucus facilitates the movement of trapped particles out of the respiratory system. Cilia, tiny hair-like structures on the surface of respiratory epithelial cells, beat in a coordinated manner to move the mucus upward towards the throat, where it can be swallowed or expelled. This mucociliary escalator is crucial for maintaining the cleanliness of the airways and protecting lung health.

While other options mention various functions, they do not correctly capture the central role of mucus in maintaining respiratory health. Providing structural support, facilitating air inhalation, or increasing oxygen absorption are not primary functions associated with mucus in the respiratory system.