What is the main purpose of mucus in the respiratory tract?

The main purpose of mucus in the respiratory tract is to trap dust and pathogens. The respiratory system is constantly exposed to environmental pollutants, allergens, and pathogens, and mucus plays a critical role in protecting the respiratory tissues. It is secreted by goblet cells and submucosal glands throughout the respiratory passages.

Mucus serves as a sticky barrier that entraps inhaled particles and microorganisms. When dust, pollen, bacteria, or viruses enter the airways, they adhere to the mucus, which helps to prevent these harmful substances from reaching the delicate lung tissue. Additionally, the action of cilia—tiny hair-like structures that line the respiratory tract—works in tandem with mucus by moving the trapped particles upward towards the throat, where they can be coughed out or swallowed.

While preventing dehydration is a secondary function, moisture is already maintained by the respiratory tract's design and the mucus itself. Similarly, facilitating gas exchange and enhancing oxygen absorption involve different physiological processes primarily occurring in the alveoli of the lungs rather than being directly influenced by mucus. Thus, trapping dust and pathogens remains the primary and crucial role of mucus in maintaining respiratory health.