Final answer:
Respiratory cilia are designed to keep air pathways clear by trapping dust and mucus, which are then expelled out of the body. Damage to the cilia, such as that caused by smoking, can lead to an increased risk of respiratory problems due to inefficient clearing of mucus.
Step-by-step explanation:
Respiratory cilia have the critical role of keeping air passages free of dust and mucus. Cilia are microscopic, hair-like projections found on cells that line the respiratory system. They function as a part of the body's defensive mechanisms by trapping and removing dust, germs, and other foreign particles from the airways. This is done through the production of mucus which ensnares these particles. The cilia then move in a wave-like motion to sweep the mucus, along with the captured particulates, upward toward the throat where it can be expelled.
When these cilia are damaged, such as through exposure to cigarette smoke which contains tar and other harmful substances, their ability to remove particles is compromised. Smoking not only destroys or paralyzes the cilia but also causes the lungs to produce more mucus. This excess mucus cannot be effectively moved due to the damaged cilia, leading to a persistent cough as the body attempts to clear the particulates. This situation heightens smokers' susceptibility to respiratory ailments.