Asbestos Hazard Emergency Response Act (AHERA) Certification Practice Exam

What is the primary defense mechanism in the lungs against asbestos fibers?

1. Alveoli

2. Cilia

3. Bronchi

4. Macrophages

The correct answer is: Cilia

The primary defense mechanism in the lungs against asbestos fibers is the cilia. Cilia are tiny, hair-like structures lining the respiratory tract that play a crucial role in trapping and expelling foreign particles, including asbestos fibers, from the airways. They beat in a coordinated manner to move mucus, which traps inhaled particles, toward the throat where it can be swallowed or expelled. This mechanism is essential for maintaining respiratory health and preventing particles from penetrating deeper into the lungs. While the other options also have roles in respiratory function, they do not serve as the primary defense against inhaled asbestos fibers. Alveoli are the tiny air sacs where gas exchange occurs but do not contribute directly to trapping particles. Bronchi are the large air passages that lead to the lungs, providing a pathway for airflow, but they do not have a defense function. Macrophages are immune cells in the lungs that help to engulf and digest particles, including asbestos, but they are part of a secondary response rather than the initial defense mechanism provided by cilia. Thus, cilia are fundamentally important in the first line of defense against asbestos particles in the respiratory system.