Basic and Clinical Sciences (BCSE) Practice Exam 2025 - Free BCSE Practice Questions and Study Guide.

Clara cells, also known as club cells, are specialized non-ciliated columnar cells found in the lining of the bronchioles within the respiratory system. Their primary function is to produce secretions that have anti-inflammatory properties, helping to protect the respiratory tract from irritants and pathogens. These secretions include proteins and enzymes that contribute to the immune defense and help maintain the integrity of the airway epithelium.

In the context of the respiratory system, Clara cells also play a role in detoxifying harmful substances inhaled into the lungs, as they can metabolize airborne toxins. Moreover, they are involved in the repair and regeneration of the bronchiolar epithelium after injury, making them significant for maintaining respiratory health.

In contrast, the other options refer to different types of cells within the respiratory system. Ciliated columnar cells are primarily responsible for moving mucus and trapped particles out of the lungs. Squamous cells lining the alveoli are involved in gas exchange and are distinctly different from Clara cells. Goblet cells, though also involved in secretion, are mucus-producing cells that are primarily found in the upper respiratory tract and are not characteristic of the deep airway structures where Clara cells reside. Thus, option B accurately reflects the unique and protective