Which body part is involved in a non-mechanical body defense?

The nose plays a crucial role in non-mechanical body defenses due primarily to its function in respiratory immunity. It is equipped with mucous membranes that trap pathogens, dust, and other foreign particles, preventing them from entering the respiratory system. Additionally, the nose contains cilia—tiny hair-like structures that help move trapped particles out of the airways, ensuring they do not reach the lungs.

This non-mechanical defense is part of the broader immune response that includes the production of antimicrobial substances in the mucus, which can neutralize or destroy pathogens. In contrast, other options like the skin serve as a mechanical barrier rather than as a non-mechanical defense. The stomach is involved in breaking down food and contains acids to kill pathogens but does not directly fit the definition of non-mechanical defense. The liver is essential for various metabolic functions and detoxification processes but does not specifically engage in non-mechanical defenses against pathogens in the same way the nose does.