Which of the following is an example of an anatomical defense mechanism?

The correct answer highlights a vital aspect of the body’s defense against pathogens: the role of phagocytes. Phagocytes, such as macrophages and neutrophils, are specialized cells capable of engulfing and digesting foreign particles, bacteria, and other harmful entities. This process, known as phagocytosis, is a crucial part of the innate immune response, which serves as the first line of defense against infections.

In the context of anatomical defense mechanisms, phagocytes act as an innate defense because they are unspecific—they do not target specific pathogens like antibodies do but respond to a variety of threats. Phagocytes move to the site of infection or inflammation, thereby contributing to the body’s overall ability to prevent disease.

Other examples provided in the question, while important in the immune response, do not fit the classification of anatomical defenses. For instance, interferons are signaling proteins involved in the immune response to viruses and are considered part of the chemical-mediated defenses. Lysozyme, which is an enzyme that breaks down bacterial cell walls, functions as a biochemical barrier, and stomach acids serve a protective role by destroying ingested pathogens. However, these are not classified as cellular defense mechanisms in the same direct manner as phagocytes.