Chemotherapy Biotherapy Certification ONS Practice Test 2025 - Free Practice Questions and Study Guide

Phagocytosis is the process by which certain cells, known as phagocytes, ingest and eliminate pathogens, such as bacteria and other foreign substances. This immune mechanism is a crucial aspect of the innate immune response, where phagocytes—such as neutrophils and macrophages—recognize, engulf, and digest harmful microorganisms or debris.

During phagocytosis, the pathogen is surrounded by the cell membrane of the phagocyte, forming a phagosome, which then fuses with lysosomes containing digestive enzymes. This enzymatic action effectively destroys and removes the pathogens from the body, playing a vital role in the host's defense against infections.

Other immune mechanisms mentioned in the choices, while essential to immune function, do not specifically involve the direct ingestion of pathogens. Inflammation refers to the body's response to injury or infection, characterized by swelling and redness. Immunization involves the introduction of antigens to stimulate an adaptive immune response, without directly involving the ingestion of pathogens. Cell-mediated immunity primarily involves T cells and does not focus on the ingestion of pathogens in the way phagocytosis does.