Infection and Response Practice Test

Innate, non-specific immune responses act as the first line of defense and respond quickly to many pathogens without prior exposure. Physical barriers like skin and mucous membranes keep pathogens out. If a breach occurs, the inflammatory response rushes in, bringing immune cells to the site, which helps contain the infection and promote healing. Fever can rise to create an environment less favorable for pathogens and to boost immune cell activity. Phagocytes, such as neutrophils and macrophages, rapidly engulf and destroy invaders, while natural killer cells target and kill infected or stressed cells. Taken together, these non-specific defenses slow or limit pathogen spread while the more targeted adaptive immunity gears up, producing antibodies and activating specific T cells to clear the infection. Antibodies and T cells are part of that later, specific response, not the immediate non-specific stage. While blood clotting can help localize injury, the hallmark non-specific defenses described here—barriers, inflammation, fever, phagocytosis and NK cells—best capture the early, generic response before adaptive immunity acts.