Using the three lines of defense explain what could happen if a pathogen enters a human body?

Answer 1

If a pathogen enters the human body, the first line of defense, which includes physical barriers like skin and mucous membranes, attempts to block its entry. If the pathogen breaches these barriers, the second line of defense—a non-specific immune response involving white blood cells and inflammatory responses—activates to eliminate the intruder. If the pathogen persists, the third line of defense, which is the adaptive immune response, is triggered, leading to the production of specific antibodies to target the pathogen. Failure of these defenses can result in infection and disease.