Final answer:
When the immune system detects a pathogen in the body, it initiates an immune response to defend against the invader. This response involves various cells and molecules of the immune system working together to eliminate the pathogen.
Step-by-step explanation:
When the immune system detects a pathogen in the body, it initiates an immune response to defend against the invader. This response involves various cells and molecules of the immune system working together to eliminate the pathogen.
The immune response can be classified into two types: innate and adaptive. The innate immune response is the first line of defense and is non-specific, meaning it targets all pathogens rather than specific ones. It includes barriers like skin, tears, and mucus, as well as cells like macrophages and natural killer cells that engulf and destroy pathogens. On the other hand, the adaptive immune response is specific and tailored to the particular pathogen. It involves the activation of B and T cells that produce antibodies or directly attack infected cells, respectively.
Overall, the immune system's cells respond to the presence of a pathogen by mounting an immune response through both innate and adaptive mechanisms, with the goal of eliminating the pathogen and protecting the body from infection.