Final answer:
Adaptive immunity is triggered when the innate immune response fails to control an infection, leading to a highly specific immune response that includes memory against certain pathogens for long-term protection.
Step-by-step explanation:
Adaptive immunity occurs when the innate immune response is insufficient to eliminate pathogens and persistent infections occur after the initial defense response. Unlike the innate system, adaptive immunity is highly specific to the pathogen in question and also includes a memory feature that provides long-term protection and a quicker response upon re-exposure to the same pathogen.
The adaptive immune system includes two main types of responses: the cell-mediated immune response, which involves T cells, and the humoral immune response, which involves B cells and antibodies. Adaptive immunity is established after exposure to an antigen from a pathogen or vaccination. Ultimately, this defense mechanism comes into play to provide the host with a robust, targeted attack against a specific pathogen and prevent future infections with the same type of pathogen. Overall, this sophisticated arm strengthens the immune response and is instrumental in fighting off pathogens that the innate immune system alone may not be able to handle.