Which type of immunity is developed after exposure to a pathogen?

Active immunity is the type developed after exposure to a pathogen because it arises when the immune system is stimulated to produce antibodies and memory cells in response to the presence of a foreign invader. This exposure can occur through natural infection, where the body encounters pathogens directly, or through vaccination, where a harmless component of the pathogen is introduced to trigger an immune response without causing disease.

In active immunity, the body learns to recognize and remember the specific antigens associated with the pathogen, allowing for a faster and more effective response upon subsequent exposures. This long-lasting immunity is a key feature, as it typically provides protection for many years, sometimes even a lifetime.

Other types of immunity, such as passive immunity, involve the transfer of antibodies from another source, which does not engage the recipient's immune system in the same way and is often temporary. Innate immunity refers to the body’s first line of defense through physical and chemical barriers, and adaptive immunity is a broader category that encompasses the specifics of the immune response but doesn’t exclusively focus on the effect of the pathogen exposure itself in generating active immunity.