What term describes the body's response to a harmful substance or organism?

The concept of the body's response to a harmful substance or organism is best captured by the term "Immune Response." This encompasses the complex biological processes that the body employs to defend itself against pathogens, such as bacteria, viruses, and other foreign invaders.

The immune response involves various components, including white blood cells, antibodies, and signaling molecules, all working together to identify and neutralize threats. The process can be divided into two main types: the innate immune response, which provides immediate defense, and the adaptive immune response, which develops targeted defenses based on specific pathogens after initial exposure.

While inflammation is a significant part of the immune response, as it is a localized reaction to infection or injury characterized by redness, swelling, heat, and pain, it does not encompass the entirety of the immune response. Similarly, homeostasis refers to the body's ability to maintain stable internal conditions despite external changes, which is a broader concept that also includes the immune response but is not specific to it. The antigen-antibody reaction is a specific interaction within the immune response but does not describe the entire process by which the body responds to harmful substances or organisms. Thus, the phrase "Immune Response" accurately encompasses the full range of actions the body takes in response to