Final answer:
The immune response is a complex cascade of events that occurs following activation by an invading substance. It involves cellular and molecular attacks such as inflammation, phagocytosis, cytokine release, destruction by NK cells, and/or activation of the complement system.
Step-by-step explanation:
The immune response is a complex cascade of events that occurs following activation by an invading substance. It is a part of the immune system, which comprises both innate and adaptive immune responses. The innate immune response occurs naturally because of genetic factors or physiology and serves as a first responder to pathogenic threats. It involves cellular and molecular attacks such as inflammation, phagocytosis, cytokine release, destruction by NK cells, and/or activation of the complement system.