Final answer:
The term "immune system" was first used in 1967 by Niels Jerne to describe the collection of barriers, cells, and proteins that protect the body. The immune system consists of the innate and adaptive immune systems, which work together to defend against pathogens.
Step-by-step explanation:
The term "immune system" was used for the first time in 1967 by Niels Jerne to describe the collection of barriers, cells, and soluble proteins that interact and communicate with each other in the body's defense against pathogens and other threats. The immune system is a complex multilayered system, consisting of two types of defense systems: the innate immune system and the adaptive immune system. The innate immune system provides a quick but nonspecific response, while the adaptive immune system mounts a highly specific response to substances and organisms that do not belong in the body, and it has a memory system that allows it to respond with greater intensity upon reencountering a pathogen.