What is the body’s defense network against infections called?

The body's defense network against infections is known as the immune system. This complex system comprises various cells, tissues, and organs that work together to identify and eliminate pathogens such as bacteria, viruses, and other foreign invaders. The immune system is vital in maintaining health by distinguishing between the body's own cells and harmful microorganisms. It is characterized by specific responses to particular threats, including the production of antibodies and the activation of white blood cells that target and destroy harmful agents.

Other systems mentioned, like the respiratory, circulatory, and nervous systems, play essential roles in the body but do not specifically focus on defending against infections. The respiratory system is primarily responsible for gas exchange, the circulatory system distributes blood and nutrients throughout the body, and the nervous system coordinates movements and responses. None of these systems directly counteract pathogens or infections the way the immune system does.