What is the primary function of the immune system?

The primary function of the immune system is to defend against pathogens and diseases. This complex network of cells, tissues, and organs works together to identify and eliminate harmful invaders such as bacteria, viruses, fungi, and parasites. When the body detects foreign substances, the immune response is activated, leading to the production of specialized cells and antibodies that target and destroy these pathogens.

This function is vital for maintaining overall health and preventing infections, as a well-functioning immune system can efficiently protect the body from a variety of diseases. In contrast, the other options relate to different body systems: nutrient transport and provision of energy is primarily associated with the digestive system, fluid balance is managed by the renal and circulatory systems, and body temperature regulation involves thermoregulatory processes and the involvement of various organ systems. Understanding the immune system's role helps students appreciate its importance in overall health and wellness.