The immune system's primary defense mechanism includes which function?

The immune system's primary defense mechanism is centered around its ability to produce antibodies to fight infections. Antibodies are proteins that specifically recognize and bind to antigens, which are foreign substances such as pathogens (bacteria and viruses). This binding neutralizes the pathogens and marks them for destruction by other elements of the immune system.

When the body detects an infection, immune cells called B lymphocytes are activated and differentiate into plasma cells that produce large quantities of antibodies. This response not only helps eliminate the current threat but also contributes to immunological memory, allowing the body to respond more effectively to future infections by the same pathogen.

While other functions like lowering body temperature can be part of the immune response (as part of the fever to help fight infections), and digestive processes and muscle growth are essential for overall health, they do not directly pertain to the immune system's primary role of defending against infections.