The immune system protects the body through nonspecific and specific defenses. Nonspecific defenses are the body's first line of defense and include physical and chemical barriers like the skin, mucus, stomach acid, and resident bacteria. If pathogens get past these barriers, the immune system works to recognize and eliminate them by mounting an inflammatory response and using white blood cells.

1. Immunity

4. Nonspecific Defenses An animal's nonspecific defenses include physical barriers, competing resident microorganisms, and local agents, such as secretions that contain an antibacterial enzyme.

8. Inflammatory response