How Your Body Fights Infection: 4 Key Defense Mechanisms

1. Physical barriers: The skin, mucous membranes, and other physical barriers prevent pathogens from entering the body.

2. Chemical barriers: The stomach acid, saliva, and other chemical barriers kill or inhibit the growth of pathogens.

3. Cellular defenses: White blood cells, including neutrophils, macrophages, and natural killer cells, attack and destroy pathogens.

4. Humoral defenses: Antibodies, produced by B cells, bind to pathogens and mark them for destruction by white blood cells.