The document summarizes the body's physical and immune defenses against pathogens. The physical defenses include the skin, hair, mucous membranes, saliva, tears, and digestive tract which act as barriers and contain substances that kill pathogens. When pathogens breach these defenses, the immune system responds through inflammation, white blood cells, and the lymphatic system. B-cells and T-cells work to identify and destroy pathogens while creating immunity. Maintaining a healthy lifestyle supports these defense systems.