53). The thymus bone marrow, lymph nodes, spleen, liver, appendix, tonsils, adenoids, and lungs are all organs of the immune system. Body Defense The body's first line of defense includes the presence of physical and chemical barriers. These limit the entry of microorganisms into the body. “These include: intact skin and epithelial surfaces that act as mechanical barriers, presence of normal microflora on the skin that competes with pathogens for nutrients and inhibits pathogen growth through the production of lactic acid, normal flora of the throat, colon, and of the vagina that occupies the receptors that prevents colonization by pathogens. (Ogston-Tuck, 2014, p. 55). This also includes secretions that contain antibodies. When the first line of defense fails, the body's second line of defense comes into play. Natural killer cells, neutrophils, macrophages, inflammation, fever, and transferrin and lactoferrin go into action to eliminate microbes. These also prevent infectious diseases. Keeping the infection out of the intravenous site is very important. As long as the body's defense mechanisms function correctly and are not compromised, the process is complete