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, the presence of normal microflora on the skin that competes with pathogens for nutrients and inhibits the growth of pathogens through production of lactic acid, the normal flora of the throat, colon and vagina occupies receptors which prevent 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 kicks in. Natural killer cells, neutrophils, macrophages, inflammation, fever, transferrin, and lactoferrin come into play to eliminate microbes. These also prevent infectious diseases. It is very important to prevent infection of the IV site. As long as the body's defense mechanisms are functioning properly and are not compromised, the process proceeds