How the Body Defends Itself Against the Influenza Virus

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This essay will outline the mechanisms by which the body defends itself against the Influenza Virus, more commonly referred to as ‘Flu’. Influenza viruses need to infect host cells in order to replicate. Most flu viruses are destroyed by the innate immune mechanisms involving components such as macrophages, interferons and natural killer cells, however some manage to avoid being detected by these early defence mechanisms and so are eliminated by the adaptive immune response. Although the skin barrier is an effective defence mechanism to most microorganisms, there are three ‘passageways’ that can provide a ‘direct route for microbes to enter the body’ (D.Chiras, 2007:278). The respiratory tract is the most susceptible way for the flu virus to penetrate the body as flu is an airborne virus transmitted via respiratory droplets ‘as a direct result of coughing or sneezing or direct close personal contact’ (Perry,2010:11-15). These droplets enter the nasal cavity of a second host where small hairs and a mucus membrane are present. They trap microbes before they can penetrate further into the body; however some microbes evade capture and continue into the lower respiratory tract. The respiratory tract, consisting of mucus and ciliated epithelial cells, catches more foreign particles and sweeps them up and out towards the pharynx (see Figure 1), where it is swallowed in to the stomach. The gut flora within the stomach secretes chemicals such as lactic acid which lower the pH,
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