The Innate Immune Systems And The Acquired Or Adaptive Immune System

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The immune system can broadly be divided into two categories: the innate immune system and the acquired or adaptive immune system. The innate system acts like the first line of defense, it works by recognizing a broad range of pathogens on the basis of their patterns and certain molecules that are different from those found in the organism e.g. the human innate immune system will recognize peptidoglycans that are found in bacteria but not humans. The innate system consists of physical barriers like the skin and mucosal membrane and other cells like natural killers and cytokines. It is thought, as of now, that the innate immune system has no memory. The acquired or adaptive immune system on the other hand is much more specific. (Warrington, Watson, Kim, & Antonett, 2011) Rick M Maizels et al state that the reason natural selection has favored so much variation in the immune response is because in order to survive, the organism must illicit a strong response against a large number of invading pathogens. Had this response not been a highly evolved one, our immune system would not have been able to fend of many complex pathogens which can themselves evolve rapidly to encounter the hosts’ immune system. (Maizels & Nussey, 2013)
Initially, only the innate immune system existed, but as organisms evolved another set of immune cells starting to develop. This can be seen from the immune system of jawless fish like lamprey. These organisms don’t essentially have an adaptive immune

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