Immunology - 1 IMMUNE SYSTEM AND IMMUNOLOGY Arno Helmberg These lecture notes accompany my lectures on immunology in the study

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Unformatted text preview: 1 IMMUNE SYSTEM AND IMMUNOLOGY Arno Helmberg These lecture notes accompany my lectures on immunology in the study module "Infection, immunology and allergology" at Innsbruck Medical University. The English version serves two purposes: as a learning aid for international students and to encourage German-speaking students to familiarize themselves with medical English; the lectures are delivered in German. The translation from the original German version is my own; I am afraid it will occasionally sound appalling to native English speakers, but it should at least be intelligible. Version 4.0 e Arno Helmberg 2000-2010 Pdf- version of http://helmberg.at/immunology.htm Terms of use: http://helmberg.at/terms.htm Every living organism, including our own, constantly has to be on guard not to be gobbled up by others, as it constitutes a potential source of valuable organic molecules. The ability to resist being used as "food" automatically confers a selective advantage. Over the course of evolution, this has led to the development of highly sophisticated defense systems in multicellular organisms. THE BASIC PROBLEM: COMBATING WHAT, EXACTLY? To maintain the integrity of our organism, it is essential to distinguish between biological structures that have to be fought off ideally, everything that poses a danger to our organismand structures that must not be attacked, e.g., the cells of our own body, or useful bacteria in our gut. This problem is not at all trivial, as dangerous attackers from the worlds of viruses, bacteria and parasites consist of largely the same molecules as the human body. Early in evolution, simple multicellular organisms developed a defense system activated by sensing typical molecular patterns associated with pathogens or distressed cells. This system is conserved and also works in humans. This innate, prefabricated, one-size-fits-all immune system is immediately available. In the best case, it nips an incipient infection in the bud; in the worst case, it keeps an infection in check for a few days. We are all absolutely dependent on this "old" system: infectious agents propagate so fast that we would be dead long before the second, evolutionarily younger system had a chance to kick in. Our most efficient defense mechanisms mount a custom-made counter-attack against the specific infectious agent invading our organism. We call this an adaptive immune response. Bespoke work takes time, meaning the system is simply not ready for use during the first days of an infection. These immune mechanisms fight "foreign" organic material that has entered our body. "Foreign" is not necessarily equivalent with "dangerous", but distinguishing "foreign" from "self" is easier to accomplish than distinguishing "dangerous" from "innocuous". This is because our immune system is able to learn what constitutes "self"; everything else is viewed with suspicion. As additional criteria to assess the level of danger, activation of the first, innate system is taken into account. 2...
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This note was uploaded on 01/16/2012 for the course BI 200 taught by Professor Potter during the Fall '11 term at Montgomery College.

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Immunology - 1 IMMUNE SYSTEM AND IMMUNOLOGY Arno Helmberg These lecture notes accompany my lectures on immunology in the study

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