bio - The human immune system is complex and extensively...

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The human immune system is complex and extensively distributed throughout the body to protect us from infectious agents such as bacteria, viruses, and parasites. It also works to maintain healthy tissues; however, the immune response can also be a source of disease when it malfunctions. 1
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We will cover the basic ideas of immunology such as barriers to pathogen entry, the inflammatory response and the specific immunity associated with antibodies. Also, we will relate these concepts to the preventative efforts of vaccination. A common metaphor for the immune system is an army fighting a war against an invading enemy; there are many parallels that can be drawn and this can facilitate understanding to a certain extent. 2
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3 Here’s an overview of animal immune systems. Even though it’s organized here as nice, neat boxes; the immune system functions listed have a great deal of overlap and continuity. However, this table does allow us to identify the many processes. Let’s focus on an area commonly referred to an innate immunity and specifically we will look at external barriers first.
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External barriers include not only the skin but also the linings of various organs that are open to the external environment (like the gut, respiratory tract, vagina, urethra). Our skin is made of several different layers; however, the outermost layer is made of dead cells filled with a protein called keratin (found also in finger nails and hair). This outer layer is continually sloughed off to be replaced with newly dying cells emerging from deeper layers. This serves as a good barrier to pathogens as long as the skin remains intact. Antimicrobial secretions include the protective enzyme called lysozyme found in our eye secretions (tears) that specific break protein bonds in the cell wall of certain bacteria. Our respiratory tract is lined with mucus secreting cells and cilia that continually transport foreign materials including microbes up and out of the system. Finally, our body is colonized with bacterial and fungal species that co- exist with us and actually help us in many ways. This includes the naturally occurring bacteria in our intestines (called gut flora) that provide nutrients but also prevent colonization of pathogenic bacteria. There’s currently a National Institute of Health study going on to better understand the microbial diversity and function of our flora ( http://commonfund.nih.gov/hmp/ ). Also, here’s a fascinating opinion article on the role of our microflora and the emerging diseases of post-industrial societies: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1618379/ 4
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coordinated in a complex set of events that is called the inflammatory response. Let’s look specifically at this coordinated response and examine the component elements such as phagocytosis in the context of inflammation. 5
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bio - The human immune system is complex and extensively...

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