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IMMUNE RESPONSE Nonspecific Defenses include Skin Sweat Oils Lysozyme White Blood Cells -Macrophages The human body has a number of systems developed to try to protect it from foreign invaders. Some of these are very specific and are designed to stop one version of a bacteria or virus. Others are far more general and nonspecific. The specific defenses are almost 100% effective. They take some time to develop and come at a high cost in energy. Nonspecific defenses are far less effective against a determined invader, but work well against a number of potential causes of disease at fairly low cost to the body. Skin is an example of such a defense system. We rarely have infections on or just under the skin. If the skin is broken such infections are far more likely. Sweat contains an enzyme, lysozyme, whose function is to break apart bacteria. It is not effective against all of them, but it works well against many. Oils secreted by the skin offer another barrier and they also function to keep the skin supple and to help prevent cracking that can lead to infection. Some white blood cells search the body for foreign cells and consume them. These may be bacteria, viruses or even body cells that have been damaged enough to not be functioning properly. Inflammatory Response Occurs as a result of tissue damage Damage releases chemical signals - histamine Increased fluid leakage and migration of phagocytes Cells consume (phagocytosis) bacteria and cell debris. The inflammatory response is another nonspecific defense. If you hit your thumb with a hammer a number of things will happen. Along with becoming sore it will probably swell, turn a bit red and become warm to the touch. The damage to tissue released a number of chemicals including histamine. These chemicals caused the surrounding blood vessels to become more permeable to fluid and also white blood cells. This causes the swelling and the heat. The white blood cells search for foreign invaders and also consume damaged tissue so that repairs can begin. These nonspecific defenses work well, but if they were all we had we would die. We have also developed some very specific and very effective means of limiting infection.
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Define Antigen - a large molecule that elicits an immune response. Usually protein. Not a molecule normally found in the body. Antibody - a plasma protein that interacts with a specific antigen. Immunity - resistance to specific invaders An antigen is a molecule (almost always a protein or at least mostly protein) that the body does not recognize. The assumption it makes is that if it is foreign it probably comes from some organisms that means me harm. Antibodies are special proteins that are made that can bind to very specific
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