Specific Defense

Specific Defense - Specific Defense (The Immune System)

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Specific Defense (The Immune System) The immune system is the third line of defense. It consists of mechanisms and agents that target  specific antigens (Ags). An antigen is any molecule, usually a protein or polysaccharide, that can be  identified as foreign (nonself) or self (such as MHC antigens described below). It may be a toxin  (injected into the blood by the sting of an insect, for example), a part of the protein coat of a virus, or  a molecule unique to the plasma membranes of bacteria, protozoa, pollen, or other foreign cells.  Once the foreign antigen is recognized, an agent is released that targets that specific antigen. In the  process of mounting a successful defense, the immune system accomplishes five tasks:  Recognition.  The antigen or cell is recognized as nonself. To differentiate self from nonself,  unique molecules on the plasma membrane of cells called the 
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This note was uploaded on 11/10/2011 for the course PT 101 taught by Professor Staff during the Spring '10 term at Texas State.

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