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Unformatted text preview: Chapter 43 Three lines of defense against microbial attack • Nonspecific External o Skin o Mucous membranes • If barriers are penetrated, the body responds with nonspecific internal defenses o Phagocytic and natural killer cells o Inflammation o Fever • If nonspecific defenses are insufficient, the body responds with specific immune response o Cell-mediated immunity o Humoral immunity Lines of defense • 3 immune response: reaction to specific type of microbe and provides future protection • Involved 2 types of WBC called lymphocytes • B cells (bone) and T cells (thymus) o Step 1: recognize the invader Antibodies: protein produced by a host to bind to and inactivate foreign particles • Made by B cells o B cells have slightly different DNA sequence o There are 100 million B cells o They produce slightly different protein to bind with antibodies • Unique binding site so can only bind to one antigen • Binding to the antigen to antibody triggers the immune response • Genes for antibody parts recombine during development • Results is a random assortment of antibodies • Some will bind to body’s own proteins o These are destroyed before birth o Immune system distinguished “self” from “nonself” by retaining only those immune cells that do not respond to the body’s own molecules T-cell receptors on surface of T-cells • Made by T-cells • Act like antibodies; when antigen binds to receptors, T-cell responds o Step 2: launch the attack Humoral immunity by B cells is mediated by free antibodies in the bloodstream •...
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This note was uploaded on 01/31/2012 for the course BIOL 1202 taught by Professor Gregg during the Spring '08 term at LSU.
- Spring '08