Bisc 102 test 3

Bisc 102 test 3 - Specific defenses: the immune system The...

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Specific defenses: the immune system The immune system Provides a third line of defense if the non specific defense fail to ward off invaders Antigens o Are foreign substances that provokes an immune response ( they prime the immune system) Antibodies o Are proteins found in blood plasma that recognize particular antigens Immunity o Is resistance to specific invaders o Is usually acquired by natural infection Active immunity o Is acquired by being in contact with an antigen (via infection or vaccination) o Your body produces its own antibodies Passive immunity o Is acquired by receiving pre-made antibodies o Only for a little time Recognizing the invaders Lymphocytes (white blood cells) are the #1 players o B cells, which develop in the bone marrow o T cells, which become specialized in the thymus o Figure 24.9 Humoral immunity (by B cells) o Invaders in your blood or lymph o Antibodies are secreted and sent to the site of the infection Cell-medicated immunity (by T-cells) o T cells attack infected body cells o T cells also stimulate phagocytosis and antibody production by B cells Antibodies o Proteins that serve as molecular weapons of defense o Produced by B cells and travel until they find their specific antigen = humoral immunity o Figure 24.10 Two related functions of antibodies: o Recognize and bind to a certain antigen o Counter its effect Flags the antigen as foreign Can physically block the antigen Can make the invaders clump so they are easy preys for
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phagocytes Figure 24.11 Immunological Memory The first time you are exposed, the primary immune response takes several days to produce effectors cells via clonal selection Clonal selection also produces memory cells, which can last decades in the lymph nodes o Memory cells produce the secondary immune response when the same antigen in encountered again o Much faster than primary response T Cells Helper T cells o Bind to other white blood cells that have previously encountered an antigen o Figure 24.12 o Figure 24.13 Cytoxic T Cells o Are the only T cells that actually kill other cells o Figure 24.14 Immune Disorders Allergies o Are abnormal sensitivities to antigens in the environment Allergens o Are antigens that cause allergies The symptoms of an allergy result form a two – stage reaction sequence Figure 24.15 Anaphylactic shock Is an especially dangerous type of allergic reaction Can be counteracted with injections of epinephrine Autoimmune diseases The body’s immune system o Normally reacts only against foreign (nonself) substance o Generally rejects transplanted organs In autoimmune diseases o The immune system turns against the body’s own molecules Type 1 diabetes Rheumatoid arthritis Multiple sclerosis Lupus In immunodeficiency diseases o Immune components are lacking, and infections recur
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HIV, the AIDS virus o Attacks helper T cells, crippling both humoral and cell-mediated immunity
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This note was uploaded on 04/07/2008 for the course BISC 102 taught by Professor Thibeault during the Fall '08 term at Ole Miss.

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Bisc 102 test 3 - Specific defenses: the immune system The...

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