Animal Form & Function Immune System AP Biology

Nonspecific Defenses  Do not discriminate  Present at birth  Prevent approach of pathogens

Nonspecific Defenses  Physical barriers  Skin  Creates effective barrier  Multiple layers  Keratin  Desmosomes

Nonspecific Defenses  Physical barriers  Secretions  Oil, sweat, mucus  Wash away pathogens  Lysozyme kills bacteria

Nonspecific Defenses  Phagocytes  Neutrophils  Phagocytize cellular debris & invading bacteria

Nonspecific Defenses  Phagocytes  Eosinophils  Target foreign compounds or pathogens coated with antibodies

Nonspecific Defenses  Phagocytes  Macrophage  Derived from monocytes  Large

Nonspecific Defenses  Phagocytes  NK cells  Natural killer cells  Large lymphocytes  Destroy abnormal cells  Constantly monitor normal tissues

Nonspecific Defenses  Inflammatory response  Histamine released by basophils  Blood vessels dilate  Increased blood flow to damaged area  Phagocytes mobilized  Complement activated 20 proteins React in chain reaction Attacks & breaks down cell walls

Specific Defenses  Target specific antigen  Involves lymphocytes  Remembers antigens encountered in the past  Ignores self and attacks nonself

Specific Defenses  Cell-Mediated Immunity  Provides defense against abnormal cells & pathogens inside living cells  Involves T cells (green cell)

Specific Defenses  Cell-Mediated Immunity  Antigen engulfed by macrophage  Antigen broken down  Macrophage presents pieces of antigen on cell membrane  Specific T cell binds to antigen pieces  Specific T cell activated

Specific Defenses  Cell-Mediated Immunity  Activated T cell divides & differentiates Helper T cells – stimulate immune response Cytotoxic T cells – killer T cells Memory T cells – remember encountered antigens; activated with 2 nd exposure Supressor T cells – slows things down

Specific Defenses  Antibody-Mediated Immunity  Provides defense against antigens & pathogens in body fluids  Involves B cells

Specific Defenses  Antibody-Mediated Immunity

Specific Defenses  Antibody-Mediated Immunity  Specific B cell activated  Activated B cell divides & differentiates Plasma cells  Produce antibodies Memory B cells  Remember encountered antigens  Activated with 2 nd exposure

Specific Defenses  Antibody-Mediated Immunity  Specific B cell activated  Activated B cell divides & differentiates Plasma cells  Produce antibodies Memory B cells  Remember encountered antigens  Activated with 2 nd exposure

Specific Defenses  Primary Immune Response  Period I  B cell activated  Activated B cell divides & differentiates  Plasma cells produce antibodies

Specific Defenses  Secondary Immune Response  Period II  Memory B cell activated  Faster response  Stronger response  Less lag time after exposure