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 2nd 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 2nd 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 2nd 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 Strongerresponse

Less lag timeafter exposure