9th BIOLOGY The Immune System

Non-specific Immunity Born with some immunity Helps prevent disease Helps slow disease progression First line of defense

Non-specific, cont. Physical Barrier- unbroken skin Skin oil acidic, inhibits pathogens Chemical barrier- saliva, tears, nasal secretions All contain lysozyme Mucus- sticky Cilia- sweep irritants away HCl in stomach, pH of 2

Non-Specific Response Cellular defense- WBCs Neutrophils, macrophages are phagocytic Engulf and destroy antigen Complement proteins- enhance phagocytic response Interferon-secreted by virally infected cells Binds to cells, produces antiviral proteins to prevent viral replication

Non-Specific Response, cont. Inflammatory response- Pathogens damage tissuechemicals released attract phagocytosis Increase capillary permeability to increase blood flow to the area Result is more WBCs to the rescue

Specific Immunity Lymphatic System- Lymphatic Organs- Includes organs and cell that filter lymph Lymph is tissue fluid that bathes body cells Lymphatic Organs- Contain lymphatic tissue, lymphocytes, connective tissue Lymphocytes- WBC produced in red bone marrow Include: lymph nodes, tonsils, spleen, thymus

Lymphatic Organs Lymph nodes- filter lymph and remove foreign particles Tonsils and adenoids- form a protective ring around nasal and oral cavities Spleen- stores blood and destroys damaged RBCs Thymus- above the heart, T cell maturation

B Cells B lymphocytes- Mature in bone marrow React with antigen Antibody factories- memory for antigen, quicker immune response upon next exposure. Antibody stimulation caused by vaccination or direct exposure to antigen

T Cells Mature in thymus First responder cell Activation of T cells required to continue cascade of events Macrophage activation- Macrophage engulfs antigen and displays pieces of it on surface T cells bind to presented antigen activates immune system, including B cells

T Cell Response Cytotoxic T cells- destroy pathogens and release cytokines Cytokines stimulate other immune cells to react

Passive and Active Immunity Passive- acquire antibodies from somewhere else Infants acquire some antibodies from their mothers to protect them until their immune system matures Receiving injections of antibodies from other humans or animals Anti-venom Hep A Rabies Tetanus

Passive and Active, cont. Active- you make the antibodies yourself Vaccination- series 1st shot- primary response Booster shot- secondary response- quicker and more intense Having disease Chickenpox

Immune System Failure HIV/AIDS- targets CD-4+ receptor on T cells Shuts down immune response by deactivating T cells Mild, flu-like symptoms upon first exposure Tests for HIV check for presence (HIV+) or absence(HIV-) of antibody to HIV