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Chapter 24 - Slide 1 Chapter 24 The Immune System Function...

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Unformatted text preview: Slide 1 Chapter 24: The Immune System Function of the immune system • Defense system responsible for recognizing and combating foreign invaders • Two types: 1. Innate – what you are born with 2. Acquired – what your body learns Slide 2 Innate Immunity • The body’s first line of defense – always in place • It’s a general defense, not specific • Two basic types: 1. Outside the body (prevent infection) 2. Inside the body (fight infection) Slide 3 External Innate Immunity • Skin • Mucus membranes • Secretions Slide 4 Internal Innate Immunity White Blood Cells Phagocytic: protect the body by ingesting (phagocytosing) harmful foreign particles, bacteria, and dead or dying cells.) Neutrophils: They are the predominant cells in pus, accounting for its whitish/yellowish appearance. Macrophages: They are specialized phagocytic cells that attack foreign substances, infectious Microbes and cancer cells through destruction and ingestion.) • Natural Killer (NK) cells Defensive Proteins • Interferons: are proteins made and released by host cells in response to the presence of pathogens—such as viruses, bacteria, or parasites—or tumor cells. They allow communication between cells to trigger the protective defenses of the immune system that eradicate pathogens or tumors • Complement system: helps or “complements” the ability of antibodies and phagocytic cells to clear pathogens from an organism. It account for about 5% of the globulin fraction of blood serum. Over 25 proteins and protein fragments make up the complement system, including serum proteins, serosal proteins, and cell membrane receptors. Inflammatory Response • Inflammatory Response is a part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. • Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process. Inflammation is not a synonym for infection, even in cases where inflammation is caused by infection. Although infection is caused by a microorganism, inflammation is one of the responses of the organism to the pathogen. However, inflammation is a stereotyped response, and therefore it is considered as a mechanism of innate immunity, as compared to adaptive immunity, which is specific for each pathogen. Slide 5 Defensive proteins: Interferons Virus Viral nucleic acid Antiviral proteins block viral reproduction New viruses Interferon genes turned on DNA mRNA Interferon molecules Host cell 1 Makes interferon; is killed by virus Interferon stimulates cell to turn on genes for antiviral proteins Host cell 2 Protected against virus by interferon from cell 1 Slide 6 The Inflammatory Response Skin surface Pin Bacteria Chemical signals White blood cell Slide 7 Swelling Phagocytes and fluid move into area Phagocytes Blood vessel Tissue injury; release of chemical signals such as histamine Dilation and increased leakiness of local blood vessels; migration of phagocytes to the area Phagocytes (macrophages and neutrophils) consume bacteria and cell debris; tissue heals The Lymphatic System • Functions: 1. Return tissue fluid to the circulatory system 2. Fight infections Slide 8 Slide 9 Components of Lymphatic System Adenoid Tonsil Lymph nodes Right lymphatic duct, entering vein Thoracic duct, entering vein Lymph node Masses of lymphocytes and macrophages Thymus Valve Lymphatic vessel Blood capillary Tissue cells Interstitial fluid Thoracic duct Appendix Bone marrow Spleen Lymphatic vessels Lymphatic capillary Acquired Immunity • Only enacted after exposure to a specific pathogen 1. Only found in vertebrates 2. Differs from individual to individual 3. Stronger than innate 4. Highly specific (what works with one does not mean it will work with another) 5. Can amplify innate response 6. Has memory (Body can remember what it was exposed to) Slide 10 Antigen vs. Antibody • Antigen: Any foreign molecule that elicits an immune response (dust, mole, viruses etc…) • Antibody: Protein in blood plasma that physically binds to an antigen and helps to fight it Slide 11 Vaccination Slide 12 Active vs. Passive Immunity • Active: comes about naturally because of exposure to antigen, uses own antibodies • Passive: person gets premade antibodies 1. Fetus 2. Breast milk 3. Injections (does not provide long term immunity, only short term) 4. Antivenin (made from a horse) – used if bitten by a poison snake or spider Slide 13 Lymphocytes • White blood cells (spend most of their time in the tissues of the lymphocyte system) • Responsible for acquired immune defense • Originate in the bone marrow (They may not stay in the bone marrow) • B–cells (Bone marrow) vs. T–cells (Thymus) – Both are stem cells. Slide 14 B­cells • Remain in the bone marrow • Involved in humoral immune response – defensive proteins • Primary function: antibody secretion • Used to produce antibodies Slide 15 T­cells • Move from bone marrow to thymus (via blood) • Involved in cell – mediated immune response – defensive cells • Several functions: (They become activated) 1. Attack infected body cells – The T­Cells will destroy the bad cells. 2. Promote phagocytosis 3. Stimulate B­cells (Bone Marrow Cells) to produce antibodies Slide 16 How do T­ and B­cells work? • Produce surface proteins (outside of the cell) called antigen receptors • Antigen receptors are made by turning random genes on and off • Each t or b­cell will only make one type of receptor • Each receptor will bind only one specific antigen • Not all t or b­cell will be used • Once made (in marrow or thymus) are transported to lymph nodes and spleen Slide 17 Bone marrow Thymus Lymphocytes Stem cell Via blood Immature lymphocyte Antigen receptors T cell B cell Humoral immunity Cell-mediated immunity Via blood Lymph nodes, spleen, and other lymphatic organs Other parts of the lymphatic system Final maturation of B and T cells in lymphatic organ Slide 18 Clonal Selection Slide 19 Slide 20 Primary immune response Antigen receptor (antibody on cell surface) Antigen molecules Slide 21 Primary immune response Antigen receptor (antibody on cell surface) Antigen molecules First exposure to antigen Slide 22 Primary immune response Antigen receptor (antibody on cell surface) Antigen molecules First exposure to antigen Antibody molecules Endoplasmic reticulum Plasma (effector) cells secreting antibodies Memory cells Slide 23 Primary immune response Antigen receptor (antibody on cell surface) Antigen molecules First exposure to antigen Antibody molecules Endoplasmic reticulum Plasma (effector) cells secreting antibodies Memory cells Antigen molecules Second exposure to same antigen Secondary immune response Antibody molecules Endoplasmic reticulum Plasma (effector) cells secreting antibodies Memory cells LE 24-7b Slide 24 Antibody concentration Second exposure to antigen X, first exposure to antigen Y Secondary immune response to antigen X First exposure to antigen X Primary immune response to antigen X Primary immune response to antigen Y Antibodies to Y Antibodies to X 0 7 14 21 28 35 Time (days) 42 49 56 Slide 25 Humoral immunity makes which bind to B cell Antibodies Cell-mediated immunity T cell Infected body cell Self-nonself complex Antigens in body fluid Humoral Immunity • Destroys free antigens that are found in our body fluids • Uses antibodies to target and destroy invader Slide 26 Slide 27 Antibody A molecules Antigenbinding sites Antigenic determinants Antigen molecule Antibody B molecule Slide 28 Antigen-binding sites V V V V C C C C Heavy chain Light chain Slide 29 Binding of antibodies to antigens inactivates antigens by Neutralization (blocks viral binding sites; coats bacteria) Agglutination of microbes Precipitation of dissolved antigens Complement molecule Bacteria Virus Antigen molecules Bacterium Activation of complement system Foreign cell Enhances Leads to Phagocytosis Cell lysis Macrophage Hole Cell­Mediated Immunity • Helps battle invaders that have entered our body cells • Uses T­cells to identify infected cells • Helper T­cells: have many different roles, including activating other immune cells • Cytotoxic T­cells: attack body cells that are infected with pathogen Slide 30 Slide 31 Helper T­cells Self-nonself complex Microbe Macrophage B cell T cell receptor Protein stimulates cell division Helper T cell Proteins activates other B cells and T cells Self protein Antigen from microbe (nonself molecule) Antigen-presenting cell Humoral immunity (secretion of antibodies by plasma cells) Cytotoxic T cell Cell-mediated immunity (attack on infected cells) Cytotoxic T­cells Cytotoxic T cell binds to infected cell Protein makes holes in infected cell’s membrane and enzyme enters Self-nonself complex Infected cell Foreign antigen Cytotoxic T cell Hole forming Slide 32 Infected cell is destroyed Self vs Non­Self • Our body cells have proteins on their surfaces that our immune system can recognize (it sees those proteins and recognizes that they belong there) • Slide 33 Fall into two classes: • Class I: Found on all cells that have a nucleus • Class II: Found only in a few type of cells (B Cells, Activated T­ Cells and Macrophages) • Proteins are unique from individual to individual • Controlled by group of genes called the Major Histocompatibility Complex (MHC) There are hundreds of MHC genes. There are almost and infinite amount of genes that are possible. Autoimmune Disorders • Body’s immune system turns against body cells • Lupus: (Get skin rashes, fever, arthritis, kidney malfunction.) • Rheumatoid arthritis (Damaged of inflammation of the joints) • Diabetes (insulin dependent) cells kill cells • Multiple Sclerosis (when T­cells attack neurons.) Slide 34 Immunodeficiency Disease • A defect in one or more components of the immune system • SCID (Severe Combined Immuno Deficiency) – T cells are inactive and do not work like they are suppose to • Hodgkins – (Cancer of lymphocytes) Slide 35 Slide 36 Allergies B cell (plasma cell) Mast cell Antigenic determinant Allergen (pollen grain) enters blood stream Histamine Antibodies B cells make antibodies attach to mast cell Sensitization: Initial exposure to allergen Allergen binds to antibodies on mast cell Histamine is released, causing allergy symptoms Later exposure to same allergen Slide 37 Slide 38 1. Which type of immune response is in place at birth? A. Acquired B. Innate Slide 39 2. Which type of immunity cannot distinguish between different types of pathogens? A. Innate B. Accquired Slide 40 3. Lysozyme: A. Is an enzyme produced in saliva, sweat and tears B. Is part of the innate immune system C. Works by breaking down baterial cell walls, causing them to burst D. All of the above Slide 41 4. Neutrophils and macrophages are: A. Phagocytic cells B. Natural killer cells C. Proteins D. Cells that only protect our bodies against cancer cells and virus­infected cells Slide 42 5. Interferons are made by viruses. A. True B. False Slide 43 6. Interferon proteins are part of the complement system. A. True B. False Slide 44 7. Redness, swelling, and increased temperatures are characteristics of: A. Interferon action B. An accquired immune response C. The inflammatory response D. Natural killer cell action Slide 45 8. Which of these is not a response to histamine secretion? A. Blood vessel constriction at infected area B. Leaky blood vessels at infected area C. Increased blood flow at infected area D. Migration of phagocytes to infected area Slide 46 9. The inflammatory response can help prevent an infection from spreading by causing clot formation. A. True B. False Slide 47 10. The inflammatory response can be systemic. A. True B. False ...
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