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Immune System

Immune System. A Boo Boo lets in germs. Like…Bacteria. Or a virus. A germ is still a germ…. Pathogen =agent that causes disease 2 . Antigen = foreign particle that triggers an immune response - often they are proteins on the surface

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Immune System

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  1. Immune System

  2. A Boo Boo lets in germs

  3. Like…Bacteria

  4. Or a virus

  5. A germ is still a germ…. Pathogen=agent that causes disease 2. Antigen= foreign particle that triggers an immune response - often they are proteins on the surface of viruses and bacteria

  6. Your Body’s Defenses AgainstDisease • Nonspecific Defenses: Attack all pathogens and antigens the same way • Specific Defenses: Immune Response – Attack pathogens that get past the nonspecific defenses

  7. Nonspecific Defenses This means that the identity of the pathogen/antigen is not important. The response is the same if a bacteria, virus, splinter or bullet invades the body.

  8. Nonspecific Defenses First Line Defenses Skin: Forms a physical barrier to pathogens -oils and sweat make skin acidic – inhibits the growth of pathogens -lysozyme-enzyme found in sweat and tears digests bacterial cell walls Mucus Membranes -layers of tissue which secrete mucus - found in body openings and the respiratory system - mucus traps pathogens

  9. Nonspecific DefensesSecond Line Defenses • Inflammatory Response • Damaged cells release histamines – chemical cry for help - histamines cause blood vessels to dilate (open) bringing blood to the area. - the dilated blood vessels become leaky releasing fluid and white blood cells in the infected area - causes swelling and redness in the damaged area - pus – fluid and dead cells forms • White Blood cells - Macrophages – “Big Eaters” engulf and kill pathogens - Neutrophils -engulf bacteria and release chemicals that kill the bacteria and themselves. -Natural Killer Cells (Lymphocyte)– recognize and kill virus infected cells and tumors

  10. Textbook page 925 Histamines are released Blood vessels dilate and leak

  11. Macrophage

  12. Nonspecific DefensesSecond Line Defenses (continued) • Temperature Response - Fever – -Body temp increases in response to infection - pathogenic bacteria don’t grow well at higher temp • Proteins - Complement Proteins: kill pathogens by punching a hole in the cell membrane - Interferon: a protein released by cells infected by viruses -causes nearby cells to release an enzyme preventing the virus from reproducing

  13. Fevers help eliminate pathogens

  14. Specific Defenses • Third Line of Defense Specific Defenses - identity of pathogen/ antigen must be known - the specific immune response is tailored to the specific pathogen

  15. Specific DefensesMacrophage Links Nonspecific to Specific When a macrophage engulfs a pathogen, it displays the viral antigen on its surface The antigen is joined to a MHC (Major Histocompatibility Complex) The MHC is a protein on the surface of all vertebrate cells The anitgen must be bound to the MHC for the Helper T Cell to recognize it

  16. Specific DefensesHelper T Cells • Receptor proteins on helper T cells (TH) bind to viral antigens displayed on the macrophage

  17. Specific Defenses Cell Mediated Response • Receptor proteins on the cytotoxic T cells (TC) bind to viral antigens displayed by infected cells • Cytotoxic T cells (TC) punch a hole in the cell’s membrane • Your body produces many cytotoxic T cells (TC) - each specific to a particular antigen

  18. Specific DefensesAntibody Mediated Response • B cells divide and develop into plasma cells • Plasma cells release large numbers of antibodies • Antibodiesbind to antigens on pathogens • Antibodies cause pathogens to clump holding them until macrophages can engulf them • Antibodies are specific to a particular pathogen-your body produces the antibodies in response to infection

  19. The Specific Defense has two phases • Primary Immune Response: -Occurs when the body has never encountered a pathogen /antigen before. -Immune system goes through all of the steps -After the threat has passed, MEMORY Cells are made. • Secondary Immune Response: The next time the pathogeninvadesMEMORY Cells identify the invader and a massive volume of antibodies are released, destroying the invader before you feel ill. You are immune!

  20. Vaccines Polio 1952 60,000 cases in the US 3000 fatalities 1955 Salk vaccine 1979 eliminated in US

  21. How do vaccines work? Vaccines are made up of weakened viral particles. The weakened particles stimulate a small number of antibodies and memory cells to be produced. Primary Immune Response When a the pathogen attacks, the antibody production is larger. Secondary Immune Response

  22. Immune Response

  23. Vocabulary Pathogen B cells T cells Macrophages Nonspecific Defense Vaccines Primary Immune Response Secondary Immune Response

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