1. Immune System

2. An open wound allows ‘germs’ to enter the body.

3. Like…Bacteria

4. Or a virus

5. A germ is still a germ…. 1. Pathogen=agent that causes disease 2. Antigen= foreign particle that triggers an immune response. immune response. - often they are proteins on the surface of viruses and bacteria

6. Your Body’s Defenses Against Disease Nonspecific Defenses: Attack all pathogens and antigens the same way Nonspecific Defenses: Attack all pathogens and antigens the same way Specific Defenses: Immune Response – Attack pathogens that get past the nonspecific defenses. 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 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 -lysozyme-enzyme found in sweat and tears digests bacterial cell walls Mucus Membranes-layers of tissue which secrete mucus Mucus Membranes-layers of tissue which secrete mucus - found in body openings and the respiratory - found in body openings and the respiratory system system - mucus traps pathogens - mucus traps pathogens

9. Second Line Defenses Inflammatory Response Inflammatory Response Damaged cells release histamines Damaged cells release histamines - histamines cause blood vessels to dilate (open) bringing blood to the area. - 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 - the dilated blood vessels become leaky releasing fluid and white blood cells in the infected area - causes swelling and redness in the damaged area - causes swelling and redness in the damaged area - pus – fluid and dead cells forms - pus – fluid and dead cells forms

10. White Blood cells White Blood cells - Macrophages – “Big Eaters” engulf and kill pathogens - Macrophages – “Big Eaters” engulf and kill pathogens - Neutrophils-engulf bacteria and release chemicals that kill the bacteria and themselves. - Neutrophils-engulf bacteria and release chemicals that kill the bacteria and themselves. - Natural Killer Cells – recognize and kill virus infected cells and tumors - Natural Killer Cells – recognize and kill virus infected cells and tumors

13. Histamines are released Blood vessels dilate Histamines are released Blood vessels dilate and leak and leak

14. Macrophage

15. Temperature Response - Fever – Temperature Response - Fever – - Body temp increases in response to infection -pathogenic bacteria don’t grow well at higher temp, their enzymes denature and they die. -pathogenic bacteria don’t grow well at higher temp, their enzymes denature and they die. Proteins Proteins - Complement Proteins: kill pathogens by punching a hole in the cell membrane - 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 - Interferon: a protein released by cells infected by viruses -causes nearby cells to release an enzyme preventing the virus from reproducing

16. Fevers help eliminate pathogens

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

18. Specific Defenses Macrophage 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

19. Specific Defenses Helper T Cells Receptor proteins on helper T cells (T H ) bind to viral antigens displayed on the macrophage Receptor proteins on helper T cells (T H ) bind to viral antigens displayed on the macrophage causes macrophage to release substance to causes macrophage to release substance to activate Helper T cell.)

20. Activated helper T cells (T H ) release proteins called cytokines which activate cytotoxic T cells (T C ) and B cells Activated helper T cells (T H ) release proteins called cytokines which activate cytotoxic T cells (T C ) and B cells The activated (T C ) and B cells begin to divide The activated (T C ) and B cells begin to divide

21. Cell Mediated Response Cytotoxic T cells (T C ) punch a Cytotoxic T cells (T C ) punch a hole in the cell’s membrane hole in the cell’s membrane Your body produces many Your body produces many cytotoxic T cells (T C ) cytotoxic T cells (T C ) - each specific to a particular antigen

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

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

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

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

27. Immune Response

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

30. Plant Immune Responses:

31. 1) When bacteria come into contact with a plant cell, the plant cells detect its presence due to receptors called PRR.

32. A signalling pathway is activated. Molecular events occur and the bacterial growth is stopped. BASAL DEFENCE was activated.

33. 2) Bacteria often have a Type III secretion system which allows them to directly inject their proteins into the plant cells.

34. Some of these proteins can stop a plant cell’s Basal Defence. If this happens, then the bacteria continues growing and the plant develops a disease.

35. Plant cells have proteins which can recognize these bacterial proteins and neutralize them. When a recognition occurs, the protein essentially blocks that of the bacteria and creates a new pathway.

36. This new pathway allows the plant cell to become resistant to the attacks of the bacteria.