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Flashcards · Biology

Human Defences and Immunity

80 cards from 5 lessons

  1. What is a non-specific defence?

    A defence that works against all pathogens in the same way.

  2. What is the skin made of on the outside?

    Dead cells filled with keratin.

  3. What do platelets do in a cut?

    They help the blood to clot, forming a scab.

  4. What is mucus?

    A sticky liquid that traps pathogens and dust.

  5. Which cells make mucus in the airways?

    Goblet cells.

  6. What are cilia?

    Tiny hairs on cells that beat to move mucus.

  7. Where does the mucus go from the airways?

    Up to the throat, where it is swallowed or coughed out.

  8. What does lysozyme do?

    Breaks down bacterial cell walls.

  9. Where is lysozyme found?

    In tears, saliva and mucus.

  10. What does stomach acid do?

    Kills most of the pathogens that are swallowed.

  11. What is the pH of the stomach?

    About 2.

  12. How does smoking affect the cilia?

    It paralyses and destroys them.

  13. Why do smokers get more chest infections?

    The mucus and pathogens are not moved out, so bacteria multiply in the lungs.

  14. What do friendly bacteria on the skin do?

    They compete with harmful microorganisms, and stop them settling.

  15. Is lysozyme a physical or a chemical defence?

    A chemical defence.

  16. Common mistake about cilia?

    Saying that they trap pathogens. The mucus traps pathogens, and cilia move the mucus.

  17. What is an antigen?

    A molecule on the surface of a pathogen that the immune system recognises as foreign.

  18. What is an antibody?

    A protein made by lymphocytes that fits one specific antigen.

  19. What does a phagocyte do?

    Engulfs and digests pathogens.

  20. What do lymphocytes do?

    Make antibodies, and recognise specific antigens.

  21. Why is the immune response specific?

    An antibody fits only one antigen.

  22. How do antibodies help to destroy pathogens?

    They clump pathogens together, so that phagocytes can engulf them, and neutralise toxins.

  23. What are memory lymphocytes?

    Lymphocytes that stay in the body after an infection.

  24. What do memory lymphocytes do?

    They respond quickly if the same pathogen enters again.

  25. What is the primary response?

    The slow, small response the first time a pathogen is met.

  26. What is the secondary response?

    The fast, large response the second time the same pathogen is met.

  27. Why do people not usually get chickenpox twice?

    Memory lymphocytes make a fast response, which destroys the virus.

  28. How long does the primary response take to peak?

    About one to two weeks.

  29. How long does the secondary response take to peak?

    A few days.

  30. Why does a different pathogen need a new response?

    It has different antigens, which the existing antibodies do not fit.

  31. What is phagocytosis?

    The engulfing and digestion of a pathogen by a white blood cell.

  32. Common mistake about antibodies?

    Saying that they kill pathogens directly. They bind and help to destroy them.

  33. What is a vaccine?

    A preparation of an inactive or weakened pathogen that makes the body immune.

  34. Why does a vaccine not make you ill?

    The pathogen is inactive, so it cannot reproduce or cause disease.

  35. What does a vaccine contain that triggers the immune response?

    The antigens of the pathogen.

  36. What does the body make after a vaccine?

    Antibodies and memory lymphocytes.

  37. Why is the response to a real infection faster after vaccination?

    Memory lymphocytes make a secondary response.

  38. What is a booster dose?

    An extra dose given to keep the level of memory lymphocytes high.

  39. Why does the flu vaccine change each year?

    The flu virus mutates, so its antigens change.

  40. Who developed the first vaccine?

    Edward Jenner, for smallpox.

  41. When was smallpox declared eradicated?

    1980.

  42. What is a placebo?

    A harmless substance with no effect, used for comparison in a trial.

  43. Why is a placebo used in a vaccine trial?

    To compare the effect of the vaccine with no vaccine.

  44. Give one example of a disease that has been controlled by vaccination.

    Smallpox, polio, measles or diphtheria.

  45. How is the measles vaccine different from the flu vaccine?

    Measles changes very little, so one vaccine works for life.

  46. Is a vaccine a treatment for an infection that has begun?

    No. It prevents infection in future.

  47. What is the difference between inactive and weakened pathogens?

    Inactive ones are killed, weakened ones are alive but harmless.

  48. Common mistake about vaccines?

    Saying that a vaccine gives the person the disease. It does not, because the pathogen is inactive.

  49. What is herd immunity?

    The protection of unvaccinated people, because so many others are immune that the disease cannot spread.

  50. Who depends on herd immunity?

    Babies, people with weak immune systems, and those the vaccine does not work for.

  51. What proportion must be immune for measles herd immunity?

    About 95%.

  52. What happens if vaccination rates fall below the threshold?

    Outbreaks can happen again.

  53. Give one advantage of vaccination.

    It prevents serious disease and saves lives.

  54. Give one disadvantage of vaccination.

    Mild side effects, or it does not work for everyone.

  55. What is a common side effect of vaccines?

    Soreness, redness or a slight fever.

  56. Is any vaccine 100% effective?

    No.

  57. What was the MMR scare?

    A false claim in 1998 that the MMR vaccine caused autism.

  58. What happened to MMR uptake after the scare?

    It fell, and measles outbreaks followed.

  59. Why was Wakefield's paper retracted?

    The research was flawed and unethical.

  60. Which disease has been eradicated by vaccination?

    Smallpox.

  61. Why is the cost of vaccination worthwhile?

    It is less than the cost of treating the disease.

  62. Why can the flu vaccine be less effective some years?

    The virus mutates, so the vaccine may not match.

  63. Why is a high uptake important?

    To keep the proportion immune above the herd immunity threshold.

  64. Common mistake about herd immunity?

    Saying that unvaccinated people are immune. They are protected only because the disease cannot spread to them.

  65. What are antibiotics?

    Drugs that kill bacteria or stop them from growing.

  66. Do antibiotics work on viruses?

    No.

  67. Why do antibiotics not harm human cells?

    They target structures, such as the cell wall, that human cells do not have.

  68. How does penicillin kill bacteria?

    It stops them from building their cell wall, so they burst.

  69. Who discovered penicillin?

    Alexander Fleming, in 1928.

  70. Who developed penicillin into a medicine?

    Florey and Chain.

  71. From which organism is penicillin made?

    The mould Penicillium.

  72. Why do antibiotics not work on viruses?

    Viruses have no cell wall or ribosomes of their own, and live inside host cells.

  73. How can a viral disease be prevented?

    By vaccination.

  74. What is an antiviral drug?

    A drug designed to stop a specific virus from reproducing.

  75. Why should you complete a course of antibiotics?

    To kill all of the bacteria, and not leave resistant ones.

  76. What is a broad-spectrum antibiotic?

    One that works against many types of bacteria.

  77. Why should antibiotics not be used for a cold?

    A cold is caused by a virus, and antibiotics do not work.

  78. What does a clear zone around an antibiotic disc show?

    The antibiotic stops the bacteria growing.

  79. What is the common mistake about antibiotics?

    Thinking they kill viruses.

  80. Which Nobel Prize did Fleming, Florey and Chain share?

    The 1945 Nobel Prize in Physiology or Medicine.