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Flashcards · Biology · Human Defences and Immunity

The Immune System

16 cards

  1. What is an antigen?

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

  2. What is an antibody?

    A protein made by lymphocytes that fits one specific antigen.

  3. What does a phagocyte do?

    Engulfs and digests pathogens.

  4. What do lymphocytes do?

    Make antibodies, and recognise specific antigens.

  5. Why is the immune response specific?

    An antibody fits only one antigen.

  6. How do antibodies help to destroy pathogens?

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

  7. What are memory lymphocytes?

    Lymphocytes that stay in the body after an infection.

  8. What do memory lymphocytes do?

    They respond quickly if the same pathogen enters again.

  9. What is the primary response?

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

  10. What is the secondary response?

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

  11. Why do people not usually get chickenpox twice?

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

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

    About one to two weeks.

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

    A few days.

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

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

  15. What is phagocytosis?

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

  16. Common mistake about antibodies?

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