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White blood cells

White blood cells

  • There are two types of white blood cells. Phagocytes and Lymphocytes. They both get rid of pathogens.
  • Phagocytes get rid of pathogens by phagocytosis:
    • Step 1: encounters foreign body or pathogen
    • Step 2: engulfs the foreign body or pathogen
    • Step 3: breaks down with enzymes
    • This is a non-specific immune response and will engulf ANY foreign body.
  • Lymphocytes, specifically B-Lymphocytes produce antibodies to fight pathogens.
    • Step 1: B-Lymphocyte encounters the pathogen.
    • Step 2: The cell produces antibodies matching the antigen on the pathogen.
    • Step 3: The antibodies fit onto the antigens and cause them to “clump”
    • Step 4: The pathogen is absorbed and digested by the white blood cells.

Primary response

  • When a foreign body first enters the system, the antigen is not recognised immediately. It takes the body a while for the lymphocytes to multiply and secret enough antibodies to destroy the pathogens.
  • Memory lymphocytes remain in the blood for a long time and remember a specific antibody.
  • The person becomes immune to that particular pathogen; their immune system can now respond quickly to an infection.

Secondary response

  • If the same pathogen enters again, the immune system will produce a quicker and stronger immune response.
  • The secondary response often gets rid of pathogens before you show any symptoms.