GCSE Biology (AQA)

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White Blood Cells

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Organisation Animal Tissues, Organs and Organ Systems

White Blood Cells

1:34 Blood
Spec 4.2.2.3
Previous Red Blood Cells Next Platelets
  • White blood cells are part of the immune system.
  • They help fight off invading microorganisms and viruses.
  • A diagram shows a white blood cell.
  • White blood cells protect our bodies from infection.
  • There are two types of white blood cells that target pathogens: phagocytes and lymphocytes.
  • Phagocytes engulf and digest pathogens.
  • Lymphocytes produce antibodies that target pathogens.
  • More details on phagocytes and lymphocytes will be covered elsewhere in the course.
  • Unlike red blood cells, white blood cells have a nucleus.
  • White blood cells make up a tiny proportion of the blood.
  • When blood is centrifuged, the plasma appears as a straw-colored liquid at the top, red blood cells at the bottom, and white blood cells and platelets form a thin blue layer in the middle.
  • White blood cells and platelets make up less than 1% of the blood.
  • There are approximately 7.5 million white blood cells in a cubic centimeter of blood.
  • The specific numbers of white blood cells are not required to be memorized but are provided for appreciation of their abundance in the body.

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