MEPX
Chapter 6 of 14All chapters
  1. 1How the body is organised
  2. 2Cells and tissues
  3. 3The skeleton
  4. 4Muscles
  5. 5Heart and circulation
  6. 6Blood
  7. 7Lungs and breathing
  8. 8Digestion
  9. 9Kidneys and liver
  10. 10The nervous system
  11. 11The brain
  12. 12Hormones
  13. 13Skin and senses
  14. 14The immune system

Chapter 6 of 14

Blood

What is actually in it.

Four parts

Plasma is the liquid, red cells carry oxygen, white cells fight infection and platelets clot. About 5 litres circulate in an adult.

  • Haemoglobin binds oxygen in the lungs and releases it in the tissues.
  • Iron sits at the centre of haemoglobin, which is why a shortage causes tiredness.

Blood groups

The A, B and O groups plus the rhesus factor describe markers on the red cells. They matter for transfusion because the immune system attacks markers it does not recognise.