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Blood components

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Our blood is made up of several components and each one has a special function.

Red Blood Cells

  • Red cells give blood its colour and accounts for up to 40% of its volume.
  • The main function of these cells is to carry oxygen from the lungs to all the cells of the body and remove waste products such as carbon dioxide.
  • Red cells have a shelf life of up to 42 days, stored in refrigeration.

Transfusions of red blood cells are used to treat people:

  • with severe anaemia (such as Thalassaemia Major);
  • whose red blood cells do not function adequately; and
  • who experience severe bleeding, such as accident victims and patients undergoing surgery.


  • It is the straw coloured fluid in which the red cells, white cells and platelets are suspended.
  • It contains very important nutrients and clotting factors which help to prevent or stop bleeding.
  • An average adult has approximately five litres of blood, three litres of which is plasma and 18 different products can be made from plasma donations
  • Plasma is stored frozen and has a shelf life of up to 12 months

It is the most versatile component of blood as it can be processed into a variety of products and each product can be used to treat a number of potentially life-threatening conditions including burns, creating immunisations and helping haemophiliacs.

Find out what's involved in donating plasma.


  • Platelets assist in the blood clotting process.
  • They are literally tiny plates that wedge together covering tears in the blood vessels and preventing blood from leaking into surrounding tissue.
  • Platelets are stored at room temperature and have a shelf life of only 5 days. This is why it is vital to have a constant flow of blood donations coming in.

Platelets are used primarily in the treatment of people with various cancers. Diseases such as leukaemia and medical treatments like chemotherapy can decrease a person's platelet count. If the number of platelets becomes too low spontaneous bleeding can occur. Even a small amount of bleeding can be dangerous, particularly if it occurs in the brain.

Find out what's involved in donating platelets.