Blood, organ and tissue


Blood is the fluid that transports oxygen and nutrients around the body. An average adult has just under 5 litres of blood circulating around their body.

Blood is made up of the following four major components:

  • red blood cells – their main role is to transport oxygen
  • white blood cells – the cells of the immune system which defend the body against infections
  • platelets – important for blood clotting and tissue repair
  • plasma – the liquid part of the blood which carries the blood cells and other substances around the body.

Blood donations

Blood donations collected are separated into components so that they can be supplied to meet clinical need. For more information on fresh blood products and their use, please visit the National Blood Authority’s website.


Plasma is also used to manufacture other products. Proteins isolated from plasma by fractionation processes and can be made into products to treat specific diseases. Some blood products are manufactured from non-human components using genetic engineering. These are called recombinant products and are alternatives to some fractionated products.

Organs and tissues

Human body tissue is another way of describing how our cells are grouped together in a highly organised manner according to specific structure and function. These groupings of cells form tissues, which then make up organs and various parts of the body. See the organ and tissue donation page for more information, including the organs and tissues which can be donated. 

Further information on blood, organ and tissue 

Key information has been prepared to assist consumers who have contact with the health system regarding blood transfusions, iron disorders and organ and tissue donation. See the below pages for more information: