What is in blood?


Key parts

There are several key types of cells in blood, which are all made in bone marrowBone marrow is a soft spongy material which is inside bones. The outside of bones are hard and protective but the inside plays a different role. Bone marrow makes new blood cells.. Bone marrow is a spongy material which is inside bones. Stem cells are found in bone marrow and it is these cells that produce the different blood cells. When bone marrow does not work properly then it can affect the amount of different cell types in the blood and they may not work properly. Listed below are the most important different blood cells.

Blood cells


Red cellsRed blood cells

Red blood cells carry oxygen around the body. They collect oxygen from the lungs and supply it all around the body. When numbers become low then there is less oxygen supplied to the body and patients can feel tired and short of breath.



White cellWhite blood cells

White blood cells fight against infections. There are several different types of white blood cell which specialise in fighting against different types of infection. For example neutrophils are a type of white blood cell that fight against bacteria. Therefore when the numbers become low the body is less able to fight against infection. See neutropenic sepsis for more information.



Platelets have the job of making blood clot. For example without them when we cut ourselves then the bleeding would never stop. A sign of low platelets is bleeding more than usual which can be seen as bruising easily and badly, and frequent severe nose bleeds.




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Written by: Dr T Rider

Editor: Dr J Newman

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