Components of Blood - Topic 1 - Edexcel AS 2.0 / 5 based on 1 rating ? BiologyBiological molecules, organic chemistry and biochemistryASEdexcel Created by: CharlottteCreated on: 06-01-13 16:31 Plasma Main component of blood Largely made of water Contains wide range of dissolved substances to be transported around body Contains fibrinogen - soluble substance used in blood clotting 1 of 4 Erythrocytes - RED blood cells Bioconcave discs Approx. 5 million per mm3 of blood Contain haemoglobin - red pigment which carries oxygen (and hence no nucleus) Formed in red bone marrow of short bones - eg. ribs Limited life of around 120 days 2 of 4 Leucocytes - WHITE blood cells Much larger than red blood cells Can squeeze through tiny blood vessels as they can change their shape Approx. 4000-11000 per mm3 of blood Contain a nucleaus and colourless cytoplasm Several types Most formed in white bone marrow of long bones - eg. humerus and femur However, lymphocytes are formed in lymph glands and spleen Main function - defend body against infection 3 of 4 Platelets Tiny fragments of large cells known as megakaryocytes found in bone marrow About 150 000 - 400 000 platelets per mm3 of blood Involved in clotting of the blood 4 of 4
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