February 2, 2007 1:08am CST
Blood is a circulating tissue consisting of three types of cell suspended in a fluid(plasm).The most numerous cells are the red blood cells(erythrocytes),as many as five million per cubic millimetre,whose funtion is to transport oxygen. Less numerous are the white blood cells(leucocytes)of which there are several different types.Collectively they combat disease by destroying pathogenic micro-organisms which have got into the body. Finally, blood contains minute cell fragments caled platelets which play an important part in the process by which blood clots. So blood is a complex tissue whose main function is transport and defence.
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