THE COMPOSITION OF BLOOD

   Blood donors generally give whole blood. In many cases, though, they donate plasma. while some Countries transfuse whole blood, more commonly, blood is separated into its primary components before it is tested and used in transfusion medicine. Note the four primary component, their functions, and the percentage of  total blood volume each represents.   

PLASMA constitutes between 52 and 62 percent of whole blood. It is straw- coloured fluid in which blood cells, proteins, and other substances are suspended and transported. Water constitute 91.5 percent of plasma. Protein from which plasma fractions are derived, constitute 7 percent of the plasma (including albumins which make up about 4 percent of the plasma; globulins, about 3 percent, and fibrinogen, less than 1 percent). The remaining 1.5 percent of plasma is made up of other substances, such a nutrients, hormones, respiratory gases, electrolytes, vitamins, and nitrogenous wastes.

WHITE BLOOD CELLS(Leukocytes) constitute less than 1 percent of whole blood. These attack and destroy potentially harmful foreign matter.

PLATELETS (Thrombocytes) Constitutes less than 1 percent of the whole blood. These form clots, blocking blood from exiting wounds.

RED BLOOD CELLS (Erythrocytes) Constitutes between 38 and 48 percent of whole blood. These cells keep tissue alive by bringing oxygen to it and taking cabondioxide away.