Blood is a specialised fluid that supplies nutrients and oxygen to the various organs muscles and tissues of the body. It also transports metabolic waste products and carbon dioxide away from them. Blood is made up of blood cells and plasma. There are three types of blood cells - red blood cells (RBCs or erythrocytes) white blood cells (WBCs or leukocytes) and platelets (thrombocytes). Plasma makes up for 55% of blood fluid while the blood cells make up the rest 45%. Plasma contains blood cells platelets proteins glucose minerals hormones and carbon dioxide. Blood tests are a very useful diagnostic