READ MORE ON THIS TOPIC Blood is made up of a couple of components, which include purple blood cells, white blood cells, platelets, and plasma. Blood: Laboratory exam of blood Physicians rely upon laboratory evaluation to achieve measurements of many components of the blood, records useful or vital for the detection and popularity of disorder. Blood is composed of plasma and blood cells. The blood cells-erythrocytes (red cells), leukocytes (white cells), and thrombocytes (platelets)-are suspended within the plasma with different particulate count number. Plasma is a clear straw-colored fluid that makes up more than 1/2 the quantity of blood.