Matching Pairs Blood Basics Online version Review by Chantica Valverde 1 Leukocytes 2 PLASMA 3 Hemoglobin 4 Erythrocytes 5 Thrombocytes 6 Hematocrit White Blood cells, play a key role in the immune system and inflammatory response red blood cells, contain hemoglobin and transport oxygen to the cell is the liquid part of the blood Platelets, which are important in blood clotting is iron-based compound that binds with oxygen and transport it to the cells. is the percentage of the blood occupied by red blood cells, or erythrocytes