Question: A nursing student is studying for an examination on the immune and hematologic systems. Which response given by the student would indicate to the nursing instructor that the student has a good understanding of blood component therapy? The registered nurse (RN) has 2 hours after receiving blood from the blood bank to start the transfusion of packed red blood cells (PRBCs). Plasma is frozen immediately and lasts up to one year before being discarded. Platelets cannot withstand warm temperatures, so they must be frozen. A single unit of whole blood contains 50 mL of blood and 450 mL of anticoagulant.