When blood is centrifuged, the heavier red blood cells move to one end of the tube, lighter plasma moves to the other end, and the ________ ________ that contains the white blood cells and platelets is between the two. 

Fill in the blank(s) with the appropriate word(s).

buffy coat
The small band between the packed red blood cells and the plasma in a centrifuged blood sample is the buffy coat, which contains white blood cells and platelets.