Blood
The blood has two main components—the blood cells (or formed elements)—and the plasma, the fluid phase of the blood.
These two components can be separated from one another by centrifugation at low speed.
A tube of blood after centrifugation (center) has nearly half of its volume represented by erythrocytes in the bottom half of the tube, a volume called the hematocrit. Red cells are dense and collect in the bottom of the tube, whereas white cells and platelets are of intermediate density and tend to collect at the interface between the red cells and the plasma in a thin gray-white layer referred to as the buffy coat.1
Below are the concentration ranges of erythrocytes, platelets, and leukocytes in normal blood, along with the differential count or percent range for each type of leukocyte represented in the buffy coat.1
Adult men have about five liters of blood, whereas women average closer to four.
