Human blood is composed of several different cell types: Red blood cells, white blood cells, and platelets. Another word for blood cell is haematopoietic cell or hemocyte. Together, these blood cells comprise a total of 45%. The remaining volume is composed of the blood plasma.

Figure 1: Blood cells. Neutrophil, monocyte, eosinophil, basophil, and lymphocyte are types white blood cells.