Blood accounts for 7% of the human body weight, with an average
density of approximately 1060 kg/m3, very close to pure water’s
density of 1000 kg/m3. The average adult has a blood volume of
roughly 5 liters (1.3 gal), composed of plasma and several kinds
of cells (occasionally called corpuscles); these formed elements
of the blood are erythrocytes (red blood cells), leukocytes
(white blood cells), and thrombocytes (platelets). By volume,
the red blood cells constitute about 45% of whole blood, the
plasma about 54.3%, and white cells about 0.7%. One microliter
of blood contains: - 4.7 to 6.1 million (male), 4.2 to 5.4
million (female) erythrocytes: In most mammals, mature red blood
cells lack a nucleus and organelles. They contain the blood’s
hemoglobin and distribute oxygen. The red blood cells (together
with endothelial vessel cells and other cells) are also marked
by glycoproteins that define the different blood types. The
proportion of blood occupied by red blood cells is referred to
as the hematocrit, an