<Li> Messenger functions, including the transport of hormones and the signaling of tissue damage </Li> <Li> Regulation of core body temperature </Li> <P> Blood accounts for 7% of the human body weight, with an average density around 1060 kg / m, very close to pure water's density of 1000 kg / m . The average adult has a blood volume of roughly 5 litres (11 US pt), which is composed of plasma and several kinds of cells . These blood cells (which are also called corpuscles or "formed elements") consist of erythrocytes (red blood cells, RBCs), 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% . </P> <P> Whole blood (plasma and cells) exhibits non-Newtonian fluid dynamics . If all human hemoglobin were free in the plasma rather than being contained in RBCs, the circulatory fluid would be too viscous for the cardiovascular system to function effectively . </P>

The formed elements in the blood are mostly