Using a centrifuge, it is possible to separate blood into three main fractions.
Although we are used to thinking of blood as a simple fluid, it is in fact a suspension of cells, debris and more within a carrier fluid.
The uppermost and clear yellow layer pictured is that fluid: plasma. This is the majority of what makes up human blood - plasma constitutes about 55% of its volume - of which 95% by volume is pure water.
The central layer of opaque white is known as the buffy coat. This fraction is comprised mainly of white blood cells and platelets.
Finally, the lowermost fraction is made up of the all-important red blood cells; erythrocytes. These cells are responsible for oxygen’s transit around the body, and give blood its striking colour.