In blood serum, often known simply as serum ( from Latin serum, whey ') called, refers to those liquid portion of the blood that is obtained as the supernatant when coming from a clotted blood sample by centrifugation, the cellular components (red cells, platelets and white blood cells ) separated as sediment. This supernatant contains up to the already consumed clotting factors all naturally dissolved in the blood fluid substances. Due to the presence of bilirubin, the serum is yellowish. The blood serum thus corresponds to the blood plasma of less coagulation factors ( in particular fibrin and fibrinogen).
The physiological serum osmolarity ( isotonic ) in humans is 281-297 mosmol / l
It contains about 91 % water and 7% proteins. Protein fractions are: 62 % albumin (reserve egg white) and the various globulins as:
- 3% α1 - globulins ( lipid transport )
- 7% α2 - globulins ( iron transport, copper transport)
- 9% β - globulins ( iron transport, lipid transport )
- 17% γ - globulin ( immune system )
The remaining 2% make electrolytes, nutrients, wastes (such as urea) and hormones.
Task of the blood serum is to transport nutrients and waste products, antibodies, hormones and heat.