Composition and Density of Blood

Composition and Density of Blood

As the flowing "life fluid" of the human body, blood contains numerous health‑related codes in its physicochemical properties. As one of the core physical indicators of blood, blood density serves as a key yardstick for evaluating blood concentration and component status. Its fluctuations directly reflect the physiological and pathological conditions of the body, providing important references for clinical diagnosis and health management.

Depending on the specific clinical testing application, different types of blood are required, these are classified as whole blood, plasma and serum.

The main components of blood are: plasma, red blood cells, white blood cells and platelets. Centrifugation separates whole blood into an upper layer of plasma/serum and a lower layer of blood cells, due to differences in density. Plasma accounts for approximately 55% of blood and is a mixture of water, sugars, fats, proteins, potassium salts and calcium salts. Blood cells make up the remaining 45% of blood, consisting mainly of red blood cells. The thin, greyish-white layer in the middle after centrifugation consists of platelets and white blood cells.

Whole blood: Whole blood refers to the entire volume of blood following anticoagulation.

Plasma: Plasma is the pale yellow liquid obtained after anticoagulation and centrifugation to remove blood cells.

Serum: If blood is not treated with an anticoagulant and is allowed to clot naturally, the blood will automatically coagulate under the action of a series of coagulation factors within a period of time after collection. The blood first solidifies as a whole, and after a period of time or after being centrifuged, the clotted part will separate from a clear, pale yellow liquid. This liquid is called serum.

Serum and plasma are difficult to distinguish by sight. However, during blood coagulation, a large amount of fibrinogen is consumed to form blood clots, so fibrinogen is no longer present in serum. Therefore, the key internal difference is that serum does not contain fibrinogen, while plasma does.

Density of whole blood: approximately 1.050–1.060, mainly determined by red blood cells. The higher the number of red blood cells, the higher the density of whole blood.

Density of plasma: approximately 1.025–1.030, mainly determined by the concentration of plasma proteins (albumin, globulin, etc.). The higher the protein content, the higher the density.

Density of red blood cells: approximately 1.090–1.092, positively correlated with hemoglobin content, making them the highest density component among blood cells.

To obtain blood components with a specific density, different types of separation gels must be used for precise separation.

PRP Separation Gel is used to obtain Platelet-rich plasma (PRP).

CPT Separation Gel is used to obtain mononuclear cells.

Tenghu Biol specializes in the production of high-quality serum separation gel, and also provides high-density PRP separation gel and CPT separation gel. Featuring high inertness, high temperature resistance, radiation resistance, and precise and stable density, our products are manufactured under strict parameter standards to enable accurate separation of blood components and achieve efficient isolation. They meet the medical industry’s demand for high-quality serum or plasma samples, ensuring the accuracy and reliability of test results.