Blood serum

Blood serum is the clear, yellowish part of blood that remains after coagulation. It appears when blood is allowed to clot and all blood cells are removed. This is the portion of the plasma that is neither a blood cell (serum does not contain white or red blood cells) nor a clotting factor; it is the blood plasma not including the fibrinogens. Serum includes all proteins not used in blood clotting (coagulation) and all the electrolytes, antibodies, antigens, hormones, and any exogenous substances (e.g., drugs and microorganisms).

Composition

Blood serum is a complex mixture of substances, including proteins, enzymes, fats, and salts, that are dissolved or suspended in water. The specific composition and amount of these substances in serum vary depending on the body's needs and health.

Proteins

The most abundant proteins in blood serum are albumin and globulin. Albumin helps to maintain the body's osmotic balance and provides a source of amino acids for protein synthesis. Globulins are a group of proteins that include the immunoglobulins (antibodies), which are responsible for immune responses.

Enzymes

Various enzymes are present in blood serum, including lactate dehydrogenase, creatine kinase, and alanine transaminase. These enzymes are often used as biomarkers to assess the health of specific organs or systems.

Fats

Fats, or lipids, in blood serum are packaged into lipoproteins, which transport fats around the body. The main types of lipoproteins in the serum are low-density lipoprotein (LDL), high-density lipoprotein (HDL), and very low-density lipoprotein (VLDL).

Salts

Salts, or electrolytes, in blood serum include sodium, potassium, calcium, bicarbonate, and chloride. These electrolytes play crucial roles in a variety of physiological processes, including maintaining fluid balance, transmitting nerve impulses, and regulating muscle function.

Clinical significance

Blood serum is used in a variety of diagnostic tests, as well as in blood typing. It can be used to detect the presence of specific antibodies, which can indicate an immune response to a particular antigen. In addition, the levels of various serum components can provide information about a person's overall health, as well as the health of specific organs.

See also

• Plasma (blood)
• Serology
• Blood test