blood osmolality

Also found in: Dictionary, Thesaurus, Legal, Encyclopedia.
Related to blood osmolality: osmolar gap

blood osmolality

Etymology: AS, blod + Gk, ōsmos, impulsion
the osmotic pressure of blood. It measures the amount of solute concentration per unit of total volume of a particular solution. The normal values in serum are 280 to 295 mOsm/L. See also osmolality.


the red fluid that circulates through the heart, arteries, capillaries and veins carrying nutrients and oxygen to the body tissues and metabolites away from them. It consists of a yellow, protein-rich fluid, the plasma, and the cellular elements including leukocytes, erythrocytes and platelets. It has a high viscosity and osmotic tension and clots on exposure to air and to damaged tissue. It has an essential role in the maintenance of fluid balance.
In an emergency, blood cells and antibodies carried in the blood are brought to a point of infection, or blood-clotting substances are carried to a break in a blood vessel. The blood carries hormones from the endocrine glands to the organs they influence. And it helps in the regulation of body temperature by carrying excess heat from the interior of the body to the surface layers of the skin, where the heat is dissipated to the surrounding air. See also bloody.

arterial blood
oxygenated blood in the arterial side of the circulation between the cardiac ventricles and the capillaries.
blood buffers
substances which enable the blood to absorb much acidity without significant change in pH. The principal ones are the bicarbonate and hemoglobin buffers.
central blood
blood from the pulmonary venous system; sometimes applied to splanchnic blood, or blood obtained from chambers of the heart or from bone marrow.
central venous blood
unoxygenated blood collected centrally from the right atrium or venae cavae.
citrated blood
blood treated with sodium citrate to prevent its coagulation.
blood clotting cascade
see coagulation cascade.
cord blood
that contained in the umbilical vessels at the time of delivery of the fetus.
defibrinated blood
whole blood from which fibrin has been separated during the clotting process.
extracorporeal blood flow
see extracorporeal circulation.
blood in feces
see melena.
blood islet
aggregates of splanchnic mesoderm on the surface of the yolk sac and allantois; the first blood cells in the embryo.
blood lactate
this estimation has good predictive value in a number of diseases, e.g. intestinal obstruction in horses.
blood in milk
appears as clots or as diffuse red tint. Common only in recently calved cows or after trauma. Of no disease significance but renders the milk unsuitable for sale.
Enlarge picture
Blood clots in pink milk. By permission from Blowey RW, Weaver AD, Diseases and Disorders of Cattle, Mosby, 1997
occult blood
that present in such small amounts as to be detectable only by chemical tests or by spectroscopic or microscopic examination. See also occult blood test.
blood osmolality
see serum osmolality.
peripheral blood
that obtained from the circulation remote from the heart; the blood in the systemic circulation.
selective blood agar
see blood agar.
shunted blood
blood which is not oxygenated in the lung because it passes through unaerated tissue.
sludged blood
blood in which the red cells have become aggregated into clumps and is most marked where the flow rate is slowest, i.e. in the capillaries.
blood solutes
see individual elements, metabolic products, hormones and the like.
stiff blood agar
see blood agar.
blood substitutes
synthetic substances that may be used in place of blood or its components include dextran, hydroxyethyl starch, polyvinylpyrrolidone, gelatin and perfluorocarbon.
blood urea nitrogen (BUN)
see urea nitrogen.
blood urea test
see urea nitrogen.
blood in urine
venous blood
blood which has passed through the capillaries and discharged its oxygen load to tissues and relieved the tissue load of carbon dioxide by absorbing it, and is on its way to the lungs to reverse these processes; is dark red in color due to the high concentration of reduced hemoglobin.
blood volume expanders
are used in the treatment of shock to restore tissue perfusion. Various fluids including whole blood, plasma, crystalloids and colloids may be used.
blood in vomitus
whole blood
that from which none of the elements has been removed, especially that drawn from a selected donor under aseptic conditions, containing citrate ion or heparin, and used as a blood replenisher.