blood buffers

blood buffers

Etymology: AS, blod + ME, buffe, to cushion

a system of buffers, composed primarily of dissolved carbon dioxide and bicarbonate ions, that functions in maintaining the proper pH of the blood. See also buffer, arterial pH.

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blood

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.

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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.

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

see hematuria.

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

see hematemesis.

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.