| expired gas | Any gas that has been expired from the lungs; often used synonymously with mixed expired gas. (05 Mar 2000) |
|---|---|
| universal gas constant | <radiobiology> R = 8.314 x 10^7 ergs per degree C per mole. (09 Oct 1997) |
| landfill gas | Gas that is generated by decomposition of organic material at landfill disposal sites. Landfill gas is approximately 50 percent methane. (05 Dec 1998) |
| laughing gas | A historical term for nitrous oxide. Origin: so called because its inhalation sometimes excites a hilarious delirium preceding insensibility (05 Mar 2000) |
| lorentz gas | <radiobiology> Plasma model in which the electrons are assumed not to interact with each other, but only with ions (Z to infinity) and where the ions are assumed to remain at rest/fixed (M-i to infinity). Synonym: electron gas. (13 Jan 1998) |
| ABO blood group | <haematology> The major human blood type system which describes the oligosaccharide glycoprotein antigens found on the surface of human blood cells. According to the type of antigen present, a person may be assigned a blood type of A, B, AB or O. A second type of antigen, the Rh factor, renders a positive or negative blood type. The ABO blood group system is important because it determines who can donate blood to or accept blood from whom. Type A or AB blood will cause an immune reaction in people with type B blood and type B and AB blood will cause a reaction in people with type A blood. Conversely, type O blood has no A or B antigens, so people with type O blood are universal donors. And since AB blood already produces both antigens, people who are type AB can accept any of the other blood types without suffering an immune reaction. (04 Jul 1999) |
| Almen's test for blood | Glacial acetic acid, gum guaiac solution, and hydrogen peroxide are added to an aqueous suspension of the suspected stain; if occult blood or blood pigment is present, a blue colour develops. Synonym: guaiac test, Schonbein's test, van Deen's test. (05 Mar 2000) |
| arterial blood | Blood that is oxygenated in the lungs, found in the left chambers of the heart and in the arteries, and relatively bright red. (05 Mar 2000) |
| blood | <haematology> Considered a circulating tissue composed of a fluid portion (plasma) with suspended formed elements (red blood cells, white blood cells, platelets). Arterial blood is the means by which oxygen and nutrients are transported to tissues, venous blood is the means by which carbon dioxide and metabolic by-products are transported for excretion. (05 Jan 1998) |
| blood agar | <cell culture> An agar-based medium which hasbeen enriched with sterilised, defibinated blood (sheep, rabbit or horse). It is used for primary plating andsubculturing, especially to determine bacterial haemolysis. (09 Oct 1997) |
| blood-air barrier | The barrier between capillary blood and alveolar air comprising the alveolar epithelium and capillary endothelium with their adherent basement membranes and epithelial cell cytoplasm. Gaseous exchange occurs across this membrane. (12 Dec 1998) |
| blood albumin | <protein> The serum level of the low molecular protein albumin. Albumin, produced by the liver, plays an important role in maintaining plasma oncotic pressure. Normal serum albumin should be 3.5-5.0 grams per decilitre. Low serum albumin can be found in cases of liver disease and malnutrition. (27 Sep 1997) |
| blood-aqueous barrier | The anatomical mechanism that prevents exchange of materials between the chambers of the eye and the blood. The tight junctions of the nonpigmented epithelium of the ciliary body, the junctions of the iris tissues, and iris blood vessels constitute the blood-aqueous barrier. Lipid-soluble substances such as oxygen and carbon dioxide penetrate the barrier at a high rate. Sodium, larger water-soluble ions, proteins, and other large and medium-sized molecules are restricted. (12 Dec 1998) |
| blood bactericidal activity | Native bactericidal property of blood due to normally occurring antibacterial substances such as beta lysin, leukin, etc. (12 Dec 1998) |
| blood bank | A place, usually a separate part or division of a hospital laboratory or a separtate free-standing facility, in which blood is collected from donors, typed, separated into several components, stored, and/or prepared for transfusion to recipients. (05 Mar 2000) |