| blood gases | A clinical expression for the determination of the partial pressures of oxygen and carbon dioxide in blood. (05 Mar 2000) |
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| gases | The vapor state of matter; nonelastic fluids in which the molecules are in free movement and their mean positions far apart. Gases tend to expand indefinitely, to diffuse and mix readily with other gases, to have definite relations of volume, temperature, and pressure, and to condense or liquefy at low temperatures or under sufficient pressure. (12 Dec 1998) |
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| greenhouse gases | Gases that trap the heat of the sun in the Earth's atmosphere, producing the greenhouse effect. The two major greenhouse gases are water vapour and carbon dioxide. Other greenhouse gases include methane, ozone, chlorofluorocarbons, and nitrous oxide. (05 Dec 1998) |
| combustion gases | The gases released from a combustion process. (05 Dec 1998) |
| noble gases | Gases which are members of the zero group of the periodic system. These gases generally do not react chemically. (12 Dec 1998) |
| inert gases | Gases which are members of the zero group of the periodic system. These gases generally do not react chemically. (12 Dec 1998) |
| tear gases | Gases that irritate the eyes, throat, or skin. Severe lacrimation develops upon irritation of the eyes. (12 Dec 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) |
| arterial blood gas | A test which analyses arterial blood for oxygen, carbon dioxide and bicarbonate content in addition to blood pH. Used to test the effectiveness of respiration. Acronym: ABG (17 Oct 1997) |
| 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) |