| blood crisis | The appearance of a large number of nucleated red blood cells in the peripheral blood, accompanied by reticulocytosis and occurring in "exhausted" bone marrow in pernicious anaemia and in haemolytic icterus, a suddenly appearing leukocytosis, indicating a change for the better in the course of a grave blood disease. (05 Mar 2000) |
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| blood crystals | <haematology> A substance which appears to be identical to the red-orange bile pigment bilirubin, but which is produced from haemoglobin in tissues rather than within the liver and usually when oxygen tension is low. (09 Oct 1997) |
| blood culture | <investigation, microbiology> A test which involves the incubation of a blood specimen overnight to determine if bacteria are present. (27 Sep 1997) |
| blood cyst | A cyst containing blood or resulting from the encapsulation of a haematoma. Synonym: blood cyst, haematocele, haematocyst, sanguineous cyst. (05 Mar 2000) |
| blood disk | <haematology> A discoid cell (3m diameter) found in large numbers in blood, important for blood coagulation and for haemostasis by repairing breaches (small breaks) in the walls of blood vessels. Platelet _ granules contain lysosomal enzymes, dense granules contain ADP (a potent platelet aggregating factor) and serotonin (a vasoactive amine). They also release platelet-derived growth factor which presumably contributes to later repair processes by stimulating fibroblast proliferation. Synonym: thrombocytes. (09 Oct 1997) |
| blood dust | Small refractive particles in the circulating blood, probably lipid material associated with fragmented stroma from red blood cells. Synonym: blood dust, blood motes, dust corpuscles. Origin: haemo-+ G. Konis, dust (05 Mar 2000) |
| blood dyscrasia | <haematology> A general term which is used to describe any abnormality in the blood or bone marrow's cellular components, such as low white blood cell count, low red blood cell count or low platelet count. Medications known to cause thrombocytopenia or leukopenia as a side effect include: pyrimethamine, chloramphenicol, levamisole, sulphamethoxazole and trimethoprim, sulphapyridine, sulphasalazine, antihistamines, appetite suppressants, anticonvulsants, tricyclic antidepressants, decongestants and antihistamines, benzodiazepines, chloroquine, clozapine, dapsone, glutethimide, hydroxychloroquine, isoniazid, meprobamate and aspirin, methazolamide, perphenazine and amitriptyline, phenacemide, pimozide, rifampin, thioxanthenes, trimethobenzamide, trimethoprim and trimetaphan. (27 Sep 1997) |
| blood flow velocity | A value equal to the total volume flow divided by the cross-sectional area of the vascular bed. (12 Dec 1998) |
| blood gas analysis | <investigation> 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. (27 Sep 1997) |
| blood gases | A clinical expression for the determination of the partial pressures of oxygen and carbon dioxide in blood. (05 Mar 2000) |
| blood gas monitoring, transcutaneous | The noninvasive measurement or determination of the partial pressure (tension) of oxygen and/or carbon dioxide locally in the capillaries of a tissue by the application to the skin of a special set of electrodes. These electrodes contain photoelectric sensors capable of picking up the specific wavelengths of radiation emitted by oxygenated versus reduced haemoglobin. (12 Dec 1998) |
| blood group | <haematology> An inherited feature on the surface of the red blood cell. A series of related blood groups make up a blood group system such as the ABO system or the Rh system. Erythrocytic allotypes (or phenotypes) defined by one or more cellular antigenic structural groupings under the control of allelic genes. Blood groups, especially for man, are identified by agglutinins supported by specific human or animal antisera and by lectins extracted from certain plants. See: blood group antigen. (25 Jun 1999) |
| blood group antigen | <haematology, immunology> The set of cell surface antigens found chiefly, but not solely, on blood cells. More than fifteen different blood group systems are recognised in humans. There may be naturally occurring antibodies without immunisation, especially in the case of the ABO system and matching blood groups is important for safe transfusion. In most cases the antigenic determinant resides in the carbohydrate chains of membrane glycoproteins or glycolipids. See: Rhesus, Duffy, Kell, Lewis and MN. (25 Jun 1999) |
| blood group incompatibility | A mismatch between donor and recipient blood. Antibodies present in the recipient's serum are directed against antigens in the donor product. Such a mismatch may result in a transfusion reaction in which, for example, donor blood is haemolyzed. (12 Dec 1998) |
| blood grouping | The classification of blood samples by means of laboratory tests of their agglutination reactions with respect to one or more blood groups. In general, a suspension of erythrocytes to be tested is exposed to a known specific antiserum; agglutination of the erythrocytes indicates that they possess the antigen for which the antiserum is specific. Certain antisera require special testing conditions. (05 Mar 2000) |