| blood clot | <haematology> The conversion of blood from a liquid form to solid through the process of coagulation. A thrombus is a clot which forms inside of a blood vessel. If that clot moves inside the vessel it is referred to as an embolus (embolism). The presence of atherosclerotic plaque lining blood vessel walls is a significant stimulus for clot formation. (27 Sep 1997) |
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| blood clotting factor | <haematology> Any of a number of different protein factors which, when acting together, can form a blood clot shortly after platelets have broken at the site of the wound. The factors have Roman numeral names, like VII, VIII, IX, X, XI, and XIII. Defects in the genes which code for any of these factors result in genetic diseases like haemophilia, which results from a defect in the gene for factor VIII or IX. (09 Oct 1997) |
| blood coagulation | The sequential process by which the multiple coagulation factors of the blood interact, ultimately resulting in the formation of an insoluble fibrin clot; it may be divided into three stages: stage 1, the formation of intrinsic and extrinsic prothrombin converting principle; stage 2, the formation of thrombin; stage 3, the formation of stable fibrin polymers. (12 Dec 1998) |
| blood coagulation factor inhibitors | Substances, usually endogenous, that act as inhibitors of blood coagulation. They may affect one or multiple enzymes throughout the process. As a group, they also inhibit enzymes involved in processes other than blood coagulation, such as those from the complement system, fibrinolytic enzyme system, blood cells, and bacteria. (12 Dec 1998) |
| blood coagulation factors | Endogenous substances, usually proteins, that participate in the blood coagulation process. (12 Dec 1998) |
| blood coagulation tests | Laboratory tests for evaluating the individual's clotting mechanism. (12 Dec 1998) |
| blood component removal | Any procedure in which blood is withdrawn from a donor, a portion is separated and retained and the remainder is returned to the donor. (12 Dec 1998) |
| blood component transfusion | The transfer of blood components such as erythrocytes, leukocytes, platelets, and plasma from a donor to a recipient or back to the donor. This process differs from the procedures undertaken in plasmapheresis and types of cytapheresis (plateletpheresis and leukapheresis) where, following the removal of plasma or the specific cell components, the remainder is transfused back to the donor. (12 Dec 1998) |
| blood corpuscle | <haematology> There are three main types of cell in the blood stream. The red cell, which carries oxygen, the white cell, which fights infections and the platelet, which helps prevent bleeding. The correct balance between each cell type must be maintained for the body to remain healthy. (13 Nov 1997) |
| blood count | <haematology, investigation> The determination of the proper number of red blood cells, white blood cells and platelets are present in the patients blood. Acronym: FBC (16 Dec 1997) |
| 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) |
| 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) |
| red blood cell count | A normal value is 4.6-6.2 million RBC's per cubic millimetre of blood. This number can increase in cases of dehydration (fluid loss) or severe lung disease. Interestingly, red blood cell counts are much higher in those who live at high altitude, because of the increased demand for oxygen carrying capacity. (27 Sep 1997) |
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| red blood cell indices | Laboratory measurements of red blood cell volume, size and haemoglobin concentration. These values are used to point to the specific cause for anaemia (iron deficiency, B12 deficiency, etc.) (27 Sep 1997) |
| CDE blood group | See Rh blood group, Blood Groups appendix. (05 Mar 2000) |
| renal blood flow, effective | The amount of blood flowing to the parts of the kidney that are involved with the production of constituents of urine. It is that portion of the total renal blood flow that perfuses functional renal tissue (e.g., the glomeruli). It should be differentiated from renal plasma flow, effective which is based on the amount of plasma rather than on total renal blood. (12 Dec 1998) |
| p blood-group system | A blood group related to the abo, lewis and I systems. at least five different erythrocyte antigens are possible, some very rare, others almost universal. Multiple alleles are involved in this blood group. (12 Dec 1998) |
| retinal blood vessels | The blood vasculature of the retina, including the branches and tributaries of the central retinal artery and vein, respectively, and the vascular circle of the optic nerve. Synonym: vasa sanguinea retinae. (05 Mar 2000) |
| percutaneous umbilical blood sampling | See: PUBS. (12 Dec 1998) |
| Rhesus blood group | <haematology> Human blood group system with allelic red cell antigens C, D and E. The D antigen is the strongest. Red cells from a Rhesus positive foetus cross the placenta and can sensitise a Rehesus negative mother, expecially at parturition. The mother's antibody may then, in a subsequent pregnancy, cause haemolytic disease of the newborn if the foetus is Rhesus positive. The disease can be prevented by giving antiD IgG during the first 72 hours after parturition to mop up D red cells in the maternal circulation. 1st ed (18 Nov 1997) |
| rh-hr blood-group system | Erythrocyte isoantigens of the rh (rhesus) blood group system, the most complex of all human blood groups, because the genes differ by determining a different number of the over thirty antigens thus far described and do so with remarkably different quality. The major antigen rh or d is the most common cause of erythroblastosis foetalis. (12 Dec 1998) |
| peripheral blood stem cell transplantation | A procedure that is similar to bone marrow transplantation. Doctors remove healthy immature cells (stem cells) from a patient's blood and store them before the patient receives high-dose chemotherapy and possibly radiation therapy to destroy the leukaemia cells. The stem cells are then returned to the patient, where they can produce new blood cells to replace cells destroyed by the treatment. (12 Dec 1998) |
| Pfeiffer's blood agar | Solid agar with a few drops of human blood smeared on the surface. (05 Mar 2000) |
| Romanowsky's blood stain | <technique> Prototype of the eosin-methylene blue stain's for blood smears, using aqueous solutions made of a mixture of methylene blue (saturated) and eosin. Romanowsky-type stain's depend for their action on compounds formed by interaction of methylene blue and eosin; most are of no value if water is present in the alcohol because neutral dyes become precipitated. (05 Mar 2000) |
| MN blood group antigens | <haematology, immunology> A pair of blood group antigens governed by genes that segregate independently of the ABO locus. The alleles are codominant and there are three types MM, NN and MN. Glycophorin has M or N activity and this is associated with oligosaccharides attached to the amino terminal portion of the molecule. M type glycophorin differs from N type in amino acid residues 1 and 5, although the antigenic determinants are associated with the carbohydrate side chains. (18 Nov 1997) |
| MNSs blood group | See Blood Groups appendix. (05 Mar 2000) |
| mnss blood-group system | A system of universal human blood group isoantigens with many associated subgroups. The m and n traits are codominant and the s and s traits are probably very closely linked alleles, including the u antigen. This system is most frequently used in paternity studies. (12 Dec 1998) |