| blood relative | A relative of a person sharing some of the sources from which genes are derived. These will include many of the genes that operate in the blood and its constituents but no special importance attaches to the blood as a vehicle of inheritance. Spouses are not ordinarily blood relatives and when they are, the marriage is consanguineous and carries a higher risk than average of progeny homozygous by descent from ancestors in common. Such marriages are discouraged and within certain degrees of kindred may be illegal. Origin: a folk metaphor of breeding (05 Mar 2000) |
|---|---|
| blood-retinal barrier | Specialised nonfenestrated tightly-joined endothelial cells that form a transport barrier for certain substances between the retinal capillaries and the retinal tissue. (12 Dec 1998) |
| blood sedimentation | Measurement of rate of settling of erythrocytes in anticoagulated blood. (12 Dec 1998) |
| blood-shotten | Red and inflamed; suffused with blood, or having the vessels turgid with blood, as when the conjunctiva is inflamed or irritated. "His eyes were bloodshot, . . . And his hair disheveled." (Dickens) Origin: Blood + shot, p. P. Of shoot to variegate. Source: Websters Dictionary (01 Mar 1998) |
| blood smear | A sample of blood is applied to a microscope slide and then studied under the microscope. Red blood cell appearance and differential is analysed. Red blood size, shape and colour are commented on. Conditions such as hereditary spherocytosis, haemolytic anaemia, sickle cell anaemia, TTP, DIC, thalassaemia, pernicious anaemia, myelodysplasia, G6PD deficiency and lymphomas. (27 Sep 1997) |
| blood spavin | A distention of the veins in the vicinity of the tarsus in a horse, due to pressure from the swelling of bog spavin impeding the return flow of blood. (05 Mar 2000) |
| blood specimen collection | The taking of a blood sample to determine its character as a whole, to identify levels of its component cells, chemicals, gases, or other constituents, to perform pathological examination, etc. (12 Dec 1998) |
| blood spots | Haemorrhagic graafian follicles seen in ovaries of mice, caused by injection of urine of pregnant women; a positive result in the now obsolete Aschheim-Zondek test for pregnancy. (05 Mar 2000) |
| blood stains | Antigenic characteristics and DNA fingerprint patterns identified from blood stains. Their primary value is in criminal cases. (12 Dec 1998) |
| blood substitute | Any material (e.g., human plasma, serum albumin, or a solution of such substances as dextran) used for transfusion in haemorrhage and shock. (05 Mar 2000) |
| blood substitutes | Substances that can carry oxygen to and carbon dioxide away from the tissues when introduced into the blood stream. They are used to replace haemoglobin in severe haemorrhage and also to perfuse isolated organs. The best known are perfluorocarbon emulsions and various haemoglobin solutions. (12 Dec 1998) |
| blood sugar, high | Elevated levels of blood glucose (hyperglycaemia) can be found in a number of conditions. The hyperglycaemia leads to spillage of glucose into the urine, hence the term sweet urine. (Diabetes mellitus means sweet urine. ) (12 Dec 1998) |
| blood sugar, low | The sugar here is glucose. Low blood glucose constitutes hypoglycaemia. Hypoglycaemia is only significant when it is associated with symptoms. It has many causes including drugs, liver disease, surgical absence of the stomach, pre-diabetes, and rare tumours that release excess insulin. (12 Dec 1998) |
| blood-testis barrier | The membrane in the testis that separates sperm from the bloodstream. (09 Oct 1997) |
| blood-thinner | <haematology, pharmacology> Any substance that prevents blood clotting. Those drugs administered for prophylaxis or treatment of thromboembolic disorders are heparin, which inactivates thrombin and several other clotting factors and which must be administered parenterally and the oral anticoagulants (warfarin, dicumarol and congeners) which inhibit the hepatic synthesis of vitamin K dependent clotting factors. Anticoagulant solutions used for the preservation of stored whole blood and blood fractions are acid citrate dextrose (ACD), citrate phosphate dextrose (CPD), citrate phosphate dextrose adenine (cPDA 1) and heparin. Anticoagulants used to prevent clotting of blood specimens for laboratory analysis are heparin and several substances that make calcium ions unavailable to the clotting process, including EDTA (ethylenediaminetetraacetic acid), citrate, oxalate and fluoride. (18 Nov 1997) |