| 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) |
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| 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) |
| blood banks | Centres for collecting, characterizing and storing human blood. (12 Dec 1998) |
| blood blister | <dermatology> A collection of blood within a skin blister that results from minor skin trauma such as a pinch or crushing injury. (27 Sep 1997) |
| blood-boltered | Having the hair matted with clotted blood. "The blood-boltered Banquo smiles upon me." (Shak) Origin: Blood + Prov. E. Bolter to mat in tufts. Cf. Balter. Source: Websters Dictionary (01 Mar 1998) |
| blood-borne pathogens | Infectious organisms in the blood, of which the predominant medical interest is their contamination of blood-soiled linens, towels, gowns, bandages, other items from individuals in risk categories, needles and other sharp objects, and medical and dental waste, all of which health workers are exposed to. This concept is differentiated from the clinical conditions of bacteraemia, viraemia, and fungaemia where the organism is present in the blood of a patient as the result of a natural infectious process. (12 Dec 1998) |
| blood-brain barrier | <pharmacology, physiology> A protective barrier formed by the blood vessels and glia of the brain. It prevents some substances in the blood from entering brain tissue. The blood vessels of the brain (and the retina) are much more impermeable to large molecules (like antibodies) than blood vessels elsewhere in the body. This has important implications for the ability of the organism to mount an immune response in these tissues, although the basis for the difference in endothelial permeability is not well understood. (16 Dec 1997) |
| blood calculus | An angiolith or concretion of coagulated blood. Synonym: hemic calculus. (05 Mar 2000) |
| blood capillary | A vessel whose wall consists of endothelium and its basement membrane; its diameter, when the capillary is open, is about 8 um; with the electron microscope, fenestrated capillary's and continuous capillary's are distinguished. (05 Mar 2000) |
| blood cast | A cast usually formed in renal tubules, but may occur in bronchioles; consists of inspissated material that includes various elements of blood (i.e., erythrocytes, leukocytes, fibrin, and so on), resulting from bleeding into the glomerulus or tubule, or into the alveolus or bronchiole. (05 Mar 2000) |
| blood catecholamine | <investigation> The measurement of noradrenaline and adrenaline in the blood. Often these same catecholamines can be measured in the urine. Elevations may be seen in pheochromocytoma or neuroblastoma. Normal blood levels of adrenaline should be: 20 ng/ml and normal blood levels of noradrenaline should be 60 ng/ml. (05 Jan 1998) |
| blood cell | <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 cell count | A count of the number of leukocytes and erythrocytes per unit volume in a sample of venous blood. A complete blood count (cbc) also includes measurement of the haemoglobin, haematocrit, and erythrocyte indices. (12 Dec 1998) |
| blood-cerebrospinal fluid barrier | A barrier located at the tight junctions which surround and connect the cuboidal epithelial cells on the surface of the choroid plexus; capillaries and connective tissue stroma of the choroid do not represent a barrier to protein tracers or dyes. (05 Mar 2000) |