| vascular circle | The circle around the mouth formed by the inferior and superior labial arteries. Synonym: areolar venous plexus. (05 Mar 2000) |
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| vascular circle of optic nerve | <anatomy, nerve> A network of branches of the short ciliary arteries on the sclera around the point of entrance of the optic nerve. Synonym: circulus vasculosus nervi optici, circulus arteriosus halleri, circulus zinnii, Haller's circle, Zinn's corona, Zinn's vascular circle. (05 Mar 2000) |
| Ramsden circle | <microscopy> The circular spot of light formed at that distance above the eyepiece where the chief image forming rays cross, the back focal plane of the eyepiece. The objective back focal plane is in conjugate focus in this same plane. In visual microscopy, the point where the pupil of the eye is placed. (05 Aug 1998) |
| venous circle of mammary gland | areolar venous plexus |
| parenteral absorption | Absorption by any route other than the alimentary tract. (05 Mar 2000) |
| mass energy absorption coefficient | <physics> The mass energy absorption coefficient, uen/p of a material for uncharged ionising particles is the product of the mass energy transfer coefficient, utr/p and (1 - g) where g is the fraction of the energy of secondary charged particles that is lost to bremsstrahlung in the material. (16 Dec 1997) |
| Carus' circle | An imaginary curved line obtained from a mathematical formula, supposed to indicate the outlet of the pelvic canal. Synonym: Carus' circle. (05 Mar 2000) |
| vicious circle | The mutually accelerating action of two independent diseases or phenomena, or of a primary and secondary affection, the passage of food, after a gastroenterostomy, from the artificial opening through the intestinal loop by antiperistaltic action and back into the stomach again by the pyloric orifice, or the reverse. (05 Mar 2000) |
| pathologic absorption | Parenteral absorption of any excremental or pathologic material into the bloodstream, e.g., pus, urine, bile, etc. (05 Mar 2000) |
| vitamin B12 absorption test | <investigation> This test measures the amount of vitamin B12 in the urine after ingesting a dose of B12. This test evaluates vitamin B12 absorption. The cells in the stomach produce a substance known as intrinsic factor. This substance combines with B12 to allow absorption in the distal ileum. The patient is given a small dose of radioactive B12 which can then be detected in the patients urine. Pernicious anaemia is the clinical result of B12 deficiency. Conditions that can result in an abnormal Schilling test include: deficiency of intrinsic factor, malabsorption or the development of an antibody to intrinsic factor. The Schilling test can be performed with or without administration of intrinsic factor to determine what the underlying cause for pernicious anaemia. Laxative use, renal insufficiency and hypothyroidism can all interfere with the results of this test. (27 Sep 1997) |
| cerebral arterial circle | The roughly pentagonally shaped circle of vessels on the ventral aspect of the brain in the area of the optic chiasm, hypothalamus, and interpeduncular fossa. See: circle of Willis. (05 Mar 2000) |
| percutaneous absorption | The absorption of drugs, allergens, and other substances through unbroken skin. Synonym: cutaneous absorption. (05 Mar 2000) |
| greater arterial circle of iris | An arterial circle at the ciliary border of the iris. Synonym: circulus arteriosus iridis major. (05 Mar 2000) |
| Ridley's circle | Dural venous formation which surrounds the hypophysis, composed of right and left cavernous sinuses and the intercavernous sinuses. Synonym: circulus venosus ridleyi, Ridley's circle. A venous sinus at the periphery of the placenta. Synonym: sinus venosus sclerae. (05 Mar 2000) |
| rolling circle | A mechanism for the replication of circular DNA. (05 Mar 2000) |