| area pellucida | The translucent central part of the blastoderm of birds and reptiles. (05 Mar 2000) |
|---|---|
| area postrema | A small, elevated area in the lateral wall of the inferior recess of the fourth ventricle; one of the few loci in the brain where the blood-brain barrier is lacking; a chemoreceptor area associated with vomiting. (05 Mar 2000) |
| area subcallosa | A slender vertical whitish band immediately anterior to the lamina terminalis and anterior commissure; contrary to its name, it is not a cortical convolution but is the ventral continuation of the transparent septum. Synonym: area subcallosa, gyrus paraterminalis, gyrus subcallosus, pedunculus corporis callosi, corpus paraterminale, paraterminal body, paraterminal gyrus, peduncle of corpus callosum, precommissural septal area, subcallosal area, Zuckerkandl's convolution. (05 Mar 2000) |
| area under curve | A statistical means of summarizing information from a series of measurements on one individual. It is frequently used in clinical pharmacology where the auc from serum levels can be interpreted as the total uptake of whatever has been administered. As a plot of the concentration of a drug against time, after a single dose of medicine, producing a standard shape curve, it is a means of comparing the bioavailability of the same drug made by different companies. (12 Dec 1998) |
| area under the curve | A measure of how much of a drug reaches the bloodstream in a set period of time, usually 24 hours. AUC is calculated by plotting drug blood concentration at various times during a 24-hour or longer period and then measuring the area under the curve between 0 and 24 hours as shown in the figure to the right. (09 Oct 1997) |
| area vasculosa | The part of the area opaca of the embryonic blastoderm of the chick, where the first blood vessels appear. (05 Mar 2000) |
| area vestibularis inferior | The area of the fundus of the internal acoustic meatus inferior to the transverse crest through which the interior portion of the vestibular (saccular) nerve passes. Synonym: area vestibularis inferior. (05 Mar 2000) |
| area vestibularis superior | The area in the fundus of the internal acoustic meatus superior to the transverse crest through which the superior part of the vestibular nerve passes to reach the macula utriculus and the ampullae of the anterior and lateral saemicircular ducts. Synonym: area vestibularis superior. (05 Mar 2000) |
| areal cover | <botany, ecology> A measure of dominance that defines the degree to which above ground portions of plants cover the ground surface, it is possible for the total areal cover for all strata combined in a community or for single stratum to exceed 100 percent because: most plant communities consist of two or more vegetative strata. Areal cover is estimated by vegetative layer, and foliage within a single layer may overlap. (09 Oct 1997) |
| areata | Occurring in patches or circumscribed areas. Origin: L. (05 Mar 2000) |
| areca | <botany> A genus of palms, one species of which produces the areca nut, or betel nut, which is chewed in India with the leaf of the Piper Betle and lime. Origin: Canarese adiki: cf. Pg. & Sp. Areca. Source: Websters Dictionary (01 Mar 1998) |
| arecaidine | 1,2,5,6-tetrahydro-1-methylnicotinic acid;a crystalline alkaloid resembling betaine, derived from the betel nut. Synonym: arecaine. (05 Mar 2000) |
| arecaine | 1,2,5,6-tetrahydro-1-methylnicotinic acid;a crystalline alkaloid resembling betaine, derived from the betel nut. Synonym: arecaine. (05 Mar 2000) |
| arecoline | <chemical> An alkaloid obtained from the betel nut (areca catechu), fruit of a palm tree. It is an agonist at both muscarinic and nicotinic acetycholine receptors. It is used in the form of various salts as a ganglionic stimulant, a parasympathomimetic, and a vermifuge, especially in veterinary practice. It has been used as a euphoriant in the pacific islands. Pharmacological action: ganglionic stimulants, muscarinic agonist, nicotinic agonists, parasympathomimetic. Chemical name: 3-Pyridinecarboxylic acid, 1,2,5,6-tetrahydro-1-methyl-, methyl ester (12 Dec 1998) |
| areflexia | Absence of reflexes. Detrusor areflexia, a failure of the detrusor muscle to have a reflex contraction even though the bladder has reached or exceeded its capacity. (05 Mar 2000) |