(graf′ē-ăn, grof′ē-ăn) [Regnier de Graaf, Dutch physician and anatomist, 1641–1673] A mature vesicular follicle of the ovary. Beginning with puberty and continuing until menopause (except during pregnancy), a graafian follicle develops at approx. monthly intervals. Each follicle contains a nearly mature ovum (an oocyte) that, on rupture of the follicle, is discharged from the ovary, a process called ovulation. Ovulation usually occurs 12 to 16 days before the first day of the next menstrual period. Within the ruptured graafian follicle, the corpus luteum develops. Both the follicle and the corpus luteum are endocrine glands, the former secreting estrogens, and the latter, estrogen and progesterone. SEE: ovulation; ovum for illus.
(grăs′ĭl) [L. gracilis, slender] Slender; slight.
(gras′ĭ-lĭs) [L. gracilis, slender] SEE: gracilis muscle.
(grād) [Fr. grade, office, fr. L. gradus, step, degree] 1. A standard measurement or assessment. 2. A slope or incline.
(grād′ē-ĕnt) [L. gradi, to step, walk] 1. The difference between two quantities. 2. The graphical representation of the difference between two quantities.
alveolar/arterial g. ABBR: A/a gradient. The difference between the calculated oxygen pressure available in the alveolus and the arterial oxygen tension. It measures the efficiency of gas exchange. SYN: respiratory index.
The formula for measuring the gradient is known as the partial pressure of oxygen dissolved in arterial blood and is shown below.
authority g. The perceived difference in status between different members of an organization. It is a barrier to effective communication and a potential source of interpersonal resentment and organizational error. Authority gradients exist in health care organizations when one member of a team, e.g., a medical assistant, feels he or she cannot broach an important safety issue with another member on a higher level.
average g. In sensitometry, a measure of the contrast of the film or film-screen system by determination of the slope of the sensitometric curve.
axial g. A gradient of physiological or metabolic activity exhibited by embryos and many adult animals. The principal gradient follows the main axis of the body, being highest at the anterior end and lowest at the posterior end.
concentration g. The difference in the amounts of a substance on either side of a membrane or in two areas of a biological system. Substances diffuse down a concentration gradient, from the area of higher concentration to lower concentration.
hepatic venous pressure g. The venous pressure differences in the ...