center (sen´ter)

1. The middle point of a body; loosely, the interior of a body. A center of any kind, especially an anatomical center. 2. A group of nerve cells governing a specific function.centrum [NA]; [L. centrum; G. kentron]
active c. the part of a macromolecule at which a substrate or ligand, upon binding, produces biological activity; for an enzyme, this is the catalytic c., the site on an enzyme that catalyzes the reaction.
anospinal c. the c. in the spinal cord that controls the contraction of the anal sphincter.
Broca's c. the posterior part of the inferior frontal gyrus of the left or dominant hemisphere, corresponding approximately to Brodmann's area 44; Broca identified this region as an essential component of the motor mechanisms governing articulated speech.Broca's area, Broca's field, motor speech c;
Budge's c. ciliospinal c
catalytic c. See active c.
cell c. cytocentrum
chondrification c. a site of earliest cartilage formation in the body.
ciliospinal c. the preganglionic motor neurons in the first thoracic segment of the spinal cord which give rise to the sympathetic innervation of the dilator muscle of the eye's pupil.Budge's c;
dentary c. a specific ossification c. of the mandible that gives rise to the lower border of its outer plate.
diaphysial c. primary c. of ossification in the shaft of a long bone.
epiotic c. the c. of ossification of the petrous part of the temporal bone that appears posterior to the posterior semicircular canal.
expiratory c. the region of the medulla oblongata that is electrically active during expiration and where electrical stimulation produces sustained expiration.
feeding c. a region of the lateral zone of the hypothalamus, electrical stimulation of which in the rat elicits uninterrupted eating; destruction of the region causes long-lasting anorexia.
germinal c. of Flemming the lightly staining c. in a lymphatic nodule in which the predominant cells are large lymphocytes and macrophages.reaction c;
inspiratory c. the region of the medulla oblongata that is electrically active during inspiration and where electrical stimulation produces sustained inspiration.
Kerckring's c. an occasional independent ossification c. in the occipital bone; it appears in the posterior margin of the foramen magnum at about the sixteenth week of gestation.Kerckring's ossicle;
medullary c. centrum semiovale
microtubule-organizing c. a locus in interphase and mitotic cells from which most microtubules radiate; in the center of this c. is the centriole; this c. determines the polarity of cellular microtubules.
motor speech c. Broca's c
ossific c. c. of ossification
c. of ossification the site of earliest bone formation via accumulation of osteoblasts within connective tissue (membranous ossification) or of earliest destruction of cartilage prior to onset of ossification (endochondral ossification).punctum ossificationis [NA] , ossific c., point of ossification;
primary c. of ossification this is the first site where bone begins to form in the shaft of a long bone or in the body of an irregular bone.punctum ossificationis primarium [NA] , primary point of ossification;
reaction c. germinal c. of Flemming
respiratory c. the region in the medulla oblongata concerned with integrating afferent information to determine the signals to the respiratory muscles; the inspiratory and expiratory c.'s considered together.
c. of ridge the buccolingual midline of the residual ridge.
c. of rotation a point or line around which all other points in a body move. See axis.
satiety c. a term referring to the region of the ventromedial nucleus in the hypothalamus; destruction of this small region in the rat leads to continuous eating and extreme obesity.
secondary c. of ossification this is the center of bone formation appearing later than the punctum ossificationis primarium, usually in epiphysis.punctum ossificationis secundarium [NA] , secondary point of ossification;
semioval c. centrum semiovale
sensory speech c. Wernicke's c
speech c.'s areas of the cerebral cortex centrally involved in speech function; one is in the left inferior frontal gyrus, a second one in the supramarginal, angular, and first and second temporal gyri. See also Broca's c., Wernicke's c.
sphenotic c. one of the paired c.'s of ossification of the sphenoid bone.
vasomotor c. diffuse area of the reticular formation in the lateral medulla containing neurons that control vascular tone; consists of separate vasodepressor and vasopressor areas.
vital c. c. essential to life; usually refers to the centers located in the medulla oblongata which are necessary for the maintenance of respiration and circulation.
Wernicke's c. the region of the cerebral cortex thought to be essential for understanding and formulating coherent, propositional speech; it encompasses a large region of the parietal and temporal lobes near the lateral sulcus of the left cerebral hemisphere; corresponding approximately to Brodmann's areas 40, 39, and 22.sensory speech c., Wernicke's area, Wernicke's field, Wernicke's region, Wernicke's zone;


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