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11-13-2008, 10:43 AM
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In Remembrance
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http://www.answers.com/adrenal+medul...ookup&nafid=27
ADRENAL MEDULLA The adrenal medulla is part of the adrenal gland. It is located at the center of the gland, being surrounded by the adrenal cortex. Function Composed mainly of hormone-producing chromaffin cells, the adrenal medulla is the principal site of the conversion of the amino acid tyrosine into the catecholamines adrenaline (epinephrine), noradrenaline (norepinephrine), and dopamine. In response to stressors such as exercise or imminent danger, medullary cells release catecholamines into the blood in a 85:15 ratio of adrenaline to noradrenaline. [1] Notable effects of adrenaline and noradrenaline include increased heart rate and blood pressure, blood vessel constriction, bronchiole dilation, and increased metabolism, all of which are characteristic of the fight-or-flight response. Release of catecholamines is stimualted by nerve impulses, and receptors for catecholamines are widely distributed throughout the body. Origin Medullary cells are derived from the embryonic neural crest and, as such, are simply modified neurons. In particular, they are modified postganglionic cells of the sympathetic nervous system that have lost their axons and dendrites, receiving innervation from corresponding preganglionic fibers. Moreover, as the synapses between pre- and postganglionic fibers are called ganglia, the adrenal medulla is actually a ganglion of the sympathetic nervous system. ~~~~~~ substantia ni·gra (nī'grə, nĭg'rə) n. A layer of large pigmented nerve cells in the mesencephalon that produce dopamine and whose destruction is associated with Parkinson's disease. Also called nigra. http://www.answers.com/substantia%20nigra MESENCEPHALON / In biological anatomy, the mesencephalon (or midbrain) is the middle of three vesicles that arise from the neural tube that forms the brain of developing animals. Caudally the mesencephalon adjoins the pons (metencephalon) and rostrally it adjoins the diencephalon (Thalamus, hypothalamus, et al). http://www.answers.com/topic/mesencephalon
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with much love, lou_lou . . by . , on Flickr pd documentary - part 2 and 3 . . Resolve to be tender with the young, compassionate with the aged, sympathetic with the striving, and tolerant with the weak and the wrong. Sometime in your life you will have been all of these. |
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The Adrenal Medulla also produces Dopamine...
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