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| | The Autonomic Nervous System |
 | | The first set, called preganglionic neurons, originates in the brain stem or the spinal cord, and the second set, called ganglion cells or postganglionic neurons, lies outside the central nervous system in collections of nerve cells called autonomic ganglia. |
 | | The diagram to the left depicts this.) The axons of these neurons exit the spinal cord in the ventral roots and then synapse on either sympathetic ganglion cells or specialized cells in the adrenal gland called chromaffin cells. |
 | | This is characterized by the release of large quantities of epinephrine from the adrenal gland, an increase in heart rate, an increase in cardiac output, skeletal muscle vasodilation, cutaneous and gastrointestinal vasoconstriction, pupillary dilation, bronchial dilation, and piloerection. |
| www.becomehealthynow.com /article/bodynervousadvanced/822 (1644 words) |
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