| autonomic fibres, preganglionic | Nerve fibres which project from the central nervous system to autonomic ganglia. In the sympathetic division most preganglionic fibres originate with neurons in the intermediolateral column of the spinal cord, exit via ventral roots from upper thoracic through lower lumbar segments, and project to the paravertebral ganglia; there they either terminate in synapses or continue through the splanchnic nerves to the prevertebral ganglia. In the parasympathetic division the fibres originate in neurons of the brainstem and sacral spinal cord. In both divisions the principal transmitter is acetylcholine but peptide cotransmitters may also be released. (12 Dec 1998) |
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| preganglionic | Situated proximal to or preceding a ganglion; referring specifically to the preganglionic motor neurons of the autonomic nervous system (located in the spinal cord and brainstem) and the preganglionic, myelinated nerve fibres by which they are connected to the autonomic ganglia. (05 Mar 2000) |
| preganglionic fibres | A fibre whose cell body is located in an autonomic nucleus in the spinal cord or brain stem and whose axon terminates in an autonomic (motor) ganglion; found in nerves conveying sympathetic or parasympathetic fibres. (05 Mar 2000) |
| preganglionic motor neuron | See: motor neuron. (05 Mar 2000) |
| autonomic | <physiology> Self controlling, functionally independent. (02 Jan 1998) |
| autonomic agents | Agents affecting the function of, or mimicking the actions of, the autonomic nervous system and thereby having an effect on such processes as respiration, circulation, digestion, body temperature regulation, certain endocrine gland secretions, etc. (12 Dec 1998) |
| autonomic denervation | The removal or interruption of some part of the autonomic nervous system for therapeutic or research purposes. (12 Dec 1998) |
| autonomic disorder | Disorganization of autonomic processes. (05 Mar 2000) |
| autonomic epilepsy | Episodes of autonomic dysfunction presumably due to diencephalic irritation. Synonym: diencephalic epilepsy, vasomotor epilepsy, vasovagal epilepsy. (05 Mar 2000) |
| autonomic fibres, postganglionic | Nerve fibres which project from cell bodies of autonomic ganglia to synapses on target organs. (12 Dec 1998) |
| autonomic ganglia | Visceral ganglia. See: autonomic nervous system. (05 Mar 2000) |
| autonomic hyperreflexia | <physiology> An autonomic response that may include hypertension, sweating, bradycardia and severe headache. Autonomic hyperreflexia may occur secondary to an injury to the upper spinal cord, during cystoscopy or with distention of the bladder or colon. (02 Jan 1998) |
| autonomic imbalance | A lack of balance between sympathetic and parasympathetic nervous systems, especially in relation to the vasomotor disturbances. Synonym: vasomotor imbalance. (05 Mar 2000) |
| autonomic motor neuron | See: motor neuron. (05 Mar 2000) |
| autonomic motor neurons | (preganglionic neuron's), by contrast, innervate smooth muscle fibres or glands only by the intermediary of a second, peripheral, neuron (postganglionic or ganglionic m. Neuron) located in an autonomic ganglion. See: motor endplate, autonomic nervous system. Synonym: anterior horn cell, motoneuron. (05 Mar 2000) |