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5/20/09 1 Autonomic Nervous System Anthony Nicholson, B.Sc. M.Chiro. D.A.C.N.B Spine Partners Wahroonga Wahroonga Specialist Centre 13/176 Fox Valley Road Wahroonga NSW 2076 1 Basic Function of the ANS • That part of the nervous system that maintains homeostasis and promotes survivability by delivering blood, food and oxygen • There is an embryological relationship between the ANS and the neural tissues that sense external environment – lateral crest cells • Any activation of sensory ganglia will activate autonomic neurons for a corresponding response in fuel delivery 2 ANS • ANS is basically a visceral sensory and motor system • Also referred to as the involuntary motor system in contrast to voluntary (somatic) motor system • Whereas somatic motor system innervates skeletal muscle the ANS innervates: – Cardiac Muscle – Smooth Muscle – Glands 3 Central Circuitry of ANS • Central Autonomic Network (CAN) • Insula – primary viscerosensory cortex • Ventromedial and prefrontal cortices and anterior cingulate initiate ANS responses associated with affective behaviour • Amygdala receives exteroreceptive and interoreceptive information and tags it with emotional signi±cance • Hypothalamus – integrates autonomic and endocrine responses critical for homeostasis 4
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5/20/09 2 ANS Outfow • Sympathetic • Parasympathetic • Cell Bodies – Primary (Preganglionic) • located in brainstem nuclei and Intermediolateral column oF spinal cord – Secondary ( Postganglionic) • Located in the autonomic ganglia 5 Both SNS and PNS have two neurons in series in the motor outfow. In the parasympathetic system the ganglion is a small structure embedded in the target organ, not a separate structure like the sympathetic ganglia. BOTH neurons in the parasympathetic outfow are cholinergic. The second neuron acts on MUSCARINIC cholinergic receptors (not nicotinic). 6 SNS Preganglionic Neurons Located in IML column oF spinal cord T1-L2/3 Mostly myelinated B ±bres Accompany ventral roots Axons Form white communicating rami that may: 1. Synapse in paravertebral ganglia at same level 2. May pass up or down sympathetic to synapse at another level 3. Pass directly to the prevertebral ganglia 4. Synapse directly on the adrenal medulla 7 SNS Postganglionic Neurons • Mostly unmyelinated C ±bres • Axons Form gray communicating rami and then course with all spinal nerves • PerForm Following basic Functions in peripheral
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This note was uploaded on 07/15/2011 for the course ECO 2023 taught by Professor Mr.raza during the Summer '10 term at FAU.

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