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The Autonomic Nervous System and Visceral Sensory Neurons Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The ANS and Visceral Sensory Neurons The ANS – a system of motor neurons Innervates Smooth muscle Cardiac muscle Glands Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The ANS and Visceral Sensory Neurons The ANS – a system of motor neurons Regulates visceral functions Heart rate Blood pressure Digestion Urination The ANS is the General visceral motor division of the PNS Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Autonomic Nervous System and Visceral Sensory Neurons Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.1 Comparison of Autonomic and Somatic Motor Systems Somatic motor system One motor neuron extends from the CNS to skeletal muscle Axons are well myelinated, conduct impulses rapidly Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Comparison of Autonomic and Somatic Motor Systems Autonomic nervous system Chain of two motor neurons Preganglionic neuron Ganglionic neuron Conduction is slower than somatic nervous system due to Thinly myelinated or unmyelinated axons Motor neuron synapses in a ganglion Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Autonomic and Somatic Motor Systems Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.2 Divisions of the Autonomic Nervous System Sympathetic and parasympathetic divisions Chains of two motor neurons Innervate mostly the same structures Cause opposite effects Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Divisions of the Autonomic Nervous System Sympathetic – “fight, flight, or fright” Activated during EXTREME situations Exercise Excitement Emergencies Parasympathetic – “rest and digest” Concerned with conserving energy Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Anatomical Differences in Sympathetic and Parasympathetic Divisions Issue from different regions of the CNS Sympathetic – also called the thoracolumbar division Parasympathetic – also called the craniosacral division Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.3 Sympathetic part Lower center: located in lateral gray horn of spinal cord segments T1~L3 Sympathetic ganglia Paravertebral ganglia Prevertebral ganglia Paravertebral ganglia Arranged on either side of vertebral column Consist of 19~22 of ovalshaped ganglia Three cervical 10~12 thoracic 4 lumbar 2~3 sacral Ganglion impar: unpaired on the anterior face of coccyx Sympathetic trunk Formed by paravertebral ganglia and interganglionic branches Lie on either side of vertebral column from base of skull to coccyx The trunks of two side unite in front of the coccyx at a small swelling, the ganglion impar Prevertebral ganglia Lie anterior to vertebral column and near the arteries for which they are named Celiac ganglion Aorticorenal ganglion Superior mesenteric ganglion Inferior mesenteric ganglion Anatomical Differences in Sympathetic and Parasympathetic Divisions Length of postganglionic fibers Sympathetic – long postganglionic fibers Parasympathetic – short postganglionic fibers Branching of axons Sympathetic axons – highly branched Influences many organs Parasympathetic axons – few branches Localized effect Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Anatomical Differences in Sympathetic and Parasympathetic Divisions Neurotransmitter released by postganglionic axons Sympathetic – most release norepinephrine (adrenergic) Parasympathetic – release acetylcholine (cholinergic) Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Anatomical Differences in Sympathetic and Parasympathetic Divisions Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.4a Anatomical Differences in Sympathetic and Parasympathetic Divisions Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.4b Parasympathetic and Sympathetic Divisions Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Table 15.1 The Parasympathetic Division Cranial outflow Comes from the brain Innervates Organs of the head, neck, thorax, and abdomen Sacral outflow Innervation supplies Remaining abdominal and pelvic organs Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Cranial portion Ⅲ ciliary ganglion sphincter pupillae and ciliary muscles lacrimal gland Ⅶ pterygopalatine ganglion Ⅸ Ⅹ sublingual gland submandibular gland submandibular ganglion parotid gland otic ganglion heart, lungs, liver, spleen kidneys,alimentary tract terminal ganglia as far as left colic flexure PowerPoint® Lecture Slides prepared by Leslie Hendon, University of Alabama, Birmingham 15 HUMAN ANATOMY fifth edition MARIEB | MALLATT | WILHELM Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Outflow via the Vagus Nerve (X) Fibers innervate visceral organs of the thorax and most of the abdomen Stimulates Digestion, reduction in heart rate and reduction in blood pressure Preganglionic cell bodies Located in dorsal motor nucleus in the medulla Ganglionic neurons Confined within the walls of organs being innervated Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Path of the Vagus Nerve Sends branches through Autonomic nerve plexuses Cardiac plexus Pulmonary plexus Esophageal plexus Celiac plexus Superior mesenteric plexus Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Path of the Vagus Nerve Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.6 Sacral portion Preganglionic fibers from sacral parasympathetic nucleus leave spinal cord with anterior roots of the spinal nerves S2~S4, Then leave sacral nerves and form pelvic splanchnic nerve and travel by way of pelvic plexus to terminal ganglia in pelvic cavity Postganglionic fibers terminate in descending and sigmoid colon, rectum and pelvic viscera Main differences between sympathetic and parasympathetic Visceral plexuses Cardiac plexuses Superficial , below aortic arch Deep, anterior to bifurcation on trachea Pulmonary plexus Celiac plexus Abdominal aortic plexus Hypogastric plexus Superior hypogastric plexus Inferior hypogastric plexus (pelvic plexus) Autonomic plexuses in the abdomen and pelvis Illustrator: Markus Voll Gilroy et al., THIEME Atlas of Anatomy. All rights reserved. © THIEME 2008, www.thieme.com Sympathetic Trunk Ganglia Joined to ventral rami by white and gray rami communicantes Fusion of ganglia fewer ganglia than spinal nerves Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Trunk Ganglia Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.8 Autonomic nervous system circuitry. Illustrator: Karl Wesker Gilroy et al., THIEME Atlas of Anatomy. All rights reserved. © THIEME 2008, www.thieme.com Three fates of preganglionic fibers 15 pairs white communicating branch Preganglionic fibers (only spinal levels T1~L3 have white communicating branch) Sympathetic trunk Three fates of preganglionic fibers Relay in corresponding ganglion Ascend or descend in sympathetic trunk and relay in higher or lower ganglia Pass without synapse to a prevertebral ganglion for relay Three fates of postganglionic fibers Back to a spinal nerve along gray communicating branches ( 31 pairs ) to terminate in blood vessels, arrectores pilorum and sweat glands of head, neck, trunk and limbs The fibers from their networks around blood vessels passing to visceral end organs Terminate directly in certain organs Sympathetic Pathways to the Body Periphery Innervate Sweat glands Arrector pili muscles Peripheral blood vessels Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways to the Head Preganglionic fibers originate in spinal cord at T1–T4 Fibers ascend in the sympathetic trunk Synapse in superior cervical ganglion Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways to the Head Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.10 Sympathetic Pathways to Thoracic Organs Preganglionic fibers originate at spinal levels T1– T6 Some fibers synapse in nearest sympathetic trunk ganglion Postganglionic fibers run directly to the organ supplied Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways to Thoracic Organs Sympathetic fibers to heart have a less direct route Functions Increase heart rate Dilate bronchioles Dilate blood vessels to the heart wall Inhibit muscles and glands in the esophagus and digestive system Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways to Thoracic Organs Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.11 Sympathetic Pathways to Abdominal Organs Preganglionic fibers originate in spinal cord (T5– L2) Pass through adjacent sympathetic trunk ganglia Then travel in thoracic splanchnic nerves Synapse in prevertebral ganglia on the abdominal aorta Celiac and superior mesenteric ganglia Inhibit activity of muscles and glands in visceral organs Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways to the Abdominal Organs Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.12 Greater splanchnic nerve formed by preganglionic fibers from T5~T9 ganglia, and relay in celiac ganglion. Lesser splanchnic nerve formed by preganglionic fibers from T10~T12 ganglia, and relay in aorticorenal ganglion. The postganglionic fibers supply the liver, spleen, kidney and alimentary tract as far as the left colic flexure. Sympathetic Pathways to the Pelvic Organs Preganglionic fibers originate in spinal cord (T10 –L2) Some fibers synapse in sympathetic trunk Other preganglionic fibers synapse in prevertebral ganglia Postganglionic fibers proceed from plexuses to pelvic organs Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways to the Pelvic Organs Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.13 The Adrenal Medulla Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.14 Visceral Sensory Neurons General visceral sensory neurons monitor Stretch, temperature, chemical changes, and irritation Cell bodies are located in the dorsal root ganglion Visceral pain – perceived to be somatic in origin referred pain Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings A Map of Referred Pain Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.15 Visceral Reflexes Visceral sensory and autonomic neurons Participate in visceral reflex arcs Defecation reflex Micturition reflex Some are simple spinal reflexes Others do not involve the CNS Strictly peripheral reflexes Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Visceral Reflex Arc Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.16 Central Control of the ANS Control by the brain stem and spinal cord Reticular formation exerts most direct influence Medulla oblongata Periaqueductal gray matter Control by the hypothalamus and amygdala Hypothalamus – the main integration center of the ANS Amygdala – main limbic region for emotions Control by the cerebral cortex Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Central Control of the ANS Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.17 Disorders of the Autonomic Nervous System Raynaud’s disease – characterized by constriction of blood vessels Provoked by exposure to cold or by emotional stress Hypertension – high blood pressure Can result from overactive sympathetic vasoconstriction Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathectomy: raynaud disease PAMEL P for Ptosis, Anhydrosis, Miosis, Enophthalmos and Loss of ciliospinal reflex Disorders of the Autonomic Nervous System Achalasia of the cardia Defect in the autonomic innervation of the esophagus Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 1 Esophagrams of a patient with early achalasia pre- and posttreatment. GI Motility online (May 2006) | doi:10.1038/gimo53 The ANS Throughout Life Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.18 The ANS Throughout Life Efficiency of the ANS declines with advancing age Constipation due to reduced mobility of gastrointestinal (GI) tract Dry eyes due to reduced tear formation Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings EPSP :Excitatory post synaptic potential Regulatory effects of the autonomic neurotransmitters Two Symp. Receptor α & β α is excitatory β is often inhibitory Illustrator: Karl Wesker Gilroy et al., THIEME Atlas of Anatomy. All rights reserved. © THIEME 2008, www.thieme.com Stimulating & Blocking agents Stimulating agents such as nicotine, lobeline,methylphenol piperazium Blocking agents such as nicotin in high concentration and hexamethonium, tetraethylammonium Blocking of cholinergic & adernergic receptors Cholinergic atropine(antagonist) Adrenergic Alpha receptor phenoxybenzamine Beta receptor proprranolol