Copyright © 2005 Pearson Education, Inc Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Objectives What is Autonomic Nervous System. Describe Sympathetic and Parasympathetic Nervous System. Give their Functions.

Copyright © 2005 Pearson Education, Inc Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

The Autonomic Nervous System and Visceral Sensory Neurons 1- Innervates smooth muscle, cardiac muscle, and glands 2- Regulates visceral functions: A) Heart rate, blood pressure, digestion, urination B) The general visceral motor division of the PNS Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

The Autonomic Nervous System and Visceral Sensory Neurons Figure 15.1 Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Comparison of Autonomic and Somatic Motor Systems One motor neuron extends from the CNS to skeletal muscle Axons are well myelinated, conduct impulses rapidly Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

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Comparison of Autonomic and Somatic Motor Systems Autonomic nervous system Chain of two motor neurons Preganglionic neuron Postganglionic neuron Conduction is slower due to thinly or unmyelinated axons Pre-ganglionic Post-ganglionic Ganglion Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Autonomic and Somatic Motor Systems Figure 15.2 Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Divisions of the Autonomic Nervous System Sympathetic and parasympathetic divisions Innervate mostly the same structures Cause opposite effects Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Divisions of the Autonomic Nervous System Sympathetic – “fight, flight, or fright” Activated during exercise, excitement, and emergencies Parasympathetic – “rest and digest” Concerned with conserving energy Copyright © 2005 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 Figure 15.3 Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

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 © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Neurotransmitters of Autonomic Nervous System Neurotransmitter released by preganglionic axons Acetylcholine for both branches (cholinergic) Neurotransmitter released by postganglionic axons Sympathetic – most release norepinephrine (adrenergic) Parasympathetic – release acetylcholine Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Anatomical Differences in Sympathetic and Parasympathetic Divisions Figure 15.4a Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Anatomical Differences in Sympathetic and Parasympathetic Divisions Figure 15.4b Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

The Parasympathetic Division Cranial outflow Comes from the brain Innervates organs of the head, neck, thorax, and abdomen Sacral outflow Supplies remaining abdominal and pelvic organs Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

The Parasympathetic Division Figure 15.5 Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Preganglionic fibers run via: Cranial Outflow Preganglionic fibers run via: Oculomotor nerve (III) Facial nerve (VII) Glossopharyngeal nerve (IX) Vagus nerve (X) Cell bodies located in cranial nerve nuclei in the brain stem Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Sacral outflow (S2-4): form pelvic splanchnic nerves Cranial outflow III - pupils constrict VII - tears, nasal mucus, saliva IX – parotid salivary gland X (Vagus n) – visceral organs of thorax & abdomen: Stimulates digestive glands Increases motility of smooth muscle of digestive tract Decreases heart rate Causes bronchial constriction Sacral outflow (S2-4): form pelvic splanchnic nerves Supply 2nd half of large intestine Supply all the pelvic (genitourinary) organs Copyright © 2005 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 blood pressure Preganglionic cell bodies Located in dorsal motor nucleus in the medulla Ganglionic neurons Confined within the walls of organs being innervated Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Parasympathetic Nervous System: Sacral Outflow Emerges from S2-S4 Innervates organs of the pelvis and lower abdomen Preganglionic cell bodies Located in visceral motor region of spinal gray matter Form splanchnic nerves Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Functions of Parasympathetic Nervous System Decreased Heart Rate Decreased Blood Pressure Pupil Constriction Increased Urination Decreased Sweating Bronchial Constriction Increased Salivation Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

The Sympathetic Division Basic organization Issues from T1-L2 Preganglionic fibers form the lateral gray horn Supplies visceral organs and structures of superficial body regions Contains more ganglia than the parasympathetic division Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Functions of Sympathetic Nervous System Increased Heart Rate Increased Blood Pressure Pupil Dilation Decreased Urination Increased Sweating Bronchial Dilation Decreased Salivation Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Sympathetic Trunk Ganglia Located on both sides of the vertebral column Linked by short nerves into sympathetic trunks Joined to ventral rami by white and gray rami communicantes Fusion of ganglia  fewer ganglia than spinal nerves Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Regardless of target, all begin same Preganglionic axons exit spinal cord through ventral root and enter spinal nerve Exit spinal nerve via communicating ramus Enter sympathetic trunk/chain where postganglionic neurons are Has three options… Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Options of preganglionic axons in sympathetic trunk Synapse on postganglionic neuron in chain ganglion then return to spinal nerve and follow its branch to the skin Ascend or descend within sympathetic trunk, synapse with a posganglionic neuron within a chain ganglion, and return to spinal nerve at that level and follow branches to skin Enter sympathetic chain, pass through without synapsing, form a splanchnic nerve that passes toward thoracic or abdominal organs These synapse in prevertebral ganglion in front of aorta Postganglionic axons follow arteries to organs Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

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Sympathetic Pathways to Periphery:Synapse in chain ganglia at same level or different level Figure 15.9 Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Pass through ganglia and synapse in prevertebral ganglion Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Sympathetic Trunk Ganglia Figure 15.8 Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

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Unpaired, not segmentally arranged Occur only in abdomen and pelvis Prevertebral Ganglia Unpaired, not segmentally arranged Occur only in abdomen and pelvis Lie anterior to the vertebral column Main ganglia Celiac, superior mesenteric, inferior mesenteric, inferior hypogastric ganglia Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Sympathetic Division of the ANS Figure 15.7 Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Sympathetic Pathways to the Head Figure 15.10 Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Sympathetic Pathways to Thoracic Organs Figure 15.11 Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Sympathetic Pathways to the Abdominal Organs Figure 15.12 Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Sympathetic Pathways to the Pelvic Organs Figure 15.13 Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

The Role of the Adrenal Medulla in the Sympathetic Division Major organ of the sympathetic nervous system Secretes great quantities epinephrine (a little norepinephrine) Stimulated to secrete by preganglionic sympathetic fibers Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

The Adrenal Medulla Figure 15.14 Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Visceral Sensory Neurons General visceral sensory neurons monitor: Stretch, temperature, chemical changes, and irritation Cell bodies are located in the dorsal root ganglia Visceral pain – perceived to be somatic in origin Referred pain Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

A Map of Referred Pain Figure 15.15 Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Visceral sensory and autonomic neurons Visceral Reflexes Visceral sensory and autonomic neurons Participate in visceral reflex arcs Defecation reflex Micturition reflex Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Visceral Reflex Arc Figure 15.16 Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

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 © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Disorders of the Autonomic Nervous System: Raynaud’s Disease Raynaud’s disease – characterized by constriction of blood vessels Provoked by exposure to cold or by emotional stress Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Disorders of the Autonomic Nervous System: Hypertension Hypertension – high blood pressure Can result from overactive sympathetic vasoconstriction Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Disorders of the Autonomic Nervous System: Mass Reflex Reaction Uncontrolled activation of autonomic and somatic motor neurons Affects quadriplegics and paraplegics Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

Disorders of the Autonomic Nervous System: Achalasia of the Cardia Defect in the autonomic innervation of the esophagus Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings