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Chapter 16 The Autonomic Nervous System and Higher-Order Functions Lecture Presentation by Lee Ann Frederick University of Texas at Arlington © 2015 Pearson Education, Inc. An Introduction to the ANS and HigherOrder Functions • Learning Outcomes • 16-1 Compare the organization of the autonomic nervous system with that of the somatic nervous system. • 16-2 Describe the structures and functions of the sympathetic and parasympathetic division of the autonomic nervous system. • 16-3 Describe the mechanisms of sympathetic and parasympathetic neurotransmitter release and their effects on target organs and tissues. © 2015 Pearson Education, Inc. An Introduction to the ANS and HigherOrder Functions • Learning Outcomes. • 16-4 Describe the hierarchy of interacting levels of control in the autonomic nervous system, including the significance of visceral reflexes. • 16-5 Summarize the effects of aging on the nervous system and give examples of interactions between the nervous system and other organ systems. © 2015 Pearson Education, Inc. An Introduction to the ANS and HigherOrder Functions • Somatic Nervous System (SNS) • Operates under conscious control • Seldom affects long-term survival • SNS controls skeletal muscles • Autonomic Nervous System (ANS) • Operates without conscious instruction • ANS controls visceral effectors • Coordinates vitals system functions • Cardiovascular, respiratory, digestive, urinary, reproductive • 5 year survival after heart attack: increased since 1960 © 2015 Pearson Education, Inc. 16-1 Autonomic Nervous System • Organization of the ANS • Integrative centers ViscMotN (PreGN) G PostGN Efec • Integrative centers • For autonomic activity in hypothalamus • Neurons here are comparable to upper motor neurons in SNS • Synapses with ganglionic neurons © 2015 Pearson Education, Inc. 16-1 Autonomic Nervous System • Organization of the ANS • Visceral motor neurons • In brain stem and spinal cord, are known as preganglionic neurons • Preganglionic fibers • Axons of preganglionic neurons • Leave CNS and synapse on ganglionic neurons © 2015 Pearson Education, Inc. 16-1 Autonomic Nervous System • Visceral Motor Neurons • Autonomic ganglia • Contain many ganglionic neurons • Ganglionic neurons innervate visceral effectors • Such as cardiac muscle, smooth muscle, glands, and adipose tissue • Postganglionic fibers • Axons of ganglionic neurons © 2015 Pearson Education, Inc. Figure 16-1a The Organization of the Somatic and Autonomic Nervous Systems. Upper motor neurons in primary motor cortex Brain Somatic motor nuclei of brain stem Skeletal muscle Motor neurons of the CNS exerts direct control over skeletal muscles Lower motor neurons Spinal cord Somatic motor nuclei of spinal cord Skeletal muscle a Somatic nervous system © 2015 Pearson Education, Inc. Figure 16-1b The Organization of the Somatic and Autonomic Nervous Systems. Visceral motor nuclei in hypothalamus Brain Preganglionic neuron Visceral Effectors Smooth muscle Autonomic ganglia Glands Cardiac muscle Ganglionic neurons Autonomic nuclei in brain stem Spinal cord Adipocytes Motor neurons of the CNS synapse on visceral motor neurons in autonomic ganglia, and these ganglionic neurons control visceral effectors © 2015 Pearson Education, Inc. Autonomic nuclei in spinal cord Preganglionic neuron b Autonomic nervous system 16-1 Divisions of the ANS • The Autonomic Nervous System • Operates largely outside our awareness • Control activities of target organs • Modify or alter some ongoing activity • Two divisions 1. Sympathetic division • Increases alertness, metabolic rate, and muscular abilities • Kicks in only during exertion, stress, or emergency (F or F) 2. Parasympathetic division • Reduces metabolic rate and promotes digestion • Controls during resting conditions (R and D) © 2015 Pearson Education, Inc. 16-1 Divisions of the ANS • Sympathetic and Parasympathetic Division 1. Most often, these two divisions have opposing effects (antagonist) • If the sympathetic division causes excitation, the parasympathetic causes inhibition 2. The two divisions may also work independently • Only one division innervates some structures 3. The two divisions may work together, with each controlling one stage of a complex process © 2015 Pearson Education, Inc. 16-1 Divisions of the ANS • Sympathetic Division –Preganglionic fibers originates in thoracic and superior lumbar; (thoracolumbar, between T1 – L2 segments) • • • • Synapse in ganglia near spinal cord Preganglionic fibers are short Postganglionic fibers are long Prepares body for crisis, producing a “fight or flight” response • Stimulates tissue metabolism • Increases alertness © 2015 Pearson Education, Inc. 16-1 Divisions of the ANS • Seven Responses to Increased Sympathetic Activity 1. 2. 3. 4. 5. Heightened mental alertness Increased metabolic rate Reduced digestive and urinary functions Energy reserves activated Increased respiratory rate and respiratory passageways dilate 6. Increased heart rate and blood pressure 7. Sweat glands activated © 2015 Pearson Education, Inc. 16-1 Divisions of the ANS • Parasympathetic Division • Preganglionic fibers originate in brain stem and sacral segments of spinal cord; craniosacral • Synapse in ganglia close to (or within) target organs • Preganglionic fibers are long • Postganglionic fibers are short • Parasympathetic division stimulates visceral activity • Conserves energy and promotes sedentary activities © 2015 Pearson Education, Inc. 16-1 Divisions of the ANS • Five Responses to Increased Parasympathetic Activity 1. Decreased metabolic rate 2. Decreased heart rate and blood pressure 3. Increased secretion by salivary and digestive glands 4. Increased motility and blood flow in digestive tract 5. Urination and defecation stimulation © 2015 Pearson Education, Inc. Figure 16-2 Overview of the Autonomic Nervous System (Part 1 of 2). Sympathetic Division (Thoracolumbar) Preganglionic Neurons Preganglionic neurons are located in the lateral gray horns of spinal segments T1–L2. Ganglia Ganglia are located near the spinal cord. Preganglionic fibers release acetylcholine (Ach), stimulating ganglionic neurons. Target Organs Most postganglionic fibers release norepinephrine (NE) at neuroeffector junctions. Sympathetic activation “Fight or flight” response KEY Preganglionic fibers Postganglionic fibers © 2015 Pearson Education, Inc. Figure 16-2 Overview of the Autonomic Nervous System (Part 2 of 2). Parasympathetic Division (Craniosacral) Preganglionic Neurons Preganglionic neurons in brain stem and in lateral portion of anterior gray horns of S2–S4. Ganglia Ganglia are in or near the target organ. Preganglionic fibers release acetylcholine (Ach), stimulating ganglionic neurons. Target Organs All postganglionic fibers release Ach at neuroeffector junctions. Parasympathetic stimulation “Rest and digest” response KEY Preganglionic fibers Postganglionic fibers © 2015 Pearson Education, Inc. 16-1 Divisions of the ANS • Enteric Nervous System (ENS) • Third division of ANS • Extensive network in digestive tract walls • Complex visceral reflexes coordinated locally plus influence of sympathetic and parasympathethic divisions • Neurotransmitters are the same found in the brain © 2015 Pearson Education, Inc. 16-2 The Sympathetic Division • Ganglionic Neurons • Occur in three locations 1. Sympathetic chain ganglia • On both sides of vertebral column (paravertebral) • Control effectors: • In body wall • Inside thoracic cavity • In head, and limbs 2. Collateral ganglia • Are anterior to vertebral bodies (prevertebral) • Innervate tissues and organs in abdominopelvic cavity © 2015 Pearson Education, Inc. Figure 16-3a Sites of Ganglia in Sympathetic Pathways. a SYMPATHETIC CHAIN GANGLIA Spinal nerve Preganglionic neuron Autonomic ganglion of right sympathetic chain Autonomic ganglion of left sympathetic chain Innervates visceral effectors by spinal nerves White ramus Sympathetic nerve (postganglionic fibers) Ganglionic neuron Gray ramus Innervates visceral organs in thoracic cavity by sympathetic nerves Note: Both innervation patterns occur on each side of the body. © 2015 Pearson Education, Inc. KEY Preganglionic neurons Ganglionic neurons Figure 16-3b Sites of Ganglia in Sympathetic Pathways. COLLATERAL GANGLIA b Lateral gray horn White ramus Splanchnic nerve (preganglionic fibers) Postganglionic fibers © 2015 Pearson Education, Inc. Collateral ganglion Innervates visceral organs in abdominopelvic cavity 16-2 The Sympathetic Division • 3. Adrenal Medullae (Suprarenal Medullae) • • • • Modified sympathetic ganglia Center suprarenal medulla Very short axons When stimulated, release neurotransmitters into bloodstream (not at synapse) • Neurotransmitters then function as hormones to affect target cells throughout body © 2015 Pearson Education, Inc. Figure 16-3c Sites of Ganglia in Sympathetic Pathways. c Preganglionic fibers Endocrine cells (specialized ganglionic neurons) © 2015 Pearson Education, Inc. THE ADRENAL MEDULLAE Adrenal medullae Secretes neurotransmitters into general circulation 16-2 The Sympathetic Division • Fibers in Sympathetic Division • Preganglionic fibers • Are relatively short • Ganglia located near spinal cord • Postganglionic fibers • Are relatively long • Except at adrenal medullae © 2015 Pearson Education, Inc. 16-2 The Sympathetic Division • Organization and Anatomy of the Sympathetic Division • Ventral roots of spinal segments T1–L2 contain sympathetic preganglionic fibers • Carry myelinated preganglionic fibers into sympathetic chain ganglion • May synapse at collateral ganglia or in adrenal medullae © 2015 Pearson Education, Inc. 16-2 The Sympathetic Division • Sympathetic Chain Ganglia • Preganglionic fibers • One preganglionic fiber synapses on many ganglionic neurons • Fibers interconnect sympathetic chain ganglia • Each ganglion innervates particular body segment(s) • Preganglionic neurons • Limited to spinal cord segments T1–L2 • White rami (myelinated preganglionic fibers) • Innervate neurons in: • Cervical, inferior lumbar, and sacral sympathetic chain ganglia © 2015 Pearson Education, Inc. 16-2 The Sympathetic Division • Sympathetic Chain Ganglia • Postganglionic fibers control visceral effectors • In body wall, head, neck, or limbs • Postganglionic fibers innervate effectors • Sweat glands of skin • Smooth muscles in superficial blood vessels • Postganglionic fibers innervating structures in thoracic cavity form bundles • Sympathetic nerves © 2015 Pearson Education, Inc. 16-2 The Sympathetic Division • Sympathetic Chain Ganglia • Postganglionic sympathetic fibers • In head and neck leave superior cervical sympathetic ganglia • Supply the regions and structures innervated by cranial nerves III, VII, IX, X © 2015 Pearson Education, Inc. Figure 16-4 The Distribution of Sympathetic Innervation (Part 2 of 4). Eye Pons Salivary glands Sympathetic nerves Heart Cardiac and pulmonary plexuses T1 T2 T3 T4 KEY Preganglionic fibers Postganglionic fibers © 2015 Pearson Education, Inc. Lung Figure 16-4 The Distribution of Sympathetic Innervation (Part 3 of 4). T1 T2 T3 T4 T5 T6 T7 KEY Greater splanchnic nerve Preganglionic fibers Postganglionic fibers Celiac ganglion Superior mesenteric ganglion Liver and gallbladder T8 T9 T10 T11 T12 L1 L2 L3 L4 L5 S1 S2 S3 S4 Stomach Lesser splanchnic nerve Spleen Pancreas Large intestine Lumbar splanchnic nerves Small intestine Inferior mesenteric ganglion Adrenal medulla Sacral splanchnic nerves Kidney S5 Coccygeal ganglia (Co1) fused together (ganglion impar) © 2015 Pearson Education, Inc. Uterus Ovary Penis Scrotum Urinary bladder 16-2 The Sympathetic Division • Collateral Ganglia • Receive sympathetic innervation via sympathetic preganglionic fibers • Splanchnic nerves • Formed by preganglionic fibers that innervate collateral ganglia • In dorsal wall of abdominal cavity © 2015 Pearson Education, Inc. 16-2 The Sympathetic Division • Collateral Ganglia • Postganglionic fibers • Innervate variety of visceral tissues and organs • Reduction of blood flow and energy by organs not vital to short-term survival • Release of stored energy reserves © 2015 Pearson Education, Inc. 16-2 The Sympathetic Division • Collateral Ganglia • Preganglionic fibers from inferior thoracic segments • End at celiac ganglion or superior mesenteric ganglion • Preganglionic fibers from lumbar segments • Form splanchnic nerves • End at inferior mesenteric ganglion © 2015 Pearson Education, Inc. 16-2 The Sympathetic Division • Collateral Ganglia • Celiac ganglion • Postganglionic fibers innervate stomach, liver, gallbladder, pancreas, and spleen • Superior mesenteric ganglion • Postganglionic fibers innervate small intestine and proximal 2/3 of large intestine • Inferior mesenteric ganglion • Postganglionic fibers provide sympathetic innervation to portions of: • • • • © 2015 Pearson Education, Inc. Large intestine Kidney Urinary bladder Sex organs 16-2 The Sympathetic Division • Adrenal Medullae • Preganglionic fibers entering adrenal gland proceed to center (adrenal medulla) • Modified sympathetic ganglion • Preganglionic fibers synapse on neuroendocrine cells • Specialized neurons secrete hormones into bloodstream © 2015 Pearson Education, Inc. 16-2 The Sympathetic Division • Adrenal Medullae • Neuroendocrine cells • Secrete neurotransmitters epinephrine (E) and norepinephrine (NE) • Epinephrine • Also called adrenaline • Is 75–80 percent of secretory output • Remaining is norepinephrine (NE) • Noradrenaline © 2015 Pearson Education, Inc. 16-2 The Sympathetic Division • Adrenal Medullae • Bloodstream carries neurotransmitters through body • Causing changes in metabolic activities of different cells • Including cells NOT innervated by sympathetic postganglionic fibers • Effects last longer • Hormones continue to diffuse out of bloodstream © 2015 Pearson Education, Inc. 16-2 The Sympathetic Division • Sympathetic Activation • Change activities of tissues and organs by: • Releasing NT at peripheral synapses • Distributing E and NE throughout body in bloodstream • Target specific effectors, smooth muscle fibers in blood vessels of skin • Are activated in reflexes • Do not involve other visceral effectors © 2015 Pearson Education, Inc. 16-2 The Sympathetic Division • Changes Caused by Sympathetic Activation • • • • • Increased alertness Feelings of energy and euphoria Change in breathing Elevation in muscle tone Mobilization of energy reserves © 2015 Pearson Education, Inc. 16-3 Various Sympathetic Neurotransmitters • Stimulation of Sympathetic Preganglionic Neurons • Releases ACh at synapses with ganglionic neurons • Excitatory effect on ganglionic neurons • Ganglionic Neurons • Release neurotransmitters (NE, ACh) at specific target organs © 2015 Pearson Education, Inc. 16-3 Various Sympathetic Neurotransmitters • Ganglionic Neurons • Axon terminals • Release NE at most varicosities • Called adrenergic neuron • Monoamine oxidase (MAO) • Catechol O methyltransferase (COMT) • Some ganglionic neurons release ACh instead • Are located in body wall, skin, brain, and skeletal muscles • Called cholinergic neurons • AChe © 2015 Pearson Education, Inc. Figure 16-5 Sympathetic Varicosities. Preganglionic fiber (myelinated) Ganglionic neuron Ganglion Postganglionic fiber (unmyelinated) Varicosities Vesicles containing norepinephrine (NE) Mitochondrion Schwann cell cytoplasm 5 μm Smooth muscle cells © 2015 Pearson Education, Inc. Varicosities 16-3 Various Sympathetic Neurotransmitters • Sympathetic Stimulation and the Release of NE and E • Effects occurs primarily from interactions of NE and E with: 1. Alpha receptors - NE more potent - E same potency 2. Beta receptors - NE less potent - E same potency • Two types of adrenergic membrane receptors • Activates enzymes on inside of cell membrane via G proteins (2nd messengers) © 2015 Pearson Education, Inc. 16-3 Various Sympathetic Neurotransmitters • Alpha receptors • Alpha-1 (1) • More common type of alpha receptor • Releases intracellular calcium ions from reserves in endoplasmic reticulum • Has excitatory effect on target cell • In smooth muscles • Vessels constriction • Closing sphincters © 2015 Pearson Education, Inc. 16-3 Various Sympathetic Neurotransmitters • Alpha receptors • Alpha-2 (2) • Lowers cAMP levels in cytoplasm • Has inhibitory effect on the cell • Helps coordinate sympathetic and parasympathetic activities • When sympathetic division is active: • NE is released • Binds to 2, on parasympathetic efectors (neuromuscular and neuroglandular) and inhibits their activity © 2015 Pearson Education, Inc. 16-3 Various Sympathetic Neurotransmitters • Beta () receptors • Affect membranes in many organs (skeletal muscles, lungs, heart, and liver) • Trigger metabolic changes in target cell via G proteins • Stimulation increases intracellular cAMP levels • Three Main Types of Beta Receptors 1. Beta-1 (1) 2. Beta-2 (2) 3. Beta-3 (3) © 2015 Pearson Education, Inc. 16-3 Various Sympathetic Neurotransmitters • Three Main Types of Beta Receptors 1. Beta-1 (1) • Increases metabolic activity, skeletal muscle • Heart, increase heart rate and force of contraction 2. Beta-2 (2) (inhibition) • Triggers relaxation of smooth muscles along respiratory tract • Easier breathing, respiratory therapy 3. Beta-3 (3) • Leads to lipolysis, the breakdown of triglycerides in adipocytes • Make fatty acids available for other tissues © 2015 Pearson Education, Inc. 16-3 Various Sympathetic Neurotransmitters • Sympathetic Stimulation and the Release of Ach • Cholinergic (ACh) sympathetic terminals • Innervate sweat glands of skin and blood vessels of skeletal muscles and brain • Stimulate sweat gland secretion and dilate blood vessels © 2015 Pearson Education, Inc. 16-3 Various Sympathetic Neurotransmitters • Sympathetic Stimulation and the Release of NO • Nitroxidergic synapses • Release nitric oxide (NO) as neurotransmitter • Neurons innervate smooth muscles in walls of blood vessels in skeletal muscles and the brain • Produce vasodilation and increased blood flow © 2015 Pearson Education, Inc. Summary: Sympathetic Division • Includes: • 2 sets of chain ganglia • 3 collateral ganglia • two adrenal ganglia • Preganglionic fibers shorts, post ganglionic are long • ganglia are near spinal cord • Adrenal: very short fibers direct to bloodstream • Extensive divergence: • a single sympathetic motor neuron can control a variety of visceral effectors producing a complex and coordinated response. © 2015 Pearson Education, Inc. Summary: Sympathetic Division •All preG neurons release ACh at synapses with ganglionic neurons •Most postG neurons release NE • a few release Ach or NO •The effector response depends on the 2nd messenger triggered by activation of G proteins by NE o E to α or β receptors. © 2015 Pearson Education, Inc. 16-4 The Parasympathetic Division • Autonomic Nuclei • Preganglionics neurons • Are contained in the mesencephalon, pons, and medulla oblongata • Associated with cranial nerves III, VII, IX, X • In lateral gray horns of spinal segments S2–S4 © 2015 Pearson Education, Inc. 16-4 The Parasympathetic Division • Ganglionic Neurons in Peripheral Ganglia • Terminal ganglion • Near target organ • Usually paired • Intramural ganglion • Embedded in or within tissues of target organ © 2015 Pearson Education, Inc. 16-4 The Parasympathetic Division • Organization and Anatomy of the Parasympathetic Division • Parasympathetic preganglionic fibers leave brain as components of cranial nerves • • • • III (oculomotor) VII (facial) IX (glossopharyngeal) X (vagus) • Parasympathetic preganglionic fibers leave spinal cord at sacral level • S2-S4 © 2015 Pearson Education, Inc. 16-4 The Parasympathetic Division • Oculomotor(III), Facial(VII), and Glossopharyngeal Nerves(IX) • Control visceral structures in head • Synapse in ganglia; • • • • ciliary pterygopalatine, submandibular otic ganglia • Short postganglionic fibers continue to their peripheral targets © 2015 Pearson Education, Inc. 16-4 The Parasympathetic Division • Vagus Nerve(X) • Provides preganglionic parasympathetic innervation to structures in: • Neck • Thoracic and abdominopelvic cavities • as distant as a distal portion of large intestine • Provides 75 percent of all parasympathetic outflow © 2015 Pearson Education, Inc. Figure 16-6 The Distribution of Parasympathetic Innervation (Part 1 of 2). Pterygopalatine ganglion N III Lacrimal gland Eye Ciliary ganglion Pons N VII N IX Submandibular ganglion Salivary glands Otic ganglion N X (Vagus) Heart Lungs Oculomotor(III) Facial(VII) Glossopharyngeal Nerves(IX) Vagus (X) © 2015 Pearson Education, Inc. 16-4 The Parasympathetic Division • Sacral Segments of Spinal Cord • Preganglionic fibers carry sacral parasympathetic output • Do not join ventral roots of spinal nerves, instead form pelvic nerves • • • • • Pelvic nerves innervate intramural ganglia in walls of: kidneys urinary bladder portions of large intestine sex organs © 2015 Pearson Education, Inc. Figure 16-6 The Distribution of Parasympathetic Innervation (Part 2 of 2). Lungs Autonomic plexuses (see Figure 16-8) Liver and gallbladder Stomach Spleen Pancreas Large intestine Pelvic nerves Small intestine Rectum Spinal cord Kidney S2 S3 S4 KEY Preganglionic fibers Postganglionic fibers © 2015 Pearson Education, Inc. Uterus Ovary Penis Scrotum Urinary bladder 16-4 The Parasympathetic Division • Parasympathetic Activation • • • • • • centers on relaxation food processing energy absorption localized effects last a few seconds at most Anabolic system • Raisin up nutrient content in the blood © 2015 Pearson Education, Inc. 16-4 The Parasympathetic Division • Major Effects of Parasympathetic Division • Constriction of the pupils • To restrict the amount of light that enters the eyes • Focusing of the lenses of the eyes on nearby objects • Secretion by digestive glands • Salivary, gastric glands, intestinal glands • the pancreas (exocrine and endocrine) • the liver © 2015 Pearson Education, Inc. 16-4 The Parasympathetic Division • Major Effects of Parasympathetic Division • Secretion of hormones • Promote the absorption and utilization of nutrients by peripheral cells • Changes in blood flow and glandular activity • Associated with sexual arousal • Increase in smooth muscle activity • Along the digestive tract, peristalsis © 2015 Pearson Education, Inc. 16-4 The Parasympathetic Division • Major Effects of Parasympathetic Division • Stimulation and coordination of defecation • Contraction of the urinary bladder during urination • Constriction of the respiratory passageways • Reduction in heart rate and in the force of contraction © 2015 Pearson Education, Inc. 16-5 Parasympathetic Neurons Release ACh • Neuromuscular and Neuroglandular Junctions • All PS fibers release ACh as neurotransmitter • Effects of stimulation are short lived • Inactivated by acetylcholinesterase (AChE) at synapse • ACh is also inactivated by tissue cholinesterase in surrounding tissues © 2015 Pearson Education, Inc. 16-5 Parasympathetic Neurons Release ACh • Two Types of Membrane Receptors and Responses • Nicotinic receptors • On surfaces of ganglion cells (sympathetic and parasympathetic) • On neuromuscular junction of Somatic Nervous System • Exposure to ACh causes excitation of ganglionic neuron or muscle fiber • Open Na+ channels in post sinaptic membrane © 2015 Pearson Education, Inc. 16-5 Parasympathetic Neurons Release ACh • Muscarinic receptors • At cholinergic neuromuscular or neuroglandular junctions (parasympathetic) • At few cholinergic junctions (sympathetic) • G proteins • Effects are longer lasting than nicotinic receptors • Can be excitatory or inhibitory • Response reflects activation or inactivation of specific enzymes © 2015 Pearson Education, Inc. 16-5 Parasympathetic Neurons Release ACh • Dangerous Environmental Toxins • Produce exaggerated, uncontrolled responses • Nicotine • 3mg/g on tobacco • Binds to nicotinic receptors • Targets autonomic ganglia and skeletal neuromuscular junctions • Poisoning with 50 mg ingested or absorbed through skin • Signs and symptoms: • Vomiting, diarrhea, high blood pressure, rapid heart rate, sweating, profuse salivation, convulsions • May result in coma or death © 2015 Pearson Education, Inc. 16-5 Parasympathetic Neurons Release ACh • Dangerous Environmental Toxins • Produce exaggerated, uncontrolled responses • Muscarine • Binds to muscarinic receptors • Targets parasympathetic neuromuscular or neuroglandular junctions • Signs and symptoms: • Salivation, nausea, vomiting, diarrhea, constriction of respiratory passages, low blood pressure, slow heart rate (bradycardia) • Sweating • Amanita muscaria © 2015 Pearson Education, Inc. Amanita muscaria © 2015 Pearson Education, Inc. Table 16-1 Adrenergic and Cholinergic Receptors of the ANS. © 2015 Pearson Education, Inc. 16-6 Dual Innervation: S y PS interaction • Sympathetic Division • Widespread impact • Reaches organs and tissues throughout body • Parasympathetic Division • Innervates only specific visceral structures • Sympathetic and Parasympathetic Division • Most vital organs receive instructions from both sympathetic and parasympathetic divisions • Dual innervation • Two divisions commonly have opposing effects © 2015 Pearson Education, Inc. Figure 16-7 Summary: The Anatomical Differences between the Sympathetic and Parasympathetic Divisions. Sympathetic Parasympathetic CNS Preganglionic neuron PNS Preganglionic fiber Sympathetic ganglion KEY Neurotransmitters Acetylcholine Norepinephrine or Epinephrine Ganglionic neurons Bloodstream Postganglionic fiber TARGET © 2015 Pearson Education, Inc. Parasympathetic ganglion Table 16-2 A Structural Comparison of the Sympathetic and Parasympathetic Divisions of the ANS. © 2015 Pearson Education, Inc. 16-6 Dual Innervation • Anatomy of Dual Innervation • Parasympathetic postganglionic fibers accompany cranial nerves to peripheral destinations • Sympathetic innervation reaches same structures • By traveling directly from superior cervical ganglia of sympathetic chain © 2015 Pearson Education, Inc. Table 16-3 A Functional Comparison of the Sympathetic and Parasympathetic Divisions of the ANS (Part 1-2 of 4). © 2015 Pearson Education, Inc. Table 16-3 A Functional Comparison of the Sympathetic and Parasympathetic Divisions of the ANS (Part 3-4 of 4). © 2015 Pearson Education, Inc. 16-6 Dual Innervation • Anatomy of Dual Innervation • Autonomic plexuses • Nerve networks in the thoracic and abdominopelvic cavities • Are formed by mingled • sympathetic postganglionic fibers and parasympathetic preganglionic fibers • Travel with blood and lymphatic vessels that supply visceral organs © 2015 Pearson Education, Inc. 16-6 Dual Innervation • Anatomy of Dual Innervation • • • • • • Cardiac plexus Pulmonary plexus Esophageal plexus Celiac plexus Inferior mesenteric plexus Hypogastric plexus © 2015 Pearson Education, Inc. Figure 16-8 The Autonomic Plexuses and Ganglia (Part 1 of 2). Aortic arch Right vagus nerve Autonomic Plexuses and Ganglia Cardiac plexus Pulmonary plexus Thoracic sympathetic chain ganglia Esophageal plexus Celiac plexus and ganglion Superior mesenteric ganglion Inferior mesenteric plexus and ganglia Hypogastric plexus Pelvic sympathetic chain © 2015 Pearson Education, Inc. Figure 16-8 The Autonomic Plexuses and Ganglia (Part 1 of 2). Aortic arch Right vagus nerve Trachea Autonomic Plexuses and Ganglia Cardiac plexus Pulmonary plexus Left vagus nerve Thoracic spinal nerves Esophagus Thoracic sympathetic chain ganglia Esophageal plexus Splanchnic nerves Celiac plexus and ganglion Superior mesenteric ganglion Diaphragm Superior mesenteric artery Inferior mesenteric plexus and ganglia Hypogastric plexus Pelvic sympathetic chain © 2015 Pearson Education, Inc. Inferior mesenteric artery 16-6 Dual Innervation • Autonomic Tone • Is an important aspect of ANS function • If nerve is inactive under normal conditions, can only increase activity • If nerve maintains background level of activity, can increase or decrease activity • Significant where dual innervation occurs • Two divisions have opposing effects • Heart • More important when dual innervation does not occur • Blood vessels © 2015 Pearson Education, Inc. 16-6 Dual Innervation • The Heart Receives Dual Innervation • Two divisions have opposing effects on heart function 1. Parasympathetic division • Acetylcholine released by postganglionic fibers slows heart rate 2. Sympathetic division • NE released by varicosities accelerates heart rate • Balance between two divisions • Autonomic tone is present • Releases small amounts of both neurotransmitters continuously © 2015 Pearson Education, Inc. 16-6 Dual Innervation • The Heart Receives Dual Innervation • Parasympathetic innervation dominates under resting conditions • Crisis accelerates heart rate by: • Stimulation of sympathetic innervation • Inhibition of parasympathetic innervation © 2015 Pearson Education, Inc. 16-6 Dual Innervation • Autonomic Tone • Blood vessel dilates and blood flow increases • Blood vessel constricts and blood flow is reduced • Sympathetic postganglionic fibers release NE • Innervate smooth muscle cells in walls of peripheral vessels © 2015 Pearson Education, Inc. 16-6 Dual Innervation • Autonomic Tone • Background sympathetic tone keeps muscles partially contracted • To increase blood flow: • • • • Rate of NE release decreases Sympathetic cholinergic fibers are stimulated Smooth muscle cells relax Vessels dilate and blood flow increases © 2015 Pearson Education, Inc. 16-7 Visceral Reflexes Regulate the ANS • Visceral Reflexes • Provide automatic motor responses • Can be modified, facilitated, or inhibited by higher centers, especially hypothalamus • Visceral reflex arc • Receptor • Sensory neuron • Processing center (one or more interneurons) • All polysynaptic • Two visceral motor neurons © 2015 Pearson Education, Inc. 16-7 Visceral Reflexes Regulate the ANS • Visceral Reflexes • Long reflexes • Visceral sensory neurons deliver information to CNS • ANS carries motor commands to visceral effectors • Coordinate activities of entire organ • Short reflexes • Bypass CNS • Control simple motor responses with localized effects • One small part of target organ © 2015 Pearson Education, Inc. Figure 16-9 Visceral Reflexes. Receptors in peripheral tissue Afferent (sensory) fibers CENTRAL NERVOUS SYSTEM Stimulus Long reflex Short reflex Processing center in spinal cord Response Peripheral effector Postganglionic neuron © 2015 Pearson Education, Inc. Autonomic ganglion Preganglionic (sympathetic or neuron parasympathetic) 16-7 Visceral Reflexes Regulate the ANS • Visceral Reflexes • Regulating visceral activity • Most organs • Long reflexes most important • Digestive tract • Short reflexes provide most control and coordination © 2015 Pearson Education, Inc. Table 16-4 Representative Visceral Reflexes (Part 1 of 2). © 2015 Pearson Education, Inc. 16-7 Visceral Reflexes Regulate the ANS • The Integration of SNS and ANS Activities • Many parallels in organization and function • Integration at brain stem • Both systems under control of higher centers © 2015 Pearson Education, Inc. Table 16-5 A Comparison of the ANS and SNS. © 2015 Pearson Education, Inc. 16-10 Effects of Aging on the Nervous System • Effects of Aging • Anatomical and physiological changes begin after maturity (age 30) • Accumulate over time • 85 percent of people over age 65 have changes in mental performance and CNS function © 2015 Pearson Education, Inc. 16-10 Effects of Aging on the Nervous System • Reduction in Brain Size and Weight • Decrease in volume of cerebral cortex • Narrower gyri and wider sulci • Larger subarachnoid space • Reduction in Number of Neurons • Brain shrinkage linked to loss of cortical neurons • No neuronal loss in brain stem nuclei © 2015 Pearson Education, Inc. 16-10 Effects of Aging on the Nervous System • Decrease in Blood Flow to Brain • Arteriosclerosis • Fatty deposits in walls of blood vessels • Reduces blood flow through arteries • Increases chances of rupture • Cerebrovascular accident (CVA), or stroke • May damage surrounding neural tissue © 2015 Pearson Education, Inc. 16-10 Effects of Aging on the Nervous System • Changes in Synaptic Organization of Brain • Number of dendritic branches, spines, and interconnections decreases • Synaptic connections lost • Rate of neurotransmitter production declines © 2015 Pearson Education, Inc. 16-10 Effects of Aging on the Nervous System • Intracellular and Extracellular Changes in CNS Neurons • Neurons in brain accumulate abnormal intracellular deposits • Lipofuscin • Granular pigment with no known function • Neurofibrillary tangles • Masses of neurofibrils form dense mats inside cell body and axon © 2015 Pearson Education, Inc. 16-10 Effects of Aging on the Nervous System • Intracellular and Extracellular Changes in CNS Neurons • Plaques • Extracellular accumulations of fibrillar proteins • Surrounded by abnormal dendrites and axons © 2015 Pearson Education, Inc. 16-10 Effects of Aging on the Nervous System • Intracellular and Extracellular Changes in CNS Neurons • Plaques and tangles • Contain deposits of several peptides • Primarily two forms of amyloid ß (Aß) protein • Appear in brain regions specifically associated with memory processing © 2015 Pearson Education, Inc. 16-10 Effects of Aging on the Nervous System • Anatomical Changes • • • • Linked to functional changes Neural processing becomes less efficient with age Memory consolidation more difficult Secondary memories harder to access © 2015 Pearson Education, Inc. 16-10 Effects of Aging on the Nervous System • Sensory Systems • Hearing, balance, vision, smell, and taste become less acute • Reaction times slowed • Reflexes weaken or disappear • Motor Control • Precision decreases • Takes longer to perform © 2015 Pearson Education, Inc. 16-10 Effects of Aging on the Nervous System • Incapacitation • 85 percent of elderly population develops changes that do not interfere with abilities • Some individuals become incapacitated by progressive CNS changes © 2015 Pearson Education, Inc. 16-10 Effects of Aging on the Nervous System • Senility • Also called senile dementia • Degenerative changes • Memory loss • Anterograde amnesia (lose ability to store new memories) • Emotional disturbances • Alzheimer’s disease is most common © 2015 Pearson Education, Inc. 16-10 Nervous System Integration • The Nervous System • Monitors all other systems • Issues commands that adjust their activities • Like conductor of orchestra © 2015 Pearson Education, Inc. 16-10 Nervous System Integration • Neural Tissue • Extremely delicate • Extracellular environment must maintain homeostatic limits • If regulatory mechanisms break down, neurological disorders appear © 2015 Pearson Education, Inc. Figure 16-14 diagrams the functional relationships between the nervous system and other body systems we have studied so far. I N T E G R A T O R Provides calcium ions for neural function; protects brain and spinal cord Controls skeletal muscle contractions that results in bone thickening and maintenance and determine bone position Facial muscles express emotional state; intrinsic laryngeal muscles permit communication; muscle spindles provide proprioceptive sensations Controls skeletal muscle contractions; coordinates respiratory and cardiovascular activities Page 174 Controls contraction of arrector pili muscles and secretion of sweat glands Skeletal Provides sensations of touch, pressure, pain, vibration, and temperature; hair provides some protection and insulation for skull and brain; protects peripheral nerves Integumentary Body System Page 285 Nervous System Muscular Integumentary Skeletal Muscular Nervous System Page 380 S Y S T E M Body System © 2015 Pearson Education, Inc. Page 647 Page 776 Cardiovascular Lymphatic Page 824 Page 874 Respiratory Digestive Page 1090 Page 929 Urinary Page 1010 Reproductive The nervous system is closely integrated with other body systems. Every moment of your life, billions of neurons in your nervous system are exchanging information across trillions of synapses and performing the most complex integrative functions in the body. As part of this process, the nervous system monitors all other systems and issues commands that adjust their activities. However, the significance and impact of these commands varies greatly from one system to another. The normal functions of the muscular system, for example, simply cannot be performed without instructions from the nervous system. By contrast, the cardiovascular system is relatively independent—the nervous system merely coordinates and adjusts cardiovascular activities to meet the circulatory demands of other systems. In the final analysis, the nervous system is like the conductor of an orchestra, directing the rhythm and balancing the performances of each section to produce a symphony, instead of simply a very loud noise. Endocrine The Nervous System