Visual Anatomy & Physiology First Edition Martini & Ober Chapter 14 Autonomic Nervous System Lecture 21 1 Autonomic (Visceral) Nervous System CNS PNS 2 Autonomic Nervous System functions without conscious effort controls visceral (squishy!) activities regulates smooth muscle, cardiac muscle, and glands Two Main Divisions sympathetic prepares body for fight or flight situations parasympathetic prepares body for rest and digest activities Third Division Enteric Nervous System (ENS) 3 1
Somatic vs. Autonomic Nervous Systems Dual Figure from: Marieb, Human Anatomy & Physiology, Pearson Education, 2004 4 Autonomic Nerve Fibers ANS = a motor division of the PNS 5 Sympathetic Division of ANS Paravertebral ganglion Effectors in head and thoracic cavity Effectors in muscles and body wall (T5 T12) Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007 6 2
Sympathetic Division of the ANS SYMPATHETIC (Thoracolumbar outflow) Fight or Flight E situations Emergency Embarrassment Excitement Exercise Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 8 Spinal Nerves Autonomic Fibers Sympathetic ganglion - cell bodies of postganglionic sympathetic neurons Three fates of a preganglionic sympathetic axon: 1) synapse in same chain ganglion 2) Ascend/descend to synapse in another chain ganglion 3) Pass through without synapsing (form prevertebral, or collateral ganglia) Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004 9 Sympathetic Division - Divergence NOTE: Arrangement of nerves creates DIVERGENCE Sympathy spreads 11 3
Parasympathetic (Craniosacral outflow) REST AND DIGEST Salivation Lacrimation Urination Digestion Defecation 3 decreases - Heart rate - Airway diameter - Pupil size (constrict) Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004 12 Spinal Nerves Visceral Sensory Fibers Dorsal root - axons of sensory neurons in the dorsal root ganglion Dorsal root ganglion - cell bodies of sensory neurons Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004 13 Autonomic Plexuses Sympathetic collateral (prevertebral) ganglia Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004 14 4
Autonomic Neurotransmitters = always excitatory in ganglia You should know which neurotransmitters are released, and the locations where they are released 15 Sympathetic Myoneural Junctions NE is either: - reabsorbed and reused or broken down by monoamine oxidase (MAO) in varicosities - or broken down by catechol-omethyltransferase (COMT) in surrounding tissues Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004 16 Actions of Autonomic Neurotransmitters depend on receptor Cholinergic receptors bind acetylcholine nicotinic excitatory muscarinic excitatory or inhibitory Adrenergic receptors bind norepinephrine alpha (Types 1 and 2) different responses on various effectors beta (Types 1 and 2) different responses on various effectors 17 5
Actions of Cholinergic Receptors Cholinergic receptors Nicotinic receptors always excitatory Muscarinic Excitatory or inhibitory Remember: the (Sweat glands, blood vessels to skeletal muscles, brain) RECEPTOR determines the effect of a neurotransmitter Always excitatory 18 Control of Autonomic Activity Sympathetic and Parasympathetic Sympathetic Parasympathetic Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 19 Review The autonomic nervous system (ANS) Controls visceral activities involuntarily Sympathetic (thoracolumbar) = fight or flight Parasympathetic (craniosacral) = rest and digest Efferent fibers synapse in ganglia outside CNS NTx of the ANS Acetylcholine (cholinergic) pre- and postganglionic parasympathetic and preganglionic sympathetic Adrenergic (norepinephrine) postganglionic sympathetic ONLY 20 6
Review Branch of ANS PARASYMPATHETIC SYMPATHETIC General Function Origin of Preganglionic fiber Length of Preganglionic fiber Location of Ganglia NTx secreted by postganglionic fiber rest and digest (SLUDD; 3 decreases) from cranial region of brain or sacral region of spinal cord (craniosacral outflow) long within or near effector acetylcholine fight or flight ( E situations) from thoracic or lumbar region of spinal cord (thoracolumbar outflow) short Know this chart alongside or in front of spinal cord Norepinephrine (some acetylcholine; sweat glands, smooth muscle on blood vessels, brain) 21 7