Transcript Document
Anatomy and Physiology, Sixth Edition Rod R. Seeley Idaho State University Trent D. Stephens Idaho State University Philip Tate Phoenix College Chapter 16 Lecture Outline* *See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 16-1 Chapter 16 Autonomic Nervous System 16-2 Somatic and Autonomic Nervous System Somatic • Skeletal muscle • Conscious and unconscious movement • Skeletal muscle contracts • One synapse • Acetylcholine Autonomic • Smooth and cardiac muscle and glands • Unconscious regulation • Target tissues stimulated or inhibited • Two synapses • Acetycholine by preganglionic neurons and ACh or norepinephrine by postganglionic neurons 16-3 Sympathetic Division • Preganglionic cell bodies in lateral horns of spinal cord T1-L2 • Preganglionic axons pass through ventral roots to white rami communicantes to sympathetic chain ganglia – Four routes possible • • • • Spinal nerves Sympathetic nerves Splanchnic nerves Innervation to adrenal gland 16-4 Routes by Sympathetic Axons 16-5 Parasympathetic Division • Preganglionic cell bodies in nuclei of brainstem or lateral parts of spinal cord gray matter from S2-S4 – Preganglionic axons from brain pass to ganglia through cranial nerves – Preganglionic axons from sacral region pass through pelvic nerves to ganglia • Preganglionic axons pass to terminal ganglia within wall of or near organ innervated 16-6 Enteric Nervous System • Consists of nerve plexuses within wall of digestive tract – Sources • Sensory neurons that connect the digestive tract to CNS • ANS motor neurons that connect CNS to digestive tract • Enteric neuron which are confined to enteric plexuses 16-7 Distribution of ANS Fibers • Sympathetic axons reach organs through – Spinal nerves – Head and neck nerve plexuses – Thoracic nerve plexuses – Abdominopelvic nerve plexuses • Parasympathetic axons reach organs through – Cranial nerves – Thoracic nerve plexuses – Abdominopelvic nerve plexuses – Pelvic nerves 16-8 Physiology of ANS • Neurotransmitters – Acetylcholine released by cholinergic neruons – Norepinephrine released by adrenergic neurons • Receptors – Cholinergic • Nicotinic and muscarinic – Adrenergic • Alpha and beta receptors 16-9 Location of ANS Receptors 16-10 Regulation of ANS • Autonomic reflexes control most of activity of visceral organs, glands, and blood vessels • Autonomic reflex activity influenced by hypothalamus and higher brain centers • Sympathetic and parasympathetic divisions influence activities of enteric nervous system through autonomic reflexes – Enteric nervous system can function independently of CNS through local reflexes 16-11 Autonomic Reflexes 16-12 Influence of Brain on Autonomic Functions 16-13 Functional Generalizations of ANS • Stimulatory versus inhibitory effects – Both divisions of ANS • Dual innervation – Most organs innervated by both • Either division alone or both working together can coordinate activities of different structures • Sympathetic produces more generalized effects – Prepares body for physical activity or flight-or-fight response • Parasympathetic more important for resting conditions – SLUDD: Salivation, lacrimation, urination, digestion, defecation 16-14 “Fight-or-Flight” Responses • Increased heart rate and force • Blood vessel dilation in skeletal and cardiac muscles • Dilation of air passageways • Energy sources availability increased – Glycogen to glucose – Fat cells break down triglycerides • Muscles generate heat, body temperature increases • Sweat gland activity increases • Decrease in nonessential organ activities 16-15