21/10/20151 Autonomic Nervous System

Aims of session To review the basic structure and function of the Autonomic Nervous System (ANS)

Objectives Learners should be able to: 1.Describe the basic structure and general functions of the sympathetic and parasympathetic divisions of the autonomic nervous system 2.Describe the fight’/’flight’ responses and cooperative effects of the sympathetic and parasympathetic sysyem on different organs.

Nervous System Divisions Anatomical division of Nervous system Central Nervous System (Brain, Spinal Cord) Peripheral Nervous System (Nerve connections between the CNS and body organs/tissues ) 21/10/20154 Encased in the Cranium and vertebral column allows nerve connections between the CNS and the organs and tissues of the body i.e. the nerve trunks, plexus and nerve fibres

Nervous System - Physiology Physiological division of the nervous system Somatic Voluntary and Conscious Mechanisms Autonomic Involuntary Control Mechanisms Sympathetic and Parasympathetic 21/10/ E.G Skeletal muscle and joint movement Regulating: Cardiorespiratory, Gastrointestinal, Genitourinary Reproductive, Integumentary Neurological, Endocrine systems

21/10/20156 Ganglia- e.g.. Part of the nervous system that carries out its functioning automatically i.e. without conscious control. With such organs and tissue are able to function in either a decreased or increased manner in order to maintain homeostasis

Ganglion A mass of nerve cell bodies RECAP Dorsal root ganglia – sensory nerves connect CNS with PNS Autonomic Ganglia Autonomic ganglia -clusters of neurones and a junction between autonomic nerves originating from the CNS and autonomic neurones serving peripheral target organs. CNS to ganglia = Preganglionic Ganglia to effector organ = Postganglionic Many sympathetic and parasympathetic ganglions run from the top to the bottom of the spine. 21/10/2015:

21/10/ Physiological Similarities and Differences Sympathetic nerve type Myelinated / Unmyelinated Distribution Neurotransmitter (normally) Function Preganglionic MyelinatedCNS to Ganglion Acetylcholine Fight’ or ‘Flight’ response Postganglionic Unmyelinated.Throughout body Noradrenaline. Parasympathetic nerve type Myelinated / Unmyelinated Distribution Neurotransmitter (normally) Function PreganglionicMyelinated CNS to Ganglion Acetylcholine returns body to normal state after a fight/flight PostganglionicUnmyelinated. Throughout body acetylcholine. Postganglionic fibres i.e. between the Ganglion and target tissue ganglion) Preganglionic fibres i.e. between the CNS and the ganglion anglionic fibres i.e. between the Ganglion and target tissue ganglion)

What would be happening to an arteriole with sympathetic nerve stimulation? What would be happening to the Gut wall with parasympathetic nerve stimulation?

Sympathetic Inhibitory and Excitatory Functions 2 types of receptors to Sympathetic nerve excitation - Alpha and Beta Adrenaline excites both alpha and beta receptors equally Noradrenaline excites mainly alpha receptors. There are also subtypes of each – more of this later on 21/10/201513

Autonomic Nervous System Effects StructureSympathetic StimulationParasympathetic Stimulation Iris (eye muscle)Pupil DilationPupil Constriction Salivary GlandsSaliva production reducedSaliva production increased Oral/Nasal Mucosa Mucus production reducedMucus production increased Heart Heart rate and force increased Heart rate and force decreased LungBronchial muscle relaxedBronchial muscle contracted StomachPeristalsis reduced Gastric juice secreted; motility increased Small IntestineMotility reducedDigestion increased Large IntestineMotility reducedSecretions and motility increased Liver Increased conversion of glycogen to glucose Reduction in conversion of glycogen to glucose KidneyDecreased urine secretionIncreased urine secretion Adrenal medulla Noradrenaline and adreanaline secreted Secretion of Adrenaline and noradrenalin Bladder Wall relaxed Sphincter closed Wall contracted Sphincter relaxed

Organ Sympathetic Stimulation Parasympathetic Stimulation Heart Increased heart rate beta 1 (& beta 2 )Decreased heart rate Increased force of contraction beta 1 (& beta 2 ) Decreased force of contraction Increased conduction velocityDecreased conduction velocity Arteries Constriction (alpha 1 ) Dilation Dilation (beta 2 ) Veins Constriction (alpha 1 ) Dilation (beta 2 ) LungsBronchial muscle relaxation (beta 2 ) Bronchial muscle contraction Increased bronchial gland secretions GastroIntestinal tract tract Decreased motility (beta 2 )Increased motility Contraction of sphincters (alpha)Relaxation of sphincters Major Organ Responses to Autonomic Impulses

Liver Glycogenolysis (beta 2 & alpha) Glycogen synthesis Gluconeogenesis (beta 2 & alpha) Lipolysis (beta 2 & alpha) KidneyRenin secretion (beta 2 ) Bladder Detrusor relaxation (beta 2 )Detrusor contraction Contraction of sphincter (alpha)Relaxation of sphincter Uterus Contraction of pregnant uterus (alpha) Relaxation of pregnant and non- pregnant uterus (beta 2 ) EyeDilates pupil (alpha) Constricts pupil Increased lacrimal gland secretions Submandibular & parotid glands Viscous salivary secretions (alpha)Watery salivary secretions Major Organ Responses to Autonomic Impulses Organ Sympathetic Stimulation Parasympathetic Stimulation SkinPilomotor muscles contract Sweat glands secrete slightly