Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Pharmacology of Drugs Affecting Autonomic Nervous System

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Lecture 9 Introduction to autonomic nervous system

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Autonomic Pharmacology  Introduction to Nervous System  Classification of Nervous System  Somatic Vs Autonomic  Sympathetic Vs Parasympathetic  Dominant Tone

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Basic Functions of the Nervous System  Recognizing changes in  Internal environment  External environment  Processing and integrating environmental changes  Reacting to environmental changes by producing an action or response

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Two Major Divisions of the Nervous System  Central Nervous System (CNS)  Brain and spinal cord  Peripheral Nervous System  all nervous tissues outside the CNS, including sensory and motor neurons

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Divisions of human nervous system Human Nervous system Central Nervous System Peripheral Nervous System

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Brain & Spinal Cord Nerves enter or leave CNS Carry massage from CNS to peripheral tissues Carry massage from peripheral tissues to CNS

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Divisions of the Peripheral Nervous System  Somatic nervous system  Voluntary control over skeletal muscles  Autonomic nervous system  Involuntary control over smooth and cardiac muscle and glands

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Autonomic Pharmacology  Autonomic Nervous System  This system is divided into two separate systems.  These systems are called the parasympathetic nervous system and the sympathetic nervous system.  These systems often produce opposite effects, but b ranches do not always produce opposite effects.  Homeostasis – proper balance of the two branches achieved by changing one or both branches 2

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Autonomic Nervous System: Sympathetic and Parasympathetic Divisions  Drugs in this group are designed to either enhance or mimic the autonomic nervous system or to block the effects of the neurotransmitters at their receptor sites.

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Steps of Neurotransmission  Propagation of the nerve impulse in the preganglionic nerve fiber Polarized Resting Membrane Potential Depolarized Nerve Action Potential

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Synaptic Transmission  Synapse – junction of neurons  Connection of two neurons outside CNS – ganglionic synapse.

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Efferent neurons  Preganglionic neurons: Cell body within CNS Cell body within CNS  Ganglia: aggregation of nerve cell bodies located in the peripheral nervous system.  Postganglionic neurons: cell body originate in the ganglia, terminates on effector organ.  Divided into sympathatic and parasympathatic

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Figure 13.4 Receptors in the autonomic nervous system: (a) sympathetic division; (b) parasympathetic division

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Role of CNS in autonomic control functions  CNS centers in hypothalamus, medulla oblongata & spinal cord  Reflex arc  Emotions

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Organs Supplied by ANS  Heart  Smooth Muscles - Eye -Bronchi - GIT - Urinary Bladder - Blood Vessels  Glands - Exocrine Glands: Lacrymal, Salivary, Sweat - Endocrine Glands: Adrenal Medulla  Metabolism  Liver  Adipose Tissue  Kidney

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Basic anatomy of ANS Sympathetic NSParasympathetic NS Enteric NS Two main differences - Origin - Function -Collection of nerve fibers that innervate GIT, pancrease & gall bladder -Called “brain of gut” -They control motility, exocrine & endocrine secretion, as well as microcirculation of gut -Modulated by sympathatic & Parasympathatic systems

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Origin Symp. NS Thoracolumbar outflow Parasymp. NS Function Craniosacral outflow Short pre-ganglionic nerve Long post-ganglionic nerve Long pre-ganglionic nerve Short post-ganglionic nerve

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Sympathetic Nervous System  Sympathetic Nervous System  This nervous system is designed to cope with emergency situations.  This is commonly known as the “fright or flight” response.  Its neurotransmitters are epinephrine and norepinephrine.  Its receptors are the α and β receptors. 4

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Sympathetic nervous system Fight or flight response results in: 1. Increased BP 2. Increased blood flow to brain, heart and skeletal muscles 3. Increased muscle glycogen breakdown for energy 4. Increased rate of coagulation 5. Pupil dilation

parasympathatic Nervous System  Parasympathetic Nervous System  This system is concerned with the conservation of the body processes.  Activated under non stressful conditions  Rest-and-digest response  Digestive processes promoted, heart rate and blood pressure decline  Its main neurotransmitter is acetylcholine.  Its receptors are muscarinic, nicotinic. 3

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Figure 13.2 Effects of the sympathetic and parasympathetic nervous systems. Source: Biology Guide to the Natural World, 2 nd ed (p. 558) by David Krogh, 2002 Upper Saddle River, NJ, Prentice Hall. Reprinted by permission.

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Symp. NS Parasymp. NS Single Innervations Dilator pupilae muscle Adrenal Medulla Ventricles BV Sweat Gland Kidney Constrictor pupillae muscle

Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Sympathetic nervous system neurotransmitters ACH dopamine norepinephrine