Autonomic Nervous System Introduction PDF

Pharmacotherapeutics I (PTH1) Autonomic Nervous System (Introduction) Dr. Nagwan Shanan Assistant Prof. of Pharmacology Dr. Chris Benham Sep 2020 1 Intended Learning Outc...

Pharmacotherapeutics I (PTH1) Autonomic Nervous System (Introduction) Dr. Nagwan Shanan Assistant Prof. of Pharmacology Dr. Chris Benham Sep 2020 1 Intended Learning Outcome Recall the anatomy and function of the autonomic nervous system. Discuss the effect of the sympathetic and parasympathetic nervous system within the body. Identify the different types of autonomic receptors. The Nervous System (Recap) Peripheral nervous system CNS Afferent Efferent Somatic nervous system Autonomic nervous system Parasympathetic nervous system Sympathetic nervous system **The enteric nervous system Divisions of the ANS Sympathetic: - FIGHT or FLIGHT (activity increases in stressful conditions) - Mass Discharge - Neurotransmitter (Noradrenaline) Parasympathetic: - REST and DIGEST (activity dominates during rest) - Discrete Actions - Neurotransmitter (Acetylcholine) Autonomic Equilibrium (Recap) Sympathetic Parasympathetic ANS Anatomy (Recap) Sympathetic Parasympathetic Vagus nerve  ANS Anatomy (Recap) ANS is an efferent pathway consisting of a two neuron chain Adapted from Human Physiology Cells to Systems (7th Ed.) Sherwood L. Autonomic Nervous System (Recap) Basic structure, neurotransmitters and receptors of the ANS Ach = Acetylcholine NA = Noradrenaline A = Adrenaline N = Nicotinic M = Muscarinic α = Alpha adrenergic Β = Beta adrenergic ANS Functions By recalling the functions of both parasympathetic and sympathetic branches on each organ, it is possible to explain action and adverse effects of many drugs. = stimulation = inhibition 9 Autonomic Receptors G protein coupled receptors: Gs / Gi Sep 2020 10 Autonomic Receptors G protein coupled receptors: Gq e.g. muscle contraction Sep 2020 11 Autonomic Receptors G0 G protein coupled Gi Receptors Ligand Gs Gq G protein Enzyme Ion channel G0 Adenylate cyclase (AC) Phospholipase C activation (Gq) *(Gi) inhibition of AC decrease cAMP level and decrease IP3 ( increase the calcium level in tissue) the activation of PKA DAG (activation of PKC) *(Gs) stimulation of AC cAMP, IP3 & DAG (2o messengers) increase cAMP level and increase the activation of PKA Autonomic Receptors Ligand gated ion channel e.g. Nicotinic receptors Predominant Na+ influx Excitatory effects Depolarization Sympathetic receptors (Adrenoreceptors) GPCRS Excitatory & Inhibitory Effects 14 Parasympathetic receptors (Cholinoreceptors) GPCRS Excitatory & Inhibitory Effects 15 Therapeutic Agents Drugs Acting on the Autonomic Nervous System Parasympathetic NS Sympathetic NS Muscarinic Agonists α and β receptors agonists (effect similar to activation of (effect similar to activation of SNS) PNS) α and β receptors blockers Muscarinic Antagonists (reduces the activity of SNS (reduces the activity of PNS leading to PNS predominance) leading to SNS predominance) 16 References Rang & Dale’s Pharmacology (2019). 9th Ed. Elsevier. Section 2:12 (The autonomic nervous system) 17