Medical Pharmacology Chapter 4:  Autonomic (ANS) Pharmacology: Introduction

 

• Autonomic Nervous System: Anatomical Considerations

  Figure by Poul-Erik Paulev, M.D., D.Sci, used with permission

• "Thoracolumbar Sympathetic Nervous System (Draw it to Know it)"

  Attribution: Thoracolumbar Sympathetic Nervous System:  Draw it to know it https://www.youtube.com/watch?v=U1aLwYoGjgk . http://www.drawittoknowit.com/ Draw it to Know it - Medical and Biological Sciences Youtube channel https://www.youtube.com/channel/UCDk-BivAYrCbUMwM_xg80xA

   

• "Autonomic Pharmacology"

  Attribution: Saffazadeh A Autonomic Phamacology- Lecture 1 - Intro For Students https://www.youtube.com/watch?v=ju_EYNFRHq8 Areo Saffarzadeh Youtube Channel https://www.youtube.com/channel/UCh93eqkE5oje6973bZXqM8A

• Autonomic and Somatic Innervation

  • Skeletal muscle is innervated by somatic nerves, controlling voluntary actions

  • All other innervated structures are supplied by the autonomic or involuntary system.

  • Somatic system: No ganglia present

  • Autonomic nervous system (ANS) has ganglia.

    • these ganglia are sites at which preganglionic fibers form synaptic connections with postganglionic neurons

    • these ganglia are located outside the cerebrospinal axis

  • Other differences between Somatic and Autonomic Innervation

    • Motor nerves to skeletal muscle: myelinated

    • Postganglionic autonomic nerves are nonmyelinated

    • Denervation of skeletal muscle results in paralysis and atrophy

    • Denervated smooth muscle or glands retain some activity

    • Autonomic Reflex Arc

      • First link: Visceral autonomic afferents to the CNS

        • Non-myelinated, carried to the cerebrospinal axis by autonomic nerves (e.g.vagus and splanchnic)

        • Some autonomic afferents from skeletal muscle blood vessels and integumental structures may be carried in somatic nerves

        • Cell bodies of visceral afferents: (a) spinal nerves--in dorsal root ganglia; (b) cranial nerves-- in sensory ganglia

        • What information gets transmitted?

          • Mediated Information:

            • Visceral sensation (pain; referred pain)

            • Vasomotor reflexes

            • Respiratory reflexes

            • Viscerosomatic reflexes: Definition: Viscerosomatic: Pertaining to the viscera and body

      • Autonomic Reflex Arc: First Link

        Figure by Poul-Erik Paulev, M.D., D.Sci, used with permission

      •  

        "Cardiovascular System:  Control of Heart Rate"

        Attribution:  CTSYouTube:  Cardiovascular system:  control of heart rate CTSYouTube:  https://www.youtube.com/watch?v=PJ8WsZOywgo . October 16, 2012 CTS Youtube Channel: https://www.youtube.com/user/CTSCCCTube/videos

    • Substance P is an important sensory neurotransmitter, probably especially important in nociception, and is found in:

      • Sensory afferent fibers

      • Dorsal root ganglia

      • Dorsal spinal cord horn

    • Other agents found in sensory neurons

      • Somatostatin

      • Vasoactive intestinal peptide (VIP)

      • Cholecystokinin (CCK)

      • Calcitonin gene-related peptide (CGRP) (found with Substance P in cardiovascular sensory nerve fibers)

    • Dorsal Spinal Cord (substantia gelatinosa) Interneurons

      • Enkephalins: Antinociceptive due to inhibition of substance P release and reduced transmission to higher centers

  • CNS and the Autonomic Nervous System

    • Spinal Cord Reflexes

      • Sweating

      • Blood pressure changes

      • Temperature-induced changes in vasomotor tone

      • Emptying of the bowels, bladder, seminal vesicles

    •  Hypothalamic and Nucleus tractus solitarii

      • Integration of ANS Functions

        • Body temperature regulation

        • Emotions

        • Water balance

        • Sexual response

        • Fat/carbohydrate metabolism

        • Sleep

        • Blood pressure

        • Respiration

    • Higher Centers

      • Posterior and Lateral Hypothalamic Nuclei are associated with integration of autonomic sympathetic input

      • Midline nuclei in the region of the Tuber cinereum and anterior nuclei Nuclei are associated with integration of autonomic parasympathetic input

    • Peripheral ANS: Divisions

      • Sympathetic: (Thoracolumbar outflow)

      • Parasympathetic; (Craniosacral Outflow)

    • Autonomic Nervous System Neurotransmitters: Summary

      • Neurotransmitter: Acetylcholine

        • All preganglionic autonomic fibers

        • Parasympatheticfibers

        • A few post-ganglionic sympathetic fibers

      • Neurotransmitter: Norepinephrine

        • Postganglionic Sympathetic Fibers

      • Neurotransmitter: Primary Afferents:  Substance P and/or glutamate

     

    Lefkowitz, R.J, Hoffman, B.B and Taylor, P. Neurotrasmission: The Autonomic and Somatic Motor Nervous Systems, In, Goodman and Gillman's The Pharmacologial Basis of Therapeutics, (Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) TheMcGraw-Hill Companies, Inc.,1996, pp.105-107.