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AUTONOMIC NERVOUS SYSTEM

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AUTONOMIC NERVOUS SYSTEM

  1. 1. AUTONOMIC NERVOUS SYSTEM DR NILESH KATE MBBS,MD ASSOCIATE PROF ESIC MEDICAL COLLEGE, GULBARGA. DEPT. OF PHYSIOLOGY
  2. 2. OBJECTIVES  Anatomical consideration.  Divisions.  General organization.  The Sympathetic Division  The Parasympathetic Division.  Physiological consideration.  Neurotransmitters & receptors.  Functions of ANS.  Relationships Between the Sympathetic and Parasympathetic Divisions  Applied physiology
  3. 3. ORGANIZATION OF THE NERVOUS SYSTEM BRAIN SPINAL CORD CENTRAL NERVOUS SYSTEM (CNS) PERIPHERAL NERVOUS SYSTEM AFFERENT NERVES EFFERENT NERVES EXTERO-RECEPTORS INTERO-RECEPTORS SOMATIC AUTONOMIC EFFECTOR ORGANS SKELETAL MUSCLES SMOOTH AND CARDIAC MUSCLES AND GLANDS
  4. 4. Autonomic Nervous System (ANS)  Derived from Greek word “autos – self & nomos – control”  An involuntary nervous system that modulates and controls the function of visceral organs.  Since it controls vegetative functions also called as vegetative system.
  5. 5. Divisions of the ANS  2 divisions:  Sympathetic :  (fight or flight)  Parasympathetic :  Controls daily body functions  Both divisions are constantly “counteracting” or acting together in “autonomic tone”
  6. 6. Autonomic Nervous System (ANS) Thursday, December 11, 2014
  7. 7. SOMATIC & AUTONOMIC NERVOUS SYSTEM. SOMATIC  Afferent neuron terminate in dorsal horn.  Interneuron terminates in ventral horn.  Efferent neuron cell body in ventral horn.  Single efferent neuron  Innervates skeletal muscles.  Neurotransmitter – Ach  Activity – excitation.  Always voluntary. ANS  Afferent neuron terminate in intermediolateral horn.  Interneuron terminates in autonomic ganglia.  Efferent neuron cell body in autonomic ganglia.  2 efferent neurons.  Innervates smooth muscle, cardiac muscle , secretory glands.  Neurotransmitter – Ach & NE.  Activity – Excitation & inhibition.  Usually Involuntary. Thursday, December 11, 2014
  8. 8. Thursday, December 11, 2014
  9. 9. GENERAL ORGANIZATION.  Autonomic areas in cerebral hemisphere.  Autonomic centers in brain stem.  Autonomic centers in spinal cord.  Peripheral part of ANS. Thursday, December 11, 2014
  10. 10. Autonomic areas in cerebral hemisphere.  Limbic system.  Prefrontal cortex.  Hypothalamus.  Integration of somatic, autonomic & endocrine functions.  Main ganglion of ANS.  LIMBIC CORTEX equally important.  Thalamus. Thursday, December 11, 2014
  11. 11. Autonomic centers in brain stem.  Reticular formation.  Gigantocellular nucleus.  Parvocellular nuclei.  Visceral nuclei of cranial nerves. Thursday, December 11, 2014
  12. 12. Visceral nuclei of cranial nerves.  Afferent nucleus.  Nucleus of solitary tract in medulla.  Receives through IX & X.  Along with reticular formation reflex control of RS & CVS function.  Efferent nucleus.  Preganglionic fibres of parasympathetic craniosacral outflow.  Includes- (DES).  Dorsal nucleus of vagus.  Edinger-vestphal N.  Salivary nucleus. Thursday, December 11, 2014
  13. 13. Autonomic centers in spinal cord.  Intermediolateral grey column of spinal cord.  2 levels.  Sympathetic – T-1 to L-3  Parasympathetic – cranial part - S-2 to S-4. Thursday, December 11, 2014
  14. 14. Peripheral part of ANS.  All autonomic nerves & ganglia.  No nerve in the body is totally autonomic. Thursday, December 11, 2014
  15. 15. Neurons of ANS  PREGANGLIONIC NEURON  cell body in brain or spinal cord  axon is myelinated type B fiber that extends to autonomic ganglion  POSTGANGLIONIC NEURON  cell body lies outside the CNS in an autonomic ganglion  axon is unmyelinated type C fiber that terminates in a visceral effector
  16. 16. Physiological Effects of the ANS Hypothalamus  only sympathetic innervations  sweat glands, adrenal medulla, erector pili & many blood vessels  controlled by regulation of the “tone” of the sympathetic system  Rest receive dual innervations  Hypothalamus .
  17. 17. Sympathetic motor ANS  Thoracolumber outflow  3 destinations.  Terminate in the ganglia.  Travel up & down & then terminate.  Pass without synapsing & terminate in prevertebral ganglia.
  18. 18. SYMPATHETIC GANGLIA  The ganglia of sympathetic division are classified into three groups. Para vertebral or sympathetic chain ganglia Prevertebral or collateral ganglia Terminal or peripheral ganglia
  19. 19. SYMPATHEIC GANGLIA. Thursday, December 11, 2014 A B C-4 C-1 A-1 C-2 A-2 A-3 B-1 B-2 B-3 C-3
  20. 20. Sympathetic motor NS  Lateral horn  paravertebral ganglia  spinal nerve = white communicating ramus (myelinated)  Signals from the ganglion (to the target tissue) travel along unmyelinated fibers = grey communicating ramus  Signals between ganglia along the sympathetic trunk
  21. 21. PARASYMPATHETIC DIVISION otherwise called craniosacral outflow because, the fibers of this division arise from brain and sacral segments of spinal cord The cranial nerves of the parasympathetic division are: 1. Oculomotor (III) nerve 2. Facial (VII) nerve 3. Glossopharyngeal (IX) nerve 4. Vagus(X)nerve) 3. Sacral outflow (sacral nerves)
  22. 22. PARASYMPATHETIC SPINE EFFECTOR ORGAN PARASYMPATHETIC GANGLIA (NEAR EFFECTOR ORGAN)
  23. 23. TECTAL OR MIDBRAIN LEVEL  The group of cells forming Edinger-Westphal nucleus of Ill cranial nerve gives rise to tectal fibers.  The fibers from this nucleus end in the ciliary ganglion.  The postganglionic fibers from here supply the sphincter pupillae and ciliary muscIe
  24. 24. MIDBRAIN OR TECTAL OUTFLOW. & BULBAR OUTFLOW. Thursday, December 11, 2014
  25. 25. Autonomic neurotransmitters. Thursday, December 11, 2014
  26. 26. Cholinergic receptors. Thursday, December 11, 2014
  27. 27. Adrenergic receptors. Alpha receptors.(α)  α - 1 (VGR)  Vascular smooth muscles of skin & splanchnic region  GIT & bladder sphincters  Radial muscles of Iris.  α -- 2 ( PPFW)  Presynaptic nerve terminal  Platelets  Fat cells  Walls of GIT. Thursday, December 11, 2014
  28. 28. Adrenergic receptors. Beta receptors.(β)  β -- 1 ( SAV)  SA node  AV node  Ventricular muscles of heart.  β – 2 (VBWB)  Vascular smooth muscles of skeletal muscles  Bronchial smooth muscle  Walls of GIT  Bladder.  β – 3 Thursday, December 11, 2014
  29. 29. Differences in Sympathetic and Parasympathetic Divisions
  30. 30. Comparison of some effects of sympathetic & parasympathetic branches SSyymmppaatthheettiicc nneerrvvoouuss ssyysstteemm PPaarraassyymmppaatthheettiicc nneerrvvoouuss ssyysstteemm iinnccrreeaasseess ccaarrddiiaacc oouuttppuutt ddeeccrreeaasseess ccaarrddiiaacc oouuttppuutt iinnccrreeaasseess bblloooodd pprreessssuurree ddeeccrreeaasseess bblloooodd pprreessssuurree ddiillaatteess bbrroonncchhiioolleess ccoonnssttrriicctt bbrroonncchhiioolleess iinnccrreeaasseess vveennttiillaattiioonn rraattee ddeeccrreeaasseess vveennttiillaattiioonn rraattee ddiillaatteess ppuuppiillss ccoonnssttrriicctt ppuuppiill
  31. 31. Comparison of some effects of sympathetic & parasympathetic branches SSyymmppaatthheettiicc nneerrvvoouuss ssyysstteemm PPaarraassyymmppaatthheettiicc nneerrvvoouuss ssyysstteemm ccoonnttrraaccttss aannaall && bbllaaddddeerr sspphhiinncctteerrss rreellaaxxeess aannaall && bbllaaddddeerr sspphhiinncctteerrss ccoonnttrraaccttss eerreeccttoorr ppiillii mmuusscclleess nnoo ccoommppaarraabbllee eeffffeecctt iinnccrreeaasseess sswweeaatt pprroodduuccttiioonn nnoo ccoommppaarraabbllee eeffffeecctt nnoo ccoommppaarraabbllee eeffffeecctt iinnccrreeaasseess sseeccrreettiioonn ooff tteeaarrss
  32. 32. Autonomic Reflexes Cardiovascular: - baroreceptor reflex: It is stretch reflex in the main arteries such as carotid artery to detect the blood pressure  Gastrointestinal: The receptors in the nose and mouth send a signal to parasympathetic to notify the glands of mouth & stomach to secrete the digestive juices
  33. 33. Autonomic Reflexes  Urinary Bladder: - Initiate the micturation by parasympathetic innervations  Sexual reflexes: - erection by parasympathetic - ejaculation by sympathetic  The sympathetic activation often occurs in a mass discharge such as in fright or severe pain “fight or fright”(sympathetic stress response)
  34. 34. Functions of ANS  Mediate neuronal regulation of internal environment  Coordinate bodily function necessary for survival  Regulate removal of waste products from the body  Prepare the body for normal and life-threatening stress  Effected via control over smooth and heart M. and glands  “autonomic” = self-governing
  35. 35. The Race Horse and the Cow Sympathetic Parasympathetic
  36. 36. Thursday, December 11, 2014
  37. 37. Sympathetic Nervous System (SNS)  Operates continuously to modulate the functions of many organ systems e.g; heart, blood vessels, GIT, bronchi and sweat glands  Stressful stimulation activates SNS leads to a response known as “fight or flight”: increased arterial pressure, blood flow, blood glucose, metabolic rate and mental activity
  38. 38. Thursday, December 11, 2014
  39. 39. Applied aspects.  Autonomic drugs.  Autonomic failure.  Autonomic function tests. Thursday, December 11, 2014
  40. 40. Autonomic drugs.  Mimetic  Lytic or Blockers.  So……………..  Sympathomimetic  Sympatholytic  Parasympathomimetic  Parasympatholytic. Thursday, December 11, 2014
  41. 41. SYMPATHOMIMETIC DRUGS  Directly acting.  Act directly on alpha & beta adrenergic receptors.  E.g.—  Adrenaline  Nor adrenaline  Phenylnephrine.  Indirectly acting. (enhancing action of NE)  displacing NE from storage sites. – amphetamine.  Inhibiting reuptake. – imipramine.  MAO inhibitors. Thursday, December 11, 2014
  42. 42. SSYYMMPPAATTHHEETTIICC BBLLOOCCKKEERRSS  Prevention of synthesis & storage of NE. – Reserpine.  Prevention of release of NE. – Guanethidine.  Blockage of receptors.  Alpha -- Phentolamine  Beta – Propranolol, Metoprolol.  Blockage of transmission of nerve impulse. – Hexamethonium. Thursday, December 11, 2014
  43. 43. Parasympathomimetic drugs.  Drugs acting on muscarinic receptors. – Pilocarpine, Methacholine.  Prolonging action of Ach –Neostigmine, Physostigmine. Thursday, December 11, 2014
  44. 44. Parasympathetic blockers.  Drugs blocking Muscarinic receptors.  Atropine  Homatropine  Scopolamine. Thursday, December 11, 2014
  45. 45. Autonomic failure.  Primary  Cause not known.  Autonomic neuronal degeneration.  Secondary  Secondary to some cause.  Most common cause.--Diabetes mellitus. Thursday, December 11, 2014
  46. 46. Autonomic failure.  Features.  CVS – Orthostatic hypotension , tachycardia.  Sudomotor – anhidrosis, heat intolerance.  GIT – constipation , diarrhea & dysphagia.  Urinary – nocturia, frequency, urgency, incontinence & retention.  Reproductive – erectile & ejaculation failure. Thursday, December 11, 2014
  47. 47. Disorders of the Autonomic Nervous System: Raynaud’s Disease  Raynaud’s disease – characterized by constriction of blood vessels  Provoked by exposure to cold or by emotional stress
  48. 48. Disorders of the Autonomic Nervous System: Hypertension  Hypertension – high blood pressure Can result from overactive sympathetic vasoconstriction
  49. 49. Disorders of the Autonomic Nervous System: Achalasia of the Cardia MMaassss rreefflleexx rreeaaccttiioonn  UUnnccoonnttrroolllleedd aaccttiivvaattiioonn ooff aauuttoonnoommiicc aanndd ssoommaattiicc mmoottoorr nneeuurroonnss  AAffffeeccttss qquuaaddrriipplleeggiiccss aanndd ppaarraapplleeggiiccss  Achalasia of the cardia  Defect in the autonomic innervation of the esophagus
  50. 50. Autonomic function tests.  Cardiovascular  Pupillary  Sudomotor.  Bladder. Thursday, December 11, 2014
  51. 51. Autonomic function tests.  Cardiovascular.  Valsalva manoeuvre.  Heart rate variation during deep breathing.  Heart rate response to standing.  blood pressure response to standing.  Blood pressure response to sustained handgrip.  Sudomotor.  Evaluation of sweating response to increased body temperature. Thursday, December 11, 2014
  52. 52. Autonomic function tests.  Pupillary function.  Cocaine test. Normal pupil dilate Horner’s pupil – not  Adrenaline test. Horner’s pupil dilate more than normal.  Bladder function  Absense of accommodation.  Absense or poor voluntary bladder contraction. Thursday, December 11, 2014
  53. 53. RECAP  Anatomical consideration.  Divisions.  General organization.  The Sympathetic Division  The Parasympathetic Division.  Physiological consideration.  Neurotransmitters & receptors.  Functions of ANS.  Relationships Between the Sympathetic and Parasympathetic Divisions  Applied physiology
  54. 54. Thank You

Hinweis der Redaktion

  • The ANS is one of the most sophisticated control systems known to man. It is primarily involved in maintaining the homeostatic state of the organism while allowing adaptation to changes in conditions, sometimes even severe changes.
    Contrary to the somatic division of the CNS is it a totally unconscious activity. It also involves a sophisticated interplay of chemical and neural signals (see previous lecture).
  • The parasympathetic ganglia are near the effector organ.

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