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PHYSIOLOGY OF AUTONOMIC NERVOUS SYSTEM

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PHYSIOLOGY OF ANS(AUTONOMIC NERVOUS SYSTEM)
Sympathetic Responses
Parasympathetic Responses
Autonomic Interactions
Control of Autonomic Nervous System Function

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PHYSIOLOGY OF AUTONOMIC NERVOUS SYSTEM

  1. 1. Physiology of autonomic nervous system Lecture 6 Text PHYSIOLOGY OF AUTONOMIC NERVOUS SYSTEM
  2. 2. Questions 1. ANS structural and functional organization 2. Autonomic ganglia, their functions, neurotransmitters and receptors. 2. Role of Metasympathetic, Sympathetic and Parasympathetic subdivisions, their role, functional antagonism. Role of ANS in stress and adaptation 3. Central regulation of visceral functions 4. The autonomic (visceral) reflexes, their role in assessment of vegetative tonus
  3. 3. Functional role of ANS is regulation of the visceral organs activity: respiration, cardio-vascular activity, digestion, excretion and metabolism, grow and development of the tissues and reproduction etc.
  4. 4. Autonomic Nervous System is divided into divisions: sympathetic parasympathetic metasympathetic (the enteric nervous system)
  5. 5. Metasympathetic system
  6. 6. Conductive system of the heart
  7. 7. Autonomic Nervous System The sympathetic and parasympathetic divisions provide the central visceral regulation Metasympathetic division realizes the visceral regulation on the local level.
  8. 8. Peculiarities of autonomous regulation Involuntary (from limbic system, hypothalamus, brain stem, spinal cord and limited control from cerebral cortex) Sensory input mainly from interoreceptors Efferent chain: 1-st eff.n. in CNS, 2-d n. - in ganglia Effectors – smooth muscles, cardiac muscle, glands
  9. 9. The visceral reflex arc has the receptor in the visceral organ, the afferent neuron – in the spinal ganglia, the contact (central or inter-) neuron – in the lateral horns and the efferent neuron - in the peripheral nerve centres (ganglia) which are located out of the CNS.
  10. 10. Central chain Sympathetic system: in the intermediolateral grey horns of the spinal cord P.s.- in the brain stem (medulla oblongata and midbrain) and sacral segments of s.c.
  11. 11. Sympathetic nerves The axons of the sympathetic preganlionic neurons leave the spinal cord with the ventral roots of Th1-L3-L4 spinal nerves. They pass via the white rami communicantes to the paravertebral sympathetic ganglion chain, where most of them end on the cell bodies of the postganglionic neurons
  12. 12. The post ganglionic sympathetic nerves to the head originate in the superior, middle and stelate ganglia in the cranial extension of the sympathetic ganglion chain and travel to the effectors with the blood vessels.
  13. 13. Parasympathetic nerves The cranial outflow of the parasympathetic division supplies the visceral structures in the head via oculomotor, facial, and glossopharingeal nerves, and those in the thorax and upper abdomen via the vagus nerves. The sacral outflow supplies the pelvic viscera via the pelvic branches of the second to fourth sacral spinal nerves. The preganglionic fibers in both outflows end on postganglionic neurons located on or near the visceral structures.
  14. 14. Accordingly the fiber before the efferent neuron is called preganglionic (axons are mostly myelinated, slow- conducting B fibers), and after neuron - postganglionic fibers (mostly unmyelinated C fibers)
  15. 15. 2.Ganglia with eff.neurons are located: In pre- and paravertebral ganglia in the sympathetic division of ANS In intramural ganglia (into or near the visceral organs in the parasympathetic division of ANS) The last creates metasympathetic system, if receive a sensory information directly from receptors (not from centers on brain or spinal cord)
  16. 16. Paravertebral ganglia
  17. 17. Prevertebral ganglia
  18. 18. Prevertebral ganglia
  19. 19. Ganglia of the autonomic nervous system
  20. 20. What kind structures are innervated by pre- and postganglionic fibers? Each preganglionic axon diverges to an average of 8- 9 ganglionic neurons. The axons of the ganglionic neurons end on the visceral effectors.
  21. 21. Ganglia Possess by all features of the nervous centers
  22. 22. 3,4.ANS neurotransmitters and receptors ACH – M- and H- cholinoreceptors NA – alpha-(vasoconstriction) and beta- (vasodilation) adrenergic receptors ATP, neuropeptids, dopamin Serotonin – in metasympathetic division
  23. 23. Neurontansmitters
  24. 24. Cholinoreceptors
  25. 25. Blokers Nicotine stimulates postganglionic neurons BUT there are canglionic bloking drugs^ tetraethyl ammonium ion, hexamethonium ion, pentolinium
  26. 26. 5.Sympatethic n.s., its role
  27. 27. Peculiarities of autonomous regulation Double innervation of organs Functional antagonism is determined by different neurotransmitters
  28. 28. Mechanism of antagonistic effect
  29. 29. Physiological role of s.n.s.(functions) Ergotropic : activation metabolic processes (catabolic action), releasing the energy to active actions of all systems, excepting the digestive system
  30. 30. Main physiological effects Stimulation of metabolic reactions (catabolic action – decomposition of organic substances and releasing of energy); Stimulation of heart activity and increasing of blood pressure – better nutrition of muscles Stimulation of the respiratory system (increasing of rate and depth of respiration and dilation of conductive portion of respiratory system
  31. 31. Inhibition of digestive system Dilation pupil (to see better a danger) etc
  32. 32. 6.Physiological role (functions) of p.s.s. Throphotropic: stimulation of the synthesis, accumulation and store of an energy, inhibits of activity of all systems, but activates the digestive system “Night is kingdom of vagus”
  33. 33. Methasympathetic n.s. Provides the organ and tissue levels of visceral regulation- autoregulation
  34. 34. Metasympatethic system of heart
  35. 35. 8. Interaction (antagonism, synergism) of ANS divisions Provides the different stages of an adaptive reactions to external influences
  36. 36. Adaptation Aggregate of physiological reactions which provide existence of organism and its homeostasis in response on action of external environment factors
  37. 37. Stress Response on action of strong factor Classic model of stress: the «predator- sacrifice»)
  38. 38. Physiological mechanisms of adaptation (non-specific adaptive syndrom) Stress – response reaction of organism on strong factor (stimuli) action H.Celye
  39. 39. 3 stages of stress-reaction Alarm-reaction Stage of resistance Stage of emaciation Independently of stimuli type all stages develop own to inborn mechanisms of reaction.
  40. 40. Physiological providing 1 – activation of sympathetic autonomic system (catechol-amins)
  41. 41. Intensive muscle work (to run away or struggle for survive) Needs activation of all listed above systems in order to provide mussels
  42. 42. After stress situation Recover an energy expenditure by PNS
  43. 43. 9.Central regulation
  44. 44. Brain stem Respiratory centre Hemodynamic centre Centres of digestive system: salivation, mastication (chewing,) swallowing (deglutation)
  45. 45. Hypotalamus The major control and integrative center Highest vegetative center Homeostatic center (temperature, osmotic pressure etc.) As part of limbic system - Emotions etc.
  46. 46. Cortex Archi- and paleocortex belong to limbic system – emotional component of visceral reactions Neocortex - control of the visceral functions
  47. 47. 10. Autonomic reflexes Dermato-visceral Viscero-dermal Viscero-visceral (cardiovascular autonomic reflexes, gastrointestinal autonomic reflexes)
  48. 48. Vegetative tests Ortostatic test Danini-Ashner’s test Heart rate in response on: - change of position - Pressure on eyes
  49. 49. Vegetative “tone” Basal rate of activity of s.n.s.– sympathetic tone Of p.s.s. – parasympathetic tone
  50. 50. Vegetative balance Prevalence of sympathetic tone – simpatotonia (sympathotonic persons - predisposition to cardiovascular diseases) Prevalence of parasympathetic tone – vagotonia (predisposition to diseases of digestive system) In norm – vegetative balance
  51. 51. Role of ANS in stress and adaptation
  52. 52. Adaptation Aggregate of physiological reactions which provide existence of organism and its homeostasis in response on action of external environment factors
  53. 53. Physiological mechanisms of adaptation (non-specific adaptive syndrom) Stress – response reaction of organism on strong factor (stimuli) action H.Celye
  54. 54. 3 stages of stress-reaction Alarm-reaction Stage of resistance Stage of emaciation Independently of stimuli type all stages develop own to inborn mechanisms of reaction.
  55. 55. Physiological providing 1 – activation of sympathetic autonomic system (catechol-amins) 2- Activation of HHAS (corticosteroids) – stable adaptation, resistance of immunity and organism as a whole 3- emaciation of adrenal glands – emaciation of organism
  56. 56. Alarm-reaction Mobilization of all organism resources (classic model: the «predator-sacrifice»): Stimulation of all systems (except digestive), release of energy for active muscle work. Frequently is accompanied by negative emotions, increase of nervous excitability, needs very high energy expenditures
  57. 57. Stage of resistance Mobilization of the energy resources Heightened synthesis of structural and fermentative proteins Моbilization of immune system
  58. 58. 3-th stage Emaciation and downfall (death), if factor is extremal (non-adequate) and the functional reserves are not enough Long-term adaptation– if the functional reserves enough to adapt (factor is adequate). At this stage specific mechanisms of adaptation are formed (“structural track”)
  59. 59. Eustress (good) and distress (bad) H.Selye: “If you have not a stress it means that you is died”
  60. 60. Thank you for your attention!

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