Central Nervous System, The Autonomic Nervous System


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Central Nervous System, The Autonomic Nervous System

  1. 1. Central Nervous SystemThe Autonomic Nervous System
  2. 2. Nervous System• coordinates the actions of the body• transmits signals between different parts of the body
  3. 3. Sensory input – gathering information monitor changes occurring inside and outside the body stimuliIntegration – process and interpret sensory input +/- actionMotor output = response to integrated stimuli activates muscles/ glands
  4. 4. Nervous System Central Nervous System Periferic Nervous System SENSORY MOTOR AUTONOMIC SOMATIC Sympathetic NERVOUS NERVOUS SYSTEM SYSTEMParasympathetic Enteric Nervous System
  5. 5. Autonomic Nervous Systeminvoluntary – automatic – visceral/glands motor system SENSORY MOTOR AUTONOMIC Sympathetic NERVOUS SYSTEM Parasympathetic Enteric Nervous System
  6. 6. Somatic vs. Autonomic Effectors (Targets) skeletal muscle smooth/cardiac muscle & glands Efferent pathways1 neuron - myelinated axon 2 neuron pathway –from ventral horn of spinal 1st- preganglionic and bodycord all the way to effector resides in brainstem/S2-S4 cord – myelinated axon; 2nd- postganglionic and body resides in autonomic ganglion – unmyelinated axon SNS = short pre/long post ganglionic axon PsNS = long pre/short post ganglionic axon
  7. 7. Somatic vs. Autonomic
  8. 8. Neurotransmitters somatic vs. autonomic Allpreganglionic fibers release AchAll motor neurons release Ach postganglionic PsNS fibers release Ach- always stimulatory postganglionic SNS fibers release Norepinephrine → stimulatory or inhibitory (based on receptor types)
  9. 9. http://health-7.com/Lippincotts%20Illustrated%20Reviews%20Pharmacology/3.%20The%20Autonomic%20Nervous%20System/8
  10. 10. Divisions of the ANSSympathetic NS • dual innervation- usually stimulatory • opposing effects=>energy consum • may work independently • may work together - eachParasymathetic NS one controlling one stage of- usually inhibitory the process =>conservation of energy
  11. 11. Sympathetic nervous systemThe “fight-or-flight” system: involves activities like: other activities are reduced exercise, excitement, (GI/urinary) emergency and embarrassment ↑ flow to muscle =>↓ blood flow to the organs heart rate ↑ - breathing ↑rapid and deep bronchioles dilate - ↑ventilation => delivering more oxygen to cells the skin is cold and sweaty the pupils dilate liver releases more glucose into circulation lipolysis to the level of the adipocytes
  12. 12. Sympathetic nervous system• Cervical-thoraco- lumbar division• Short preggl/long postggl
  13. 13. Adrenal medulla• same embryological origin as the sympathetic ganglia• fibers from the thoracic splanchnic nerves pass thru the Celiac Ganglion↓ terminate in the medullary adrenal gland=> secrete epi- and norepinephrine into the Barwick et al. - Embryology of the adrenal glands and its relevance to diagnostic imaging, Clin Rad, 2005, Vol. 60, Issue 9, pag: 953-959 blood
  14. 14. Parasympathetic nervous system• active in non-stressful situations – keep the body energy => involves activities like: salivation, lacrimation, digestion, defecation,urination• Activats lens accommodation - close vision -↑ gastrointestinal tract activity -↓ heart rate, blood pressure -↓ respiratory rates - constricted pupils - warm skin
  15. 15. Parasympathetic nervous system• Fibers emerge from CR.NN. - III,VII,IX, X S2-S4 spinal cord• Long preganglionic fibers synapse in terminal or intramural ganglia
  16. 16. Enteric Nervous System•acomplex, independentnervous systemlines the gastrointestinal tract“second brain”“the brain of the gut” ► motility controls essential functions► secretion ► blood flow
  17. 17. ENSFurness JB (2006) The Enteric Nervous System. Blackwell, Oxford, pp 274
  18. 18. Connections CNS - ENSANS: Sympathetic & Parasympathetic
  19. 19. The neural connections between theENS and CNS, and neuralconnections betweengastrointestinal organsThe digestive system contains full reflex circuits of theENS (motor neurons and interneurons in blue, sensoryneurons in purple). Pathways from the gastrointestinaltract project outwards, via intestinofugal neurons(red), to the CNS (neurons in yellow), sympatheticganglia, gallbladder and pancreas. Neurons insympathetic prevertebral ganglia (green) receive bothCNS and ENS inputs. Sensory information goes bothto the ENS, via intrinsic primary afferent (sensory)neurons (purple) and to the CNS via extrinsic primaryafferent neurons (also purple) that follow spinal andvagal afferent routes. Pathways from the CNS reachthe ENS and gastrointestinal effector tissues throughvagal, sympathetic and pelvic pathways.Abbreviations: CNS, central nervous system;ENS, enteric nervous system. Furness, JB – The enteric nervous system and neurogastroenterology, Nat Rev Gastroenterol. Hepatol, doi: 10.1038/nrgastro. 2012.32
  20. 20. Visceral afferents and referred pain Maps of Referred Pain Grant’s Atlas 12 2009
  21. 21. Referred pain• visceral pain afferents travel the same path as somatic pain afferents• sometimes - pain stimuli from viscera is interpreted as somatic pain origin by the brain Eg - heart attack (T1-T5 supply chest & medial aspect of left arm)
  22. 22. CNS processing and modulation of visceral sensationPain sensation →sensory discriminatorycomponentsPain affect →combination ofemotional andcognitive appraisalsrelated to the painexperience PAG, periaqueductal gray; PB, parabrachial nucleus of the dorsolateral pons; AMYG, amygdala; HT, hypothalamus; Vmpo, MDvc & VPL, thalamic nuclei (ventromedial part of the posterior nuclear complex, ventrocaudal part of the medial dorsal nucleus and ventroposterior lateral nucleus respectively); ACC, anterior cingulate cortex; PCC, posterior cingulate cortex; PF, prefrontal cortex; SMA, supplementary motor area; S1 & S2, primary & secondary somatosensory cortices; M1, primary motor cortex; PPC, posterior parietal complex. Van Oudenhove L, Demittenaere K., Tack J, Aziz Q – Central nervous system involvement in functional gastrointestinal disorders, 2004, Best Pract & Research Cl Gastroentero, Vol 18, pag 663-680
  23. 23. Levels of ANS Control• hypothalamus = the main integration center of ANS activity• subconscious cerebral input - via limbic system - influences hypothalamic function• other controls come from: - the cerebral cortex - the reticular formation - the spinal cord
  24. 24. Hypothalamic Control• centers of the hypothalamus control: – heart activity and blood pressure – body temperature – water balance – endocrine activity http://www.upright-health.com/pituitary-gland.html – emotional stages (rage, pleasure) – biological drives (hunger, thirst, sex) – reactions to fear and the “fight-or-flight” system.
  25. 25. Superior nervous structures involvein control of ANS: PAG
  26. 26. Superior nervous structures involvein control of ANS: Amygdala Hamann S – Affective neuroscience – Amygadala’s role in Experiencing Fear, 2011, Current Biol, Vol 21, R75-R77
  27. 27. EMS (Emotional Motor System) – amygdala - hypothalamus - periaquaductal greyIntegrates: - autonomic - neuroendocrine - pain modulatory responses EMS = neurobiological basis of stress sensitivity http://brainmind.com/BrainLecture5.html