Introduction to the PNS

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This presentation was delivered to 1st year pharmacy students and accompanies and accompanies Goodman & Gilman's (12e) chapter 8.

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Introduction to the PNS

  1. 1. Peripheral Nervous System Brian J. Piper, Ph.D., M.S.
  2. 2. The Nervous System -------------------------------Enteric (digestive)
  3. 3. Goals• Anatomy & Physiology of: – Somatic Nervous System – Autonomic Nervous System
  4. 4. Meninges of the Spinal CordSpinal cordVentral root Subarachnoid Pia mater spaceDorsal rootSpinal nerve Arachnoid mater Epidural spaceDorsal root Dura materganglion Dorsal root Dorsal branch Spinal (dorsal ramus) nerve Ventral branch Dorsal root (ventral ramus) ganglion Spinal cord Ventral root Epidural spaceThoracicvertebra Body of vertebra(a) (b) 4
  5. 5. Refresher I• Afferent: towards center (brain), ≈sensory• Efferent: away from center (brain), ≈motor• Ganglia: mass of cell bodies• Plexus: network of neurons
  6. 6. Refresher II• Nicotinic: subtype of Acetycholine receptor Jean Nicot Nicotiana tobaccum 1530-1600• Muscarinic: subtype of Acetycholine receptor Amanita muscaria
  7. 7. Peripheral Nervous System• Cranial nerves arising from the brain • Somatic fibers connecting to the skin and skeletal muscles • Autonomic fibers connecting to viscera• Spinal nerves arising from the spinal cord • Somatic fibers connecting to the skin and skeletal muscles • Autonomic fibers connecting to viscera 7
  8. 8. 12 Cranial Nerves • On Old Olympic Towering Tops A Finn And German Viewed Some Hops • Once One Openly Told Tourists About Fighting Vampires Gobling Various Antelope Herds • Oh Once One Takes The Anatomy Final Very Good Vacations Are Heavenlyhttp://en.wikipedia.org/wiki/List_of_mnemonics_for_the_cranial_nerves
  9. 9. CN I: Olfactory• Connect nasal cavity to temporal cortex• Substantial individual differences• Forms new neurons throughout life!
  10. 10. CN II: Optic• Connects retina to thalamus (lateral geniculate nucleus)• Partial decussation
  11. 11. CN VIII: Vestibulocochlear (Auditory)• Connects cochlea to brainstem• Responsible for balance & hearing
  12. 12. Somatic Nervous System• Voluntary Nervous System – Motor cell bodies in ventral horn – Send axons to muscle – Use Acetylcholine to stimulate
  13. 13. Autonomic NS: Two Neurons ACh ACh: AcetylcholineHowland & Mycek (2006). Lippincott’s Illustrated Reviews: Pharmacology. p. 36.
  14. 14. Autonomic Nervous System• Autonomous “automatic”• Functions: blood pressure, heart rate, sleep, bladder & bowel function• Sympathetic NS: “fight or flight” Medulla: Epinephrine Cortex: Cortisol Walter Cannon• Parasympathetic NS: “rest & maintain”
  15. 15. Automobile Analogy
  16. 16. Functional Consequences of Normal ANS Function Sympathetic Parasympathetic Heart Rate Increased Decreased Blood pressure Increased Decreased Bowel motility Decreased Increased Lung Bronchodilation Bronchoconstriction Pupils Dilation Constriction Adrenal glands Catecholamine release - Sexual function (males) Orgasm Erection Bladder Increased sphincter tone Decreased sphincter tone Parotid gland - SalivationLow & Engstrom (2012). Disorders of the ANS. In Harrison’s VII, Ch 375, p. 3352.
  17. 17. Unbalanced Sympathetic Parasympathetic Heart Rate Increased < Decreased Blood pressure decreased (mildly) Increased > Bowel motility Decreased Increased Lung Bronchodilation Bronchoconstriction Pupils Dilation Constriction Adrenal glands Catecholamine release - Sexual function (males) Orgasm Erection Bladder Increased sphincter tone < Decreased sphincter tone Parotid gland - SalivationLow & Engstrom (2012). Disorders of the ANS. In Harrison’s VII, Ch 375, p. 3352.
  18. 18. Sympathetic & Parasympathetic Innervation I• Central components “accident” example• All at once (Sym) versus individual components (PS)
  19. 19. Sympathetic versus ParasympatheticPreganlionic projection: short long
  20. 20. Comparison Sympathetic ParasympatheticOrigin T1 to T12, L1, L2 CN III, VII, IX, X, S2, S3Target organs Diffuse LocalizedTransmitter Adrenergic MuscarinicAmplification Yes (1:20) No (1:1)
  21. 21. Comparison of Somatic and Autonomic Nervous Systems Somatic Sympathetic ParaSymp # neurons 1 >1 2 Myelinated Yes Pre-Gang Pre-Gang Neuro- ACh Pre: ACh Pre: ACh transmitter Post: NE, Ep Post: ACh Receptor Nicotinic Pre: Nic Pre: Nic Post: Adren Post: mus
  22. 22. Light ReadingO:15 to 3:58: http://www.youtube.com/watch?v=sPS7GnromGo
  23. 23. ANS (Stress) & Health• Top Causes of Death (2009): – 1) Heart Disease – 2) Cancer – 3) Chronic respiratory diseases – 4) Stroke – 5) Accidents – 6) Alzheimer’s – 7) Diabetes – 8) Influenza & pneumonia – 9) Kidney disease – 10) Suicide http://www.cdc.gov/nchs/data/nvsr/nvsr59/nvsr59_04.pdf

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