Introduction to the PNS
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The document outlines the anatomy and physiology of the peripheral nervous system, detailing the somatic and autonomic systems, including specific cranial nerves and their functions. It compares sympathetic and parasympathetic systems in terms of organization, function, and neurotransmitters. Furthermore, it addresses the implications of the autonomic nervous system on health and outlines major causes of death.
Introduction to the PNS
- 1. Peripheral Nervous System Brian J. Piper, Ph.D., M.S.
- 2. The Nervous System -------------------------------Enteric (digestive)
- 3. Goals • Anatomy & Physiology of: – Somatic Nervous System – Autonomic Nervous System
- 4. Meninges of the Spinal Cord Spinal cord Ventral root Subarachnoid Pia mater space Dorsal root Spinal nerve Arachnoid mater Epidural space Dorsal root Dura mater ganglion Dorsal root Dorsal branch Spinal (dorsal ramus) nerve Ventral branch Dorsal root (ventral ramus) ganglion Spinal cord Ventral root Epidural space Thoracic vertebra Body of vertebra (a) (b) 4
- 5. Refresher I • Afferent: towards center (brain), ≈sensory • Efferent: away from center (brain), ≈motor • Ganglia: mass of cell bodies • Plexus: network of neurons
- 6. Refresher II • Nicotinic: subtype of Acetycholine receptor Jean Nicot Nicotiana tobaccum 1530-1600 • Muscarinic: subtype of Acetycholine receptor Amanita muscaria
- 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. 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 Heavenly http://en.wikipedia.org/wiki/List_of_mnemonics_for_the_cranial_nerves
- 9. CN I: Olfactory • Connect nasal cavity to temporal cortex • Substantial individual differences • Forms new neurons throughout life!
- 10. CN II: Optic • Connects retina to thalamus (lateral geniculate nucleus) • Partial decussation
- 11. CN VIII: Vestibulocochlear (Auditory) • Connects cochlea to brainstem • Responsible for balance & hearing
- 12. Somatic Nervous System • Voluntary Nervous System – Motor cell bodies in ventral horn – Send axons to muscle – Use Acetylcholine to stimulate
- 13. Autonomic NS: Two Neurons ACh ACh: Acetylcholine Howland & Mycek (2006). Lippincott’s Illustrated Reviews: Pharmacology. p. 36.
- 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”
- 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 - Salivation Low & Engstrom (2012). Disorders of the ANS. In Harrison’s VII, Ch 375, p. 3352.
- 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 - Salivation Low & Engstrom (2012). Disorders of the ANS. In Harrison’s VII, Ch 375, p. 3352.
- 18. Sympathetic & Parasympathetic Innervation I • Central components “accident” example • All at once (Sym) versus individual components (PS)
- 19. Sympathetic versus Parasympathetic Preganlionic projection: short long
- 20. Comparison Sympathetic Parasympathetic Origin T1 to T12, L1, L2 CN III, VII, IX, X, S2, S3 Target organs Diffuse Localized Transmitter Adrenergic Muscarinic Amplification Yes (1:20) No (1:1)
- 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. Light Reading O:15 to 3:58: http://www.youtube.com/watch?v=sPS7GnromGo
- 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