1. The Peripheral Nervous System Lecture 7

2. Peripheral N. S. n Cranial Nerves - 12 pair n Spinal Nerves - 31 pair n Somatic Division l Sensory info l Body Movement n Autonomic division - Homeostasis l regulation ~

3. Cranial Nerves n From ventral surface l numbered anterior  posterior n Sensory, motor, or mixed n Mnemonic ~

4. Oh To Touch And Feel Very Green Vegetables A H Olfactory Optic Oculomotor Trochlear Trigeminal Abducens Facial Vestibulococlear Glossopharangeal Vagus Accessory (Spinal) Hypoglossal I II III IV V VI VII VIII IX X XI XII On Old Olympus Towering Top A Famous Vocal German Viewed Some Hops

5. Spinal Nerves n 1 pair for each vertebral segment n 8 pr. cervical (C1-C8) n 12 pr. thoracic (T1-T12) n 5 pr. lumbar (L1-L5) n 5 pr. sacral (S1-S5) n 1 pr coccygeal ~

6. Spinal Nerves n Thoracic nerves relatively small back & ribs n Cervical, lumbar, & sacral: large nerves rest of the body n All Interconnect l after leaving vertebral canal l form 4 major plexuses cervical, brachial, lumbar, sacral ~

7. Somatic Nervous System n Sensory input l receptors  DRG  dorsal SC l Dorsal column-medial lemniscal pathway l Spinolthalamic tract n Motor output l Lateral SC  ventral horns  muscles l Corticospinal tract l Rubrospinal tract ~

8. Dermatomes n Sensory innervation l each spinal nerve has receptive field n Overlap at distal branches l redundancy l retain some sensation even if a complete spinal nerve destroyed ~

9. Somatic N.S.: Motor Output

10. The Lateral Pathway n Voluntary movement l distal limbs l 2 tracts n Corticospinal tract about 1 million axons n Rubrospinal tract small part of pathway ~

11. Motor N.S. n Striate muscle l uninterrupted neuron  motor neuron l nerve-dependent n Excitatory only at neuroeffector synapse l NT is acetylcholine (ACh) cholinergic l Nicotine = direct agonist (AG) l Curare = direct antagonist (ANT) ~

12. Somatic Motor N. S. Spinal Cord Motor Neuron Effector ACh

13. n Homeostasis n Effectors l Smooth Muscle l Cardiac Muscle l Glands ~ Autonomic N. S.

14. n Not nerve-dependent n Sympathetic l Emergency, flight/fight n Parasympathetic l Conservation / vegetative ~ Autonomic Subdivisions

15. Effector Ganglion Preganglionic neuron Postganglionic neuron Autonomic N. S.: General Features

16. Effector Autonomic N. S.: General Features ACh n Nicotinic l different R-subtype than neuromuscular ~

17. Effector Autonomic N. S.: General Features ACh n Neuroeffector junction l Different NT for each division ~

18. Pharmacology of Autonomic NS n Preganglionic neuron releases ACh n Different NT at effectors l sympathetic division: NE Norepinephrine (or noradrenaline) l parasympathetic division: ACh ~

19. Sympathetic vs. Parasympathetic n Sympathetic l ganglia near spinal cord l interconnected ---> active together l long-lasting effects n Parasympathetic l ganglia near effector l discrete ---> active independently l transient effects n Antagonistic regulation ~

20. Effector Responses Effector Sympathetic Parasympathetic Heart + - Respiration + - GI - + Immune system - + Sweat glands + no input Iris + (radial) + (sphincter) ~

21. Parasympathetic Post- Pre- Sympathetic Adrenal Glands ACh Glands Smooth muscle NE

22. Sympathetic Arousal Syndrome n Fight or flight situations l Diffuse sympathetic activation n Adrenal glands l releases NE into blood l maintains sympathetic arousal n Parasympathetic rebound l antagonistic regulation ~