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THE FROG SCIATIC NERVE

THE FROG SCIATIC NERVE. BIOLOGY 305 LABORATORY. ANNOUNCEMENTS. Lab Quiz: Next week in lab Based on: Crayfish Demo Sciatic Nerve Exercises. REVIEW OF LAST WEEK: MUSCLE RECEPTOR ORGAN OF CRAYFISH. Flow of Information: MRO Nerve Suction Electrode Junction box (amplifier)

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THE FROG SCIATIC NERVE

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  1. THE FROG SCIATIC NERVE BIOLOGY 305 LABORATORY

  2. ANNOUNCEMENTS • Lab Quiz: • Next week in lab • Based on: • Crayfish Demo • Sciatic Nerve Exercises

  3. REVIEW OF LAST WEEK: MUSCLE RECEPTOR ORGAN OF CRAYFISH Flow of Information: • MRO Nerve • Suction Electrode • Junction box (amplifier) • Audio amplifier • Iworx box • Computer (LabScribe)

  4. REVIEW OF LAST WEEK: MUSCLE RECEPTOR ORGAN OF CRAYFISH • MRO1: • MRO2s: • Sensory Adaptation:

  5. THE SCIATIC NERVE • Leopard Frog: • Sciatic Nerve: • Composed of Mixed Axons: www.zoo.utoronto.ca/natalie/ frogpage.html

  6. THE SCIATIC NERVE • Goals Include: • Determine threshold • Measure compound APs • Observe recruitment • Calculate conduction velocity • See temperature influences • Determine directionality

  7. THE SCIATIC NERVE • Each Neuron Has A Threshold: • Voltage at which a neuron is sufficiently stimulated to fire an Action Potential (AP) • Sub threshold stimulus 

  8. THE SCIATIC NERVE • Compound Action Potentials (CAP): • Summation of action potentials (APs)

  9. THE SCIATIC NERVE • Recruitment: • As you apply supra-threshold stimuli to a nerve with increasing voltage

  10. THE SCIATIC NERVE • Maximum Recruitment: • At some stimulus voltage

  11. THE SCIATIC NERVE • The Stimulus Artifact: • Deflection due to application of voltage to nerve • If stimulus exceeds 0 Volts, you should see a stimulus artifact on trace

  12. THE SCIATIC NERVE • Conduction Velocity of APs: • In a single neuron, depends on • In lab you’ll measure conduction velocity of a CAP at room temperature and under cold conditions

  13. THE SCIATIC NERVE • Directionality: • In an excised sciatic nerve, CAPs should travel

  14. THE SCIATIC NERVE The Dissection: • To minimize # of animals used, each group will share a frog with another group

  15. THE SCIATIC NERVE The Dissection: • Excision of Distal End www.engin.brown.edu/.../MuscleExp/ Dissection.htm

  16. THE SCIATIC NERVE The Dissection: • Excision of Proximal End www.engin.brown.edu/.../MuscleExp/ Dissection.htm

  17. THE SCIATIC NERVE Instrumentation & Set Up: • The Nerve Bath Chamber: www.biopac.com/newsletter/ september/frog_nerve.ht

  18. THE SCIATIC NERVE Instrumentation & Set Up: • Electrodes:

  19. Recording Electrodes Nerve Bath Chamber Stimulating Electrodes

  20. THE SCIATIC NERVE Instrumentation & Set Up: • Electrodes • Place + & – leads on opposite sides of bath • Space apart by one pin • No two electrodes should be attached to same pin!

  21. THE SCIATIC NERVE Instrumentation & Set Up • Electrode Tips: • Confirm everything is plugged in • Confirm good electrical contact • Only connect electrodes to pins in contact with nerve! • Remove excess Ringer’s from nerve & pins in bath while running experiments

  22. THE SCIATIC NERVE Instrumentation & Set Up: • iWORX Unit

  23. THE SCIATIC NERVE iWorx Stimulator Panel (OUTPUT) iWorx Recording Channels (INPUT)

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