SKELETAL MUSCLE PHYSIOLOGY IN Rana pipiens

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THE FROG SCIATIC NERVE

• BIOLOGY 305 LABORATORY

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ANNOUNCEMENTS

• Lab Quiz
• Next week in lab
• Based on
• Crayfish Demo
• Sciatic Nerve Exercises

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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)

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REVIEW OF LAST WEEK MUSCLE RECEPTOR ORGAN OF
CRAYFISH

• MRO1
• MRO2s
• Sensory Adaptation

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THE ACTION POTENTIAL

• Resting Membrane Potential
• Threshold
• Depolarization
• Repolarization

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THE SCIATIC NERVE

• Leopard Frog
• Sciatic Nerve
• Composed of

www.zoo.utoronto.ca/natalie/ frogpage.html
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THE SCIATIC NERVE

• Goals Include
• Determine threshold
• Measure compound APs
• Observe recruitment
• Calculate conduction velocity
• See temperature influences
• Determine directionality

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THE SCIATIC NERVE

• Each Neuron Has A Threshold
• Voltage at which a neuron is sufficiently
  stimulated
• Sub threshold stimulus ?

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THE SCIATIC NERVE

• Compound Action Potentials (CAP)
• Summation of action potentials (APs)

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THE SCIATIC NERVE

• Recruitment
• As you apply supra-threshold stimuli to a nerve
  with increasing voltage

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THE SCIATIC NERVE

• Maximum Recruitment
• At some stimulus voltage
• Further increases in stimulus intensity

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THE SCIATIC NERVE

• The Stimulus Artifact
• Deflection due to application of voltage to nerve
• If stimulus exceeds 0 Volts

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THE SCIATIC NERVE

• Conduction Velocity of APs
• In a single neuron, depends on
• In lab youll measure conduction velocity of a
  CAP

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THE SCIATIC NERVE

• Directionality
• In an excised sciatic nerve, APs should travel
• This should occur irrespective of whether
  individual neurons in nerve are

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THE SCIATIC NERVE

• The Dissection
• To minimize of animals used, each group will
  share a frog with another group

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THE SCIATIC NERVE

• The Dissection
• Excision of Distal End

www.engin.brown.edu/.../MuscleExp/ Dissection.htm
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THE SCIATIC NERVE

• The Dissection
• Excision of Proximal
• End

www.engin.brown.edu/.../MuscleExp/ Dissection.htm
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THE SCIATIC NERVE

• Instrumentation Set Up
• The Nerve Bath Chamber
• Keep track of which end is which
• proximal versus distal
• To retain blood supply, tie off proximal end
  (spine) last
• Cut LONGEST section possible
• Be gentle. Do NOT stretch nerve!
• Keep nerve wet with Ringers solution

www.biopac.com/newsletter/ september/frog_nerve.ht

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THE SCIATIC NERVE

• Instrumentation Set Up
• Electrodes
• Stimulate and Record
• Response(s) from Nerve

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THE SCIATIC NERVE

• Instrumentation Set Up
• Electrodes
• Stimulating Electrode ( -)
• Connect to one end of nerve bath
• Recording Electrode ( -)
• Connect to other end
• Ground
• Placed in- between

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Recording Electrodes
Nerve Bath Chamber
Stimulating Electrodes
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THE SCIATIC NERVE

• Instrumentation Set Up
• Electrodes
• Place leads on opposite sides of bath
• Space apart by one pin
• No two electrodes should touch!

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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 Ringers from nerve bath while
  running experiments

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THE SCIATIC NERVE

• Instrumentation Set Up
• iWORX Unit
• Stimulator
• Digitizer
• Amplifier
• Recorder

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