THE FROG SCIATIC NERVEANNOUNCEMENTSREVIEW OF LAST WEEK: MUSCLE RECEPTOR ORGAN OF CRAYFISHREVIEW OF LAST WEEK: MUSCLE RECEPTOR ORGAN OF CRAYFISHTHE SCIATIC NERVESlide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19THE SCIATIC NERVESlide 21Slide 22Slide 23THE FROG SCIATIC NERVEBIOLOGY 305 LABORATORYANNOUNCEMENTSLab Quiz: •Next week in lab•Based on:–Crayfish Demo–Sciatic Nerve ExercisesREVIEW OF LAST WEEK: MUSCLE RECEPTOR ORGAN OF CRAYFISHFlow of Information:MRO NerveSuction Electrode Junction box (amplifier)Audio amplifierIworx boxComputer (LabScribe)REVIEW OF LAST WEEK: MUSCLE RECEPTOR ORGAN OF CRAYFISHMRO1:MRO2s:Sensory Adaptation:THE SCIATIC NERVELeopard Frog:Sciatic Nerve:–Composed of Mixed Axons:www.zoo.utoronto.ca/natalie/ frogpage.htmlTHE SCIATIC NERVEGoals Include:•Determine threshold •Measure compound APs•Observe recruitment •Calculate conduction velocity•See temperature influences•Determine directionalityTHE SCIATIC NERVEEach Neuron Has A Threshold:–Voltage at which a neuron is sufficiently stimulated to fire an Action Potential (AP)–Sub threshold stimulus THE SCIATIC NERVECompound Action Potentials (CAP):–Summation of action potentials (APs)THE SCIATIC NERVERecruitment:–As you apply supra-threshold stimuli to a nerve with increasing voltageTHE SCIATIC NERVEMaximum Recruitment:–At some stimulus voltageTHE 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 traceTHE 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 conditionsTHE SCIATIC NERVEDirectionality:–In an excised sciatic nerve, CAPs should travelTHE SCIATIC NERVEThe Dissection:To minimize # of animals used, each group will share a frog with another groupTHE SCIATIC NERVEThe Dissection:Excision of Distal Endwww.engin.brown.edu/.../MuscleExp/ Dissection.htmTHE SCIATIC NERVEThe Dissection:Excision of Proximal Endwww.engin.brown.edu/.../MuscleExp/ Dissection.htmTHE SCIATIC NERVEInstrumentation & Set Up: The Nerve Bath Chamber:www.biopac.com/newsletter/ september/frog_nerve.htTHE SCIATIC NERVEInstrumentation & Set Up:Electrodes:SciaticNerveSetUp2.jpgStimulatingElectrodesRecording ElectrodesNerveBathChamberTHE SCIATIC NERVEInstrumentation & Set Up:Electrodes–Place + & – leads on opposite sides of bath»Space apart by one pin »No two electrodes should be attached to same pin!THE SCIATIC NERVEInstrumentation & 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 experimentsTHE SCIATIC NERVEInstrumentation & Set Up:iWORX UnitTHE SCIATIC NERVEiWorxStimulator Panel(OUTPUT)iWorx Recording