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SKELETAL MUSCLE PHYSIOLOGY IN Rana pipiens

SKELETAL MUSCLE PHYSIOLOGY IN Rana pipiens. BIOL 305L. Midterm Exam: Friday, March 15 th during lab lecture No calculators Format: multiple choice, short ans, essay, fill in blank, T/F No labs that week! NO MAKEUP EXAM UNLESS UNIVERSITY APPROVED EMERGENCY

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SKELETAL MUSCLE PHYSIOLOGY IN Rana pipiens

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  1. SKELETAL MUSCLE PHYSIOLOGY IN Rana pipiens BIOL 305L

  2. Midterm Exam: Friday, March 15th during lab lecture No calculators Format: multiple choice, short ans, essay, fill in blank, T/F No labs that week! NO MAKEUP EXAM UNLESS UNIVERSITY APPROVED EMERGENCY Old midterm will be posted online next week. Use it to TEST what you know. Do NOT memorize answers!! ANNOUNCEMENTS

  3. ANNOUNCEMENTS • Study for Midterm: • Background concepts/theory • Experimental results (expected) • Flow of information/experimental set up (be able to draw) • Names & function of all instruments • Anatomy (name of muscles, organs, nerves and organisms) • Lab exercises (handouts), especially the introduction • Observations in lab • Traces produced using LabScribe (be able to draw) • Any/all graphs made (i.e. Excel graphs) • Notes from lab lead off lecture

  4. REVIEW: THE SCIATIC NERVE Main Points: • Mixed Nerve • Stimulus Artifact • Threshold • Compound Action Potential • Recruitment • Maximum Recruitment • Conduction Velocity • Bidirectionality • Effect of temperature

  5. THIS WEEK: SKELETAL MUSCLE PHYSIOLOGY The Dissection: • Isolation of frog: Instrumentation & Equipment:

  6. SKELETAL MUSCLE PHYSIOLOGY • The Stimulus: • iWorx Unit • Stimulating • Electrode

  7. SKELETAL MUSCLE PHYSIOLOGY The Response: • Relative force of muscle contraction measured by deflection of force transducer blade

  8. SKELETAL MUSCLE PHYSIOLOGY Motor Unit: • Unit of contraction in intact organisms • Composed of:

  9. slice from spinal chord motor neuron axons in a nerve leading from spinal chord muscle neuromuscular junction

  10. SKELETAL MUSCLE PHYSIOLOGY “Us” versus Them: • Vertebrate Skeletal Muscle: • A motor neuron innervates a muscle fiber • A muscle fiber is innervated by • AP in motor neuron is

  11. SKELETAL MUSCLE PHYSIOLOGY “Us” Versus Them: • Invertebrates (Arthropods): • A motor neuron can innervate a muscle fiber • Multiple motor neurons may innervate • motor neurons exist

  12. SKELETAL MUSCLE PHYSIOLOGY Gastrocnemius Muscle: • In intact organisms, innervated by • Sciatic nerve will be removed in lab • You will stimulate muscle DIRECTLY • Contractile force measured with

  13. SKELETAL MUSCLE PHYSIOLOGY Two Methods to Increase Contractile Force: • Increase Stimulus : • Illustrates • Increase Stimulus : • Illustrates

  14. SKELETAL MUSCLE PHYSIOLOGY Recruitment: • As stimulus intensity increases, more muscle fibers reach threshold and contract • The greater number of muscle fibers recruited, the greater

  15. SKELETAL MUSCLE PHYSIOLOGY Recruitment: • A muscle reaches MAXIMUM RECRUITMENT when

  16. SKELETAL MUSCLE PHYSIOLOGY Temporal Summation: • In lab, we’ll also observe the relationship between stimulus frequency and force of contraction

  17. SKELETAL MUSCLE PHYSIOLOGY Single twitch Single Twitch • Single contraction • If multiple twitches occur

  18. SKELETAL MUSCLE PHYSIOLOGY Summation: • Sustained contraction due to • Muscle only • Results in

  19. SKELETAL MUSCLE PHYSIOLOGY Tetanus: • State of • Muscle does • Results in contraction of

  20. SKELETAL MUSCLE PHYSIOLOGY Fatigue: • Some types of muscle fibers

  21. MUSCLE FIBER TYPES • Different Muscle Cell Types Differ in Susceptibility to Fatigue (as well as threshold, contractile strength, etc..) • Slow versus Fast Twitch Muscle Fibers

  22. MUSCLE FIBER TYPES Slow twitch (oxidative; aerobic)

  23. MUSCLE FIBER TYPES Fast twitch (glycolytic; anaerobic)

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