Skeletal Muscle Physiology In Rana Pipiens - PowerPoint by Rgd9zu

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									BIOLOGY 305 LABORATORY
    ANNOUNCEMENTS

   No Labs Next Week Except Monday Section!
ANNOUNCEMENTS
   Biology 305L Midterm:
       • Friday, March 13th

       • Begins at noon but may not leave before 1:00 pm

       • In LH 7

       • Bring pencil/pen + erasure

       • Bring student ID

       • No calculators, cell phones, iPods etc…
ANNOUNCEMENTS
   Biology 305L Midterm:

    – Old midterm will be posted!

    – Use old exam to test what you know

          – Do NOT memorize answers!
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 (e.g. G. muscle exercise)
    –   Traces produced using LabScribe (be able to draw)
    –   Any/all graphs made in lab (i.e. Excel graphs)
    – Notes from lab lead off lecture
ANNOUNCEMENTS
   No Lab Lecture:

    – Next Friday (March 13th) due to Midterm


    – Read & print out Exercise 6 before coming to lab (after
      spring break)
ANNOUNCEMENTS
   Presentations & Posters:

    – Information will be passed out in lab after break

    – Both poster and oral presentation will be based on
      data gathered in lab
REVIEW OF THIS WEEK: SKELETAL
MUSCLE PHYSIOLOGY
“Us” versus Them:
 Vertebrate Skeletal Muscle:
REVIEW OF THIS WEEK: SKELETAL
MUSCLE PHYSIOLOGY
“Us” Versus Them:
   Invertebrates (Arthropods):
REVIEW OF THIS WEEK:
SKELETAL MUSCLE PHYSIOLOGY
      Gastrocnemius Muscle:
         Innervated by motor neurons in Sciatic Nerve
         Contractile force measured with Transducer

         Increases in response amplitude achieved by:
               • Motor unit recruitment



              • Additive effect
          SKELETAL
      MUSCLE PHYSIOLOGY
Force of Contraction:
   Stimulus Amplitude:

    – Stimulating nerve with increasing stimulus
      amplitude results in increased contractile force
              » Due to recruitment of additional motor units
      SKELETAL
        MUSCLE
    PHYSIOLOGY
Force of Contraction:
   Stimulus Frequency:

    – As stimulus frequency increases,
      response amplitude increases

       Single twitches 
          Summed twitches 
                        Tetanus
SKELETAL MUSCLE PHYSIOLOGY
Force of Contraction:
   Summation:
    – Partially sustained contraction

    – Result of continuous APs
      from CNS
SKELETAL MUSCLE PHYSIOLOGY
Summation:
   Summation of single
    twitches  more forceful
    contraction
         SKELETAL
           MUSCLE
       PHYSIOLOGY
Tetanus:
   State of maximum contraction

   Reached when:
       • APs stimulate muscle repeatedly at high freq.
    SKELETAL
      MUSCLE
  PHYSIOLOGY
Tetanus:

• Maximum force (tension) produced by muscle at a
  particular stimulus frequency and intensity:
      SKELETAL
        MUSCLE
    PHYSIOLOGY
Fatigue:
   Muscle cannot generate/sustain expected output
        • Even as supra threshold stimuli are applied


   Occurs in presence of prolonged, high freq. stimuli

   Occurs more readily in certain fiber types
MUSCLE FIBER TYPES

   Slow-Twitch and
    Fast-Twitch Muscle
    Cells Differ in Contraction
    Speed, Strength and
    Fatigue Resistance
               MUSCLE FIBER TYPES
   Three basic types of muscle cells:
    – Slow twitch (slow oxidative; aerobic)
   MUSCLE FIBER TYPES
Three basic types of muscle cells:
   – Fast twitch (fast glycolytic; anaerobic)
       MUSCLE FIBER
             TYPES
Three basic types of muscle cells:

   – “Intermediate” fibers:

								
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