BMS100 Plus Hour Assignment - Skeletal Muscle Physiology on PhysioEx
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  1. Go to the Biology Computer Lab, EBS 215.
  2. Start the PhysioEx software and make the following selections: Main Menu > Skeletal Muscle Physiology
  3. Go to the Experiment menu and select Single Stimulus.
    1. Set "Muscle Length" to 75 millimeters (mm.).
    2. Set the "Voltage (V)" to 1.0 V.
    3. Stimulate the muscle with 1.0 V by pressing the "Stimulate" button. Click "Record Data."
    4. Set the voltage to 2.0 V, stimulate the muscle again, and click "Record Data."
      Questions
      1. How much force was generated when the muscle was stimulated with 1.0 V?
      2. How much force was generated when the muscle was stimulated with 2.0 V?
      Question - True or false? Based on these results, it appears that the strength of muscle contraction can be controlled by varying the voltage with which the muscle is stimulated.

  4. Go to the Experiment menu and select Isotonic Contraction
    1. Hang the 0.5 g. weight on the muscle.
      Question - Does the 0.5 g. weight cause this muscle to stretch?
    2. Lower the Platform Height until the muscle is hanging freely.
    3. Stimulate the muscle with 2.0 V.
      Question - Does a muscle actually shorten during an Isotonic Contraction?
      Question - What changes during an Isotonic Contraction, the Muscle Length or the Active Force?

  5. Go to the Experiment menu and select Isometric Contraction.
    1. Set "Muscle Length" to 70 mm. Stimulate the muscle then click "Record Data."
    2. Question - Does a muscle actually shorten during an Isometric Contraction?
    3. Question - What changes during an Isometric Contraction, the Muscle Length or the Active Force?
    4. Shorten the muscle by setting "Muscle Length" to 50 mm. Stimulate the muscle then click "Record Data."
    5. Elongate the muscle by setting the Muscle Length to 90 mm. Stimulate the muscle then click "Record Data."
      Question - Based on the data, a muscle can produce the greatest amount of total force while (choose one)
      1. shortened
      2. elongated
      3. at an intermediate length
      4. none of the above (the amount of total force is not affected by the length of the muscle)

  6. Go to the Experiment menu and select Multiple Stimulus
    1. Set Muscle Length to 75 millimeters (mm.).
    2. Set the Stimuli/sec (stimuli per second) button to 1. Press "Multiple Stimulus" and observe the contraction(s), and press "Record Data."
    3. Reset the Stimuli/sec (stimuli per second) button to 50 and repeat the instructions above.
      Question - True or false? When being stimulated 50 times per second, the muscle generates more force than it does being stimulated once per second.
    4. Set the Stimuli/sec (stimuli per second) button to 100. Press "Multiple Stimulus" and observe at least five screens of contraction force data. After a few seconds, press "Record Data."
      Question - True or false? While being stimulated 100 times per second, the muscle is able to maintain its total force indefinitely.

  7. Submit the correct answers to the following questions via e mail or on paper. If using e mail:
    1. Go into your e mail software and create a new message.
    2. In the subject line, put one of the following:
      • "Mbms100muscle" if you are enrolled in the Monday lab
      • "Wbms100muscle" if you are enrolled in the Wednesday lab
      • "THbms100muscle" if you are enrolled in the Thursday lab
    3. Copy the following list of questions and paste them into the body of the e mail message.

      0. Your full name and the lab section in which you are enrolled (0 pts.) -
      1. a. How much force was generated when the muscle was stimulated with 1.0 V?
      b. How much force was generated when the muscle was stimulated with 2.0 V?
      2. True or false? Based on these results, it appears that the strength of muscle contraction can be controlled by varying the voltage with which the muscle is stimulated.
      3. Does the 0.5 g. weight cause this muscle to stretch?
      4. Does a muscle actually shorten during an Isotonic Contraction?
      5. What changes during an Isotonic Contraction, the Muscle Length or the Active Force?
      6. Does a muscle actually shorten during an Isometric Contraction?
      7. What changes during an Isometric Contraction, the Muscle Length or the Active Force?
      8. Based on the data, a muscle can produce the greatest amount of total force while (choose one)
      a. shortened
      b. elongated
      c. at an intermediate length
      d. none of the above (the amount of total force is not affected by the length of the muscle)
      9. True or false? When being stimulated 50 times per second, the muscle generates more force than it does being stimulated once per second.
      10. True or false? While being stimulated 100 times per second, the muscle is able to maintain its total force indefinitely.

    4. Type in your answers to the questions.
    5. Send the e mail to connell@sbcc.edu
    6. Also send a copy to yourself as a "receipt" and keep this receipt until credit is posted.
    7. You will receive one Plus Hour point for each correct answer except as indicated.
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Fall 2010