Tetanus and Muscle Force: Insights from PhysioEx Activity 4

10/27/22, 3:57 PM PhysioEx Exercise 2 Activity 4 https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex2/act4/ 1/5 PhysioEx Lab Report Exercise 2: Skeletal Muscle Physiology Activity 4: Tetanus in Isolated Skeletal Muscle Name: Selvana Labib Date: 27 October 2022 Session ID: session-2fd2f051-25b6-098c-9df6-a68d7f66d4b9 Pre-lab Quiz Results You scored 100% by answering 3 out of 3 questions correctly. Experiment Results Predict Question Stop & Think Questions Stimulus frequency refers to You correctly answered: the rate that stimulating voltage pulses are applied to an isolated whole skeletal muscle. 1 Which of the following distinguishes a state of unfused tetanus from a state of complete (fused) tetanus? You correctly answered: Muscle tension increases and decreases during a state of unfused tetanus. 2 When the stimulus frequency reaches a value beyond which no further increases in force are generated by the muscle, the muscle has reached its You correctly answered: maximal tetanic tension. 3 Predict Question: As the stimulus frequency increases further, what will happen to the muscle tension and twitch appearance with each successive stimulus? Will there be a limit to this response? Your answer: As the stimulus frequency increases, the muscle tension generated by each successive stimulus will increase. There will be no limit to this increase. 1 What begins to happen at around 80 msec? You correctly answered: unfused tetanus develops. 1 How does the trace at 130 stimuli/sec compare with the trace at 50 stimuli/sec? 2

10/27/22, 3:57 PM PhysioEx Exercise 2 Activity 4 https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex2/act4/ 2/5 Experiment Data Voltage (v) Length (mm) Stimuli/sec Act. Force Pass. Force Total Force 8.5 75 50 5.12 0 5.12 8.5 75 130 5.88 0 5.88 8.5 75 140 5.91 0 5.91 8.5 75 150 5.95 0 5.95 Stimuli/sec = 50 at 8.5 V Stimuli/sec = 130 at 8.5 V You correctly answered: Fused tetanus develops at this greater stimulus frequency. How do the traces with 146-150 stimuli per second compare with the trace at 130 stimuli per second? You correctly answered: Maximal tetanic tension develops with these very high stimulation frequencies. 3

10/27/22, 3:57 PM PhysioEx Exercise 2 Activity 4 https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex2/act4/ 3/5 Stimuli/sec = 140 at 8.5 V Stimuli/sec = 150 at 8.5 V

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10/27/22, 3:57 PM PhysioEx Exercise 2 Activity 4 https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex2/act4/ 4/5 Post-lab Quiz Results You scored 100% by answering 3 out of 3 questions correctly. Review Sheet Results The term tetanus refers to You correctly answered: sustained muscle tension due to very frequent stimuli. 1 Which of the following distinguishes a state of unfused tetanus from a state of complete (fused) tetanus? You correctly answered: Muscle tension increases and decreases between different values for an unfused tetanus. 2 When the stimulus frequency reaches a value beyond which no further increases in force are generated by the muscle, the muscle has reached its You correctly answered: maximal tetanic tension. 3 Describe how increasing the stimulus frequency affected the force developed by the isolated whole skeletal muscle in this activity. How well did the results compare with your prediction? Your answer: Increasing the stimulus frequency affected the force developed by the isolated whole skeletal muscle in this activity as it lead to an increase in active force generated by the whole skeletal muscle. Active force began to plateau and maximal teutonic tension occurred. 1 Indicate what type of force was developed by the isolated skeletal muscle in this activity at the following stimulus frequencies: at 50 stimuli/sec, at 140 stimuli/sec, and above 146 stimuli/sec. Your answer: 50 stimuli/sec : unused tetanus 140 stimuli/sec : complete fused tetanus 146+ stimulus/sec : maximal tetanic tension. 2 Beyond what stimulus frequency is there no further increase in the peak force? What is the muscle tension called at this frequency? Your answer: 3

10/27/22, 3:57 PM PhysioEx Exercise 2 Activity 4 https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex2/act4/ 5/5 maximal tetanic tension was achieved at 150 stimuli/sec. There was no further increase in the peak force when the stimulus frequency was above 140 stimuli/sec as the force developed was at it's maximum tetanic tension.

PhysioEx Exercise 2 Activity 4

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