PhysioEx Exercise 2 Activity 7 - Rickey Maung

2/11/2022 PhysioEx Exercise 2 Activity 7 https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex2/act7/ 1/5 PhysioEx Lab Report Exercise 2: Skeletal Muscle Physiology Activity 7: Isotonic Contractions and the Load-Velocity Relationship Name: Rickey Maung Date: 11 February 2022 Session ID: session-bb113d8c-84b6-ccaf-1fb3-92fcff54a7da Pre-lab Quiz Results You scored 100% by answering 5 out of 5 questions correctly. Experiment Results Predict Question Stop & Think Question During an isotonic concentric contraction, the You correctly answered: force generated by the muscle is greater than the weight of the attached load. 1 During an isotonic concentric contraction You correctly answered: the latent period increases with heavier loads. 2 During the latent period for an isotonic concentric contraction You correctly answered: cross bridges cycle and, when muscle tension exceeds the load, muscle shortening occurs. 3 Muscle shortening velocity You correctly answered: decreases with heavier loads. 4 An isotonic contraction of a muscle is one in which You correctly answered: the length of the muscle changes. 5 Predict Question: As the load on the muscle increases , what will happen to the latent period, the shortening velocity, the distance that the weight moves, and the contraction duration? Your answer: The latent period will decrease, the shortening velocity will decrease, the distance will increase, and the contraction duration will increase. 1

2/11/2022 PhysioEx Exercise 2 Activity 7 https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex2/act7/ 2/5 Experiment Data Voltage (v) Length (mm) Weight (g) Velocity* (mm/ms) Distance Lifted (mm) Time (contracting) Time (relaxing) Twitch Duration (total) 8.5 75 0.5 0.100 4.0 40.00 38.00 78.00 8.5 75 1.0 0.057 2.0 35.00 14.00 49.00 8.5 75 1.5 0.022 0.5 23.00 7.00 30.00 8.5 75 2.0 0.000 0.0 0.00 0.00 0.00 *Distance divided by time (contracting). weight = 0.5 g duration of twitch = 78.00 msec velocity = 0.100 mm/msec distance lifted = 4.0 mm weight = 1.0 g duration of twitch = 49.00 msec velocity = 0.057 mm/msec distance lifted = 2.0 mm weight = 1.5 g duration of twitch = 30.00 msec velocity = 0.022 mm/msec distance lifted = 0.5 mm What kind of contraction did you observe when you attached the 2.0 gram weight to the skeletal muscle and stimulated a contraction? You correctly answered: isometric. 1

2/11/2022 PhysioEx Exercise 2 Activity 7 https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex2/act7/ 4/5 Review Sheet Results You correctly answered: 1.5-g weight. Which weight did the muscle contraction move the greatest distance? You correctly answered: 0.5-g weight. 3 Which of the weights allowed the longest duration of muscle contraction? You correctly answered: 0.5-g weight. 4 An isotonic contraction of a muscle is one in which You correctly answered: the length of the muscle changes. 5 When lifting a heavy load You correctly answered: the muscle shortening velocity is decreased in comparison with lighter loads. 6 If you were using your bicep muscles to curl a 7-kg dumbbell, when would your muscles be contracting isotonically? You did not answer this question. 1 Explain why the delay between muscle stimulation and load movement became longer as the load became heavier in the experiment. How well did the results compare with your prediction? You did not answer this question. 2 Explain why the shortening velocity became slower as the load became heavier in this experiment. How well did the results compare with your prediction? You did not answer this question. 3 Describe how the shortening distance changed as the load became heavier in this experiment. How well did the results compare with your prediction? You did not answer this question. 4 Explain why it would take you longer to perform 10 repetitions lifting a 10-kg weight than it would to perform the same number of repetitions with a 5-kg weight. You did not answer this question. 5 Describe what would happen in the following experiment: A 2.5-g weight is attached to the end of the isolated whole skeletal muscle used in these experiments. Simultaneously, the 6

2/11/2022 PhysioEx Exercise 2 Activity 7 https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex2/act7/ 5/5 muscle is maximally stimulated by 8.5 volts and the platform supporting the weight is removed. Will the muscle generate force? Will the muscle change length? What is the name for this type of contraction? You did not answer this question.