As the stimulus voltage was increased in this activity, which of the following occurred? What is the minimum voltage needed to generate active force in the skeletal muscle? describes the relationship between stimulus frequency and muscle tension? At what stimulus frequency was maximal tetanic tension developed?. Increasingly, the force gets stronger with the higher stimulus voltage until it plateaus at They became depolarized and developed active force. Each of the . As the stimulus voltage is increased, the amount of force in the muscle also increases. What is the difference between stimulus intensity and stimulus frequency? Indicate what type of force was developed by the isolated skeletal muscle in.
The muscle twitches overlapped. To achieve an active force of 5. If not, how did you achieve an active force of 5. No, in order to achieve an active force of 5. This is known as wave summation.
Compare and contrast frequency-dependent wave summation with motor unit recruitment previously observed by increasing the stimulus voltage. How are they similar? How was each achieved in the experiment? Explain how each is achieved in vivo.
Frequency-dependent wave summation is dependent upon stimulation by the nervous system. The motor recruitment depends upon the number of motor fibers available Activity 4 Tetanus in Isolated Skeletal Muscle 1. Describe how increasing the stimulus frequency affected the force developed by the isolated whole skeletal muscle in this activity. As the stimulus frequency was increased, the forces increased also. Indicate what type of force was developed by the isolated skeletal muscle in this activity at the following stimulus frequencies: Beyond what stimulus frequency is there no further increase in the peak force?
What is the muscle tension called at this frequency? When a skeletal muscle fatigues, what happens to the contractile force over time? Once the muscle reaches maximum tetanic tension, there is no longer an increase in force generated.
At this stage, the muscle is fatigued and contractile force decreases 1. Turning the stimulator off allows a small measure of muscle recovery. Thus, the muscle will produce more force for a longer time period if the stimulator is briefly turned off than if the stimuli were allowed to continue without interruption.
Explain why this might occur. Turning the stimulator off, creates a period of rest. This allows concentrations intracellular concentrations of lactic acid to decrease. With that at a decreased level, the length of time for maximum tension increases. List a few ways that humans could delay the onset of fatigue when they are vigorously using their skeletal muscles. We cold delay onset fatigue by doing multiple sets of low repetition in exercise, allowing for multiple times of rest and a healthy diet and good amount of exercise.
What happens to the amount of total force the muscle generates during the stimulated twitch? The total amount of force increases when the muscle is lengthened or shortened.
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What is the key variable in an isometric contraction of a skeletal muscle? Muscle length is the key variable in isometric contraction b. Active force data changes as the resting muscle length changes. When the resting length is shortened, the active force increases. When the resting length is lengthened, the active force decreases. The change of active force is caused by the amount of myosis bound to actin. What skeletal muscle lengths generated passive force? If you were curling a 7-kg dumbbell, when would your bicep muscles be contracting isometrically?
When the bicep muscle remains at a fixed length the bicep muscles will be contracting isometrically. When one is extending their arm downwards and when lifting the dumbbell to the raised position is when the muscles will be contracting isotonically. Explain why the latent period became longer as the load became heavier in the experiment.
The latent period occurs when there is a rise in muscle tension but no movement of the muscle.
The latent period increases as the weight of the load gets heavier, it is necessary for force to be generated by the muscle. Explain why the shortening velocity became slower as the load became heavier in this experiment. Maximal shortening velocity is only occurring with minimal load. Move the vertical green curosr to the end of the twitch, leave the red cursor where it is.
The difference in the x coordinates is now the relaxation duration, which may be very different from the contraction duration. Example of measuring the muscle twitch 2. Effect of Stimulus Strength. Use the data from Part 1. Single Muscle Twitch as your first data point for Stimulus Strength voltage vs. Continue increasing the voltage in small increments Volts to obtain 4 other data points, but not to the point of invoking real pain. If the trigger is reaching the end of its travel, increase the spring tension or substitue a stiffer spring, then repeat the experiment.
Measure the strength displacementcontraction duration, and relaxation duration for each twitch. Record these numbers along with the voltage of each twitch measured. Grasp the pistol grip as before. Use a voltage that gives a minimal, but recordable, twitch.
Types of Muscles Essay
The experiment may have to be repeated several times to get it right. Determine the time interval between stimuli as measured from the peak of one twitch to the peak of the next twitch seconds before summation occurred. Determine the time interval between stimuli measured from the peak of one twitch to teh peak of the next twitch seconds just before tetany occured.
Measure the displacement strength of one twitch that occurred before summation. Measure the displacement strength of the tetanic contraction. Fatigue and Muscle Relaxation Stimulator settings: Click the run arrow, then quickly turn the stimulator to a tetanizing frequency, as determined earlier. Determine the length of time for relaxation of the muscle. Rest for a few minutes. Have the subject contract the same finger rapidly and vigorously for 2 minutes.