Skeletal Muscle: a Study of Skeletal Muscle Contraction Mechanism in Fogs and the Various Factors Affecting It
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Experiment 2: Skeletal Muscle
Frog skeletal muscle is used as an animal model to study muscle contraction. The objectives of this experiment is to demonstrate the physiological responses of skeletal muscle to electrical stimuli using frog gastrocnemius, to understand twitch, summation, tetanus and fatigue, to investigate the relationship between initial tension and force of contraction, to explore the differences between human and frog skeletal muscle. The threshold voltage is 0.4V. The minimum voltage required to give a maximal response is 5V. Stimulus voltages and muscle response shows a linear relationship from 0.4V to 5V and reaches plateau at 6V. The optimal initial tension at which maximum force of contraction could be…show more content… Furthermore, the stimulation frequency and intensity of twitch, summation, and tetanus of frog and human skeletal muscles are compared.
MATERIALS AND METHODS
Procedures in “Lab 2 - Skeletal Muscle” handout was followed. For section 2, the muscle tension is set to 4-5 g. For section 5 and 6, data collected does not show the effects well, data from Sally Yu Shi and Mashriq Alganabi was used for these two sections respectively. For section 7, a student volunteer was used in the demonstration.
RESULTS AND DISCUSSION
1. Relationship between Stimulus Voltage and Muscle Response
[pic] The relationship between stimulus voltage and muscle response is demonstrated in Figure 1a and 1b. Force of contraction is used to measure the muscle response due to stimulation. In figure 1b, the mean maximum muscle response is calculated by averaging the maximum amplitudes in grams from the 3 single stimuli, then converting force of contraction from gram to Newton using F=ma, where a=9.8m/s2. Above figures show that as the voltage of the stimulus increases, the strength of the twitch increases. The threshold voltage required to produce a twitch response is 0.4 V. The minimum voltage required to give a maximal response is 5 V. There is an increase in muscle response from 0.4 V to 5V. Increasing voltage of the stimuli beyond 5 V does not further increase the twitch response significantly. The contraction