Lab Twitch Essay

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LABORATORY REPORT Activity: Twitch Contractions and Summation Name: Danielle Emerson Instructor: Dr. Horn Date: 07.21.2015 Predictions Effect of Muscle Fiber Length on Contraction 1. As muscle fiber length increases contraction force increases Effect of Stimulation Frequency on Contraction 2. As the frequency of stimulation increases, the force of contraction: decreases Materials and Methods Measurement of Threshold Stimulus Dependent Variable contraction force Independent Variable stimulation voltage Controlled Variables temperature, frequency of stimulation, muscle fiber length Effect of Muscle Length on Contraction Dependent Variable contraction force Independent Variable muscle fiber length Controlled Variables temperature, stimulation voltage, frequency of stimulation Effect of Stimulation Frequency on Contraction Dependent Variable contraction force Independent Variable frequency of stimulation Controlled Variables temperature, stimulation voltage 4. What structure was stimulated to cause a muscle contraction? The motor unit was stimulated 5. Explain why the temperature of the water bath was 35 C (95 F). The water bath was 35ºC because is near the mouseâ##s normal body temperature. Laboratory Report/ Danielle Emerson/ Twitch Contractions and Summation/ Dr. Horn/ 07.21.2015/ Page [1] of [4] 6. At a stimulation frequency of 15 Hz how many stimuli were there per second? There are 15 pulses (stimuli) per second. Results Table 4: Measurement of Threshold Stimulus Force (gf)(Motor neuron 1) 100 mV 0 Voltage (mV) 300 mV 0 200 mV 0 400 mV 0.080 500 mV 0.080 Effect of Stimulation Value on Twitch Contraction Force 1. What is the threshold stimulus? 400mV 2. What is the maximum force generated at the threshold stimulus? The maximum force generated was 0.084 gf.

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