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Activity:
Name:
Instructor:
Date:
Twitch Contractions and Summation
Katrelle Bond
Rachel Waite
November 7, 2014
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: increases. Materials and Methods
Measurement of Threshold Stimulus
1. Dependent Variable contraction force
2. Independent Variable stimulation voltage
3. Controlled Variables muscle fiber length; frequency of stimulation; temperature
Effect of Muscle Length on Contraction
1. Dependent Variable contraction force
2. Independent Variable muscle fiber length
3. Controlled Variables temperature; frequency of stimulation; stimulation voltage
Effect of Stimulation Frequency on Contraction
1. Dependent Variable contraction force
2. Independent Variable frequency of stimulation
3. Controlled Variables stimulation voltage; temperature
4. What structure was stimulated to cause a muscle contraction? undefined 5. Explain why the temperature of the water bath was 35ºC (95 ºF). undefined 6. At a stimulation frequency of 15 Hz how many stimuli were there per second?
undefined
Results
Table 4: Measurement of Threshold Stimulus
Force
(gf)(Motor neuron 1)
100 mV
0
200 mV
0
Voltage (mV)
300 mV
0
400 mV
0.102
500 mV
0.102
Effect of Stimulation Value on Twitch Contraction Force
1. What is the threshold stimulus?
The minimal voltage that induces an action potential
2. What is the maximum force generated at the threshold stimulus?
0.102
3. How does increasing voltage above threshold stimulus affect force development? undefined Table 5: Muscle Length and Contraction Force
Force( gf )(
Motor
neuron 1)
Trial 1
Trial 2
Trial 3
Averages
6.5
7.0
7.5
8.0
0.084
0.083
0.084
0.084
0.091
0.09
0.091
0.091
0.1
0.1
0.1
0.1
0.102
0.102
0.102