PhysioEx Exercise 2 Activity 3
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Western Governors University**We aren't endorsed by this school
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ANATOMY PH 201
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Biology
Date
Jan 15, 2025
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5
Uploaded by imaniward1996
10/3/21, 9:11 PMPhysioEx Exercise 2 Activity 3https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex2/act3/1/5PhysioEx Lab ReportExercise 2: Skeletal Muscle Physiology Activity 3: The Effect of Stimulus Frequency on Skeletal Muscle Contraction Name: Imani J. Ward Date: 3 October 2021 Session ID: session-f173ddc5-c87a-3924-753f-68059aa305e3 Pre-lab Quiz ResultsYou scored 100% by answering 4 out of 4 questions correctly.Experiment ResultsPredict QuestionsStop & Think QuestionsDuring a singletwitch of a skeletal muscleYou correctly answered: maximal force is never achieved.1When a skeletal muscle is repetitively stimulated, twitches can overlap each other and result in astronger muscle contraction than a stand-alone twitch. This phenomenon is known asYou correctly answered: wave summation.2Wave summation is achieved byYou correctly answered: increasing the stimulus frequency (the rate of stimulus delivery to the muscle).3Wave summation increases the force produced in the muscle. Another way to increase the forceproduced by a muscle is toYou correctly answered: increase the number of activated motor units.4Predict Question 1: As the stimulus frequency increases, what will happen to the muscle forcegenerated with each successive stimulus? Will there be a limit to this response?Your answer: As the stimulus frequency increases, the muscle force generated by each successivestimulus will remain the same.1Predict Question 2: In order to produce sustained muscle contractions with an active force value of 5.2,do you think you will need to increase the stimulus voltage?Your answer: Yes.2Was there any change in the force generated by the muscle during the second stimulated twitch?You correctly answered: Yes, the second twitch generated more muscle force.1Is the total muscle force generated by the higher frequency stimulation greater than the forcegenerated in previous stimulations?2
10/3/21, 9:11 PMPhysioEx Exercise 2 Activity 3https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex2/act3/2/5Experiment DataVoltage (v)Length (mm)StimulusActive ForcePassive ForceTotal Force8.575Single1.830.01.838.575Multiple2.880.02.888.575Multiple3.150.03.158.575Multiple4.530.04.531075Multiple4.840.04.841075Multiple5.180.05.181075Multiple5.210.05.21Voltage = 8.5 VSingle StimulusActive Force = 1.83Voltage = 8.5 VMultiple StimulusActive Force = 2.88Voltage = 8.5 VMultiple StimulusYou correctly answered: Yes, it is greater than the previous stimulations.Does the force generated by the muscle change with each additional stimulus?You correctly answered: As the stimulus frequency increased, the muscle tension generated by eachsuccessive stimulus also increased, and a limiting maximum value was observed.3
10/3/21, 9:11 PMPhysioEx Exercise 2 Activity 3https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex2/act3/3/5Active Force = 3.15Voltage = 8.5 VMultiple StimulusActive Force = 4.53Voltage = 10 VMultiple StimulusActive Force = 4.84Voltage = 10 VMultiple StimulusActive Force = 5.18
10/3/21, 9:11 PMPhysioEx Exercise 2 Activity 3https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex2/act3/4/5Voltage = 10 VMultiple StimulusActive Force = 5.21Post-lab Quiz ResultsYou scored 100% by answering 4 out of 4 questions correctly.Which of the following is notone of the ways that the body can increase the force produced by askeletal muscle?You correctly answered: application of higher voltages to the whole muscle.1When a muscle receives a stimulus frequency that causes non-overlappingtwitches to follow each otherclosely in time such that the peak tension of each twitch rises in a stepwise fashion up to a plateauvalue, the result is known asYou correctly answered: treppe.2In this experiment the isolated skeletal muscle was repetitively stimulated such that individual twitchesoverlapped with each other and resulted in a stronger muscle contraction than a standalone twitch.This phenomenon is known asYou correctly answered: wave summation.3Wave summation is achieved by4
10/3/21, 9:11 PMPhysioEx Exercise 2 Activity 3https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex2/act3/5/5Review Sheet ResultsYou correctly answered: increasing the rate of stimulus delivery (frequency) to the muscle.What is the difference between stimulus intensity and stimulus frequency?Your answer:Stimulus frequency is the amount of times the stimulus intensity is applied to the muscle.1In this experiment you observed the effect of stimulating the isolated skeletal muscle multiple times in ashort period with complete relaxation between the stimuli. Describe the force of contraction with eachsubsequent stimulus. Are these results called treppe or wave summation?Your answer:Wave summation, because there was a noted increase in frequency, which resulted in an increased in the force produced by the entire muscle.2How did the frequency of stimulation affect the amount of force generated by the isolated skeletalmuscle when the frequency of stimulation was increased such that the muscle twitches did notfullyrelax between subsequent stimuli? Are these results called treppe or wave summation? How well didthe results compare with your prediction?Your answer:This because the increase the frequency of the stimulus to reach both.3To achieve an active force of 5.2, did you have to increase the stimulus voltage above 8.5 volts? If not,how did you achieve an active force of 5.2? How well did the results compare with your prediction?Your answer:The stimulus had an increased frequency at which it stimulated the muscle fiber, once I increased the voltage to 10.4Compare and contrast frequency-dependent wave summation with motor unit recruitment (previouslyobserved by increasing the stimulus voltage). How are they similar? How was each achieved in theexperiment? Explain how each is achieved in vivo.Your answer:The frequency-dependent wave summation and the motor unit recruitment are similar and achieved in the same way; both rely on increased frequency to the stimuli for both of them to be reached.5