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Biology-Related Homework Help General Biology Topic started by: dkrimmer2040 on May 6, 2011



Title: Name each phase of a typical muscle twitch, and, on the following line, describe
Post by: dkrimmer2040 on May 6, 2011
Need help with PhsioEx 8.o, Lab Exercise 2, Review Sheet

Electrical Stimulation
1. Name each phase of a typical muscle twitch, and, on the following line, describe what is happening in each phase.
a.

b.

c.

2. In Activity 2, how long was the latent period? __________ msec
Describe the chemical changes that are occurring during this period.


The Graded Muscle Response to Increased Stimulus Intensity
3. From Activity 3, describe the effect of increasing the voltage. What happened to the force generated and why did this change occur?

 
4. How does this change occur in vivo?


5. In Activity 4, you looked at the effect of stimulating the muscle multiple times in a short period with complete relaxation between the stimuli.
Describe the force of contraction with each subsequent stimulus.


6. Describe the chemical changes that are thought to correlate to this change in vivo.


7. In Activity 5, what was the effect of increasing the frequency of stimulation?


8. Compare and contrast wave summation with recruitment (multiple motor unit summation). How are they similar? How was each achieved in the simulation?


9. Explain how wave summation and recruitment are achieved in vivo.


10. For Activity 6, explain how you were able to achieve smooth contraction at a given force level.

11. In Activity 7, explain why the force of the muscle decreased over time during uninterrupted stimulation. Describe the multiple causes of this phenomenon, which occurs in vivo with prolonged use of a muscle.


Isometric Contraction
12. In Activity 8, at what length of the muscle does the passive force start to increase?

13. Explain what happens to the active force with an increase in the muscle length.

14. Explain what happens to the active force with a decrease in the muscle length.

15. Explain what is happening in the sarcomere that results in the changes in total force when the muscle length changes.

Isotonic Contraction
16. In Activity 9, which weight resulted in the highest initial velocity of shortening?
17. Explain the relationship between the amount of resistance and the initial velocity of shortening.

18. Explain why it will take you longer to perform 10 repetitions lifting a 20-pound weight than it would to perform the same number of repetitions with a 5-pound weight.


Title: Re: Help!
Post by: duddy on May 7, 2011
1. A) latent period

The muscle cells are biochemically preparing to contract, includes all biochemical events from acetylcholine binding to sarcolemma through cross-bridge formation.

B) contraction phase

Sarcomeres are shortening, causing the muscle cells to contract in turn, which causes a force increase.

C) relaxation phase

Sarcomeres are lengthening due to relaxation (cross-bridge broken); force is falling.

2. 2.78 msec ... Acetylcholine binds to sarcolemma; sarcolemma then T-tubules depolarize; Ca++ released from terminal cisternae travels along SR, is release into sarcoplasm, then binds to troponin to unblock tropomyosin binding sites allowing cross-bridge formation (i.e., myosin heads bind to actin).

3. Force generated increased because the total number of cells contracting is increased.

4. In vivo increasing force is achieved by neural activation of an increasingly large number of motor units serving the muscle.

Please contribute further to obtain for assistance...


Title: Re: Help!
Post by: jmjjmj on Jun 22, 2011
8.Muscles are stimulated to contract by electrical signals, usually from the brain. These waves of electricity can be piled on top of each other, causing increased strength and duration of muscle contraction. Motor reqruitment involves sending signals to multiple parts of the muscle at once, resulting in one quick, strong contraction. Summation is similar in that it increases contractile force.

13. Force decreases as muscle length is increased beyond the optimal length. The muscle has two different fibers, actin and myosin. They pull on each other to contract the muscle. As the muscle length increases less of these fibers are in contact with eachother, decreasing the force the muscle can create.

14. Force decreases as muscle lenght is decreased beyond the optimal length. This time the fibers are piling up on each other making it more difficult for the muscle to contract.

15. Included in 13 and 14, sarcomere length changes and causes unwanted changes in the interaction between these two fibers.

17. This is common sense, if there is more resistance on a muscle it will not be able to contract as fast as the muscle with less resistance.

18. Our bodies were designed with speed in mind. Nearly all of our muscles are at a mechanical disadvantage. Meaning, we sacrifice force for speed. Any increase in resistance to contraction is multiplied because of this set up.


Title: Re: Help!
Post by: nate_1234 on Jul 6, 2011
Thanks for the help. 


Title: Re: Help!
Post by: ugh on Jul 29, 2011
 From Activity 3, describe the effect of increasing the voltage. What happened to the force generated and why did this change occur?

 


Title: Re: Help!
Post by: lewis on Jul 29, 2011
Start a new topic!

Force generated increased because the total number of cells contracting is increased.


Title: Re: Help!
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Title: Re: Name each phase of a typical muscle twitch, and, on the following line, describe
Post by: krisrob12 on Oct 26, 2011
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Title: Re: Name each phase of a typical muscle twitch, and, on the following line, describe
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Title: Re: Name each phase of a typical muscle twitch, and, on the following line, describe
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Title: Re: Name each phase of a typical muscle twitch, and, on the following line, describe
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Title: Re: Name each phase of a typical muscle twitch, and, on the following line, describe
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Title: Re: Name each phase of a typical muscle twitch, and, on the following line, describe
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Title: Re: Name each phase of a typical muscle twitch, and, on the following line, describe
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Title: Re: Name each phase of a typical muscle twitch, and, on the following line, describe
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Title: Re: Name each phase of a typical muscle twitch, and, on the following line, describe
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Title: Re: Name each phase of a typical muscle twitch, and, on the following line, describe
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Title: Re: Name each phase of a typical muscle twitch, and, on the following line, describe
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Title: Re: Name each phase of a typical muscle twitch, and, on the following line, describe
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Title: Re: Name each phase of a typical muscle twitch, and, on the following line, describe
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Title: Re: Name each phase of a typical muscle twitch, and, on the following line, describe
Post by: Kellishous1 on Apr 2, 2014
1. A) latent period

The muscle cells are biochemically preparing to contract, includes all biochemical events from acetylcholine binding to sarcolemma through cross-bridge formation.

B) contraction phase

Sarcomeres are shortening, causing the muscle cells to contract in turn, which causes a force increase.

C) relaxation phase

Sarcomeres are lengthening due to relaxation (cross-bridge broken); force is falling.

2. 2.78 msec ... Acetylcholine binds to sarcolemma; sarcolemma then T-tubules depolarize; Ca++ released from terminal cisternae travels along SR, is release into sarcoplasm, then binds to troponin to unblock tropomyosin binding sites allowing cross-bridge formation (i.e., myosin heads bind to actin).

3. Force generated increased because the total number of cells contracting is increased.

4. In vivo increasing force is achieved by neural activation of an increasingly large number of motor units serving the muscle.

Please contribute further to obtain for assistance...
5.Force generated increased because the total number of cells contracting is increased.


Title: Re: Name each phase of a typical muscle twitch, and, on the following line, describe
Post by: Quasikitty on Apr 10, 2014
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Title: Re: Name each phase of a typical muscle twitch, and, on the following line, describe
Post by: jen42591 on Mar 6, 2015
contribute
THanks for the help