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so... Now i have Exercise 2 can you help me with this one?

Single Stimulus
Activity 1:  Identifying the Latent Period

1.   How long is the latent period?       2.78msec
2.   Does the latent period change with different stimulus voltages? NO

Activity 2:  Identifying the Threshold Voltage

1.   What do you see in the Active Force display?
2.   What is the threshold voltage?           .8V
3.   How does the graph generated at the threshold voltage differ from the graphs generated at voltages below the threshold?

Activity 3:  Effect of Increases in Stimulus Intensity

1.   How did the increases in voltage affect the peaks in the tracings?
2.   How did the increases in voltage affect the amount of active force generated by the muscle?
3.   What is the voltage beyond which there were no further increases in active force? Maximal voltage:            V
4.   Why is there a maximal voltage?  What has happened to the muscle at this voltage?  
5.   An individual muscle fiber follows the all-or-none principle—it will either contract 100% or not at all.  Does the muscle we are working with exhibit the all-or-none principle?  Why or why not?

Multiple Stimulus
Activity 4:  Treppe

1.   What do you observe?

Activity 5:  Summation

1.   What is the active force of the contraction?       gms
2.   What is the active force now?         gms
3.   Was there any change in the force generated by the muscle?
4.   Was there any change in the force generated by the muscle?
5.   Why has the force changed?
6.   Do you see the same pattern of changes in the force generated?
7.   Does the force generated change with each additional stimulus?  If so, why?

Activity 6:  Tetanus

1.   What begins to happen at around 80 msec?
2.   What is this condition called?
3.   How does the trace at 130 stimuli/sec compare with the trace at 50 stimuli/sec?
4.   What is this condition called?
5.   At what stimulus frequency is there no further increase in force?
6.   What is this stimulus frequency called?

Activity 7:  Fatigue

1.   In fatigue, what happens to force production over time?

Isometric and Isotonic Contractions
Activity 8:  Isometric Contractions

1.   Looking at your graph, what muscle lengths generated the most active force? (provide a range)                to                 mm
2.   At what muscle length does passive force begin to play less of a role in the total force generated by the muscle?               mm
3.   Looking at your graph, at what muscle length does passive force begin to play a role in the total force generated by the muscle?               mm
4.   The graph shows a dip at muscle length = 90 mm.  Why is this?
5.   What is the key variable in an isometric contraction?

Activity 9:  Isotonic Contractions

1.   How much time does it take for the muscle to generate 0.5 grams of force?         msec
2.   At what point in the trace does the muscle shorten?
3.   You can observe from the trace that the muscle is rising in force before it reaches the plateau phase.  Why doesn’t the muscle shorten prior to the plateau phase?
4.   Did it take any longer for the muscle to reach the force it needed to move the weight?
5.   How does this trace differ from the trace you generated with the 0.5 gram weight attached?      
6.   Examine the plot data and your numerical data.  At what weight was the velocity of contraction the fastest?         grams
7.   What happened when you attached the 2.0 gram weight to the muscle and stimulated the muscle?  How did this trace differ from the other traces?  What kind of contraction did you observe?
8.   What kind of trace did you get?
9.   What was the force of the contraction?         grams
10.   With the 1.0 gram weight, what kind of trace did you get?  What was the force of the contraction?       grams
11.   With the 1.5 gram weight, what kind of trace did you get?  What was the force of the contraction?       grams
12.   With the 2.0 gram weight, what kind of trace did you get?  What was the force of the contraction?       grams
13.   Describe your four tracings and explain what has happened in each of them.
14.   What muscle length(s) generated the fastest contraction velocity?

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Your Question: to Activity 7:  Fatigue

1.   In fatigue, what happens to force production over time?


Answer: ATP is used up faster than it is produced
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Single Stimulus
Activity 1:  Identifying the Latent Period

1.   How long is the latent period?    2.78   msec
2.   Does the latent period change with different stimulus voltages? No

Activity 2:  Identifying the Threshold Voltage

1.   What do you see in the Active Force display?  0.02 is displayed
2.   What is the threshold voltage?           0.8V
3.   How does the graph generated at the threshold voltage differ from the graphs generated at voltages below the threshold? At 0.8V the active force increases slightly higher than in the previous eight tests ranging from 0.0-0.7.

Activity 3:  Effect of Increases in Stimulus Intensity

1.   How did the increases in voltage affect the peaks in the tracings? It seems that no matter the voltage the muscle peaks at the same time.
2.   How did the increases in voltage affect the amount of active force generated by the muscle? There was a steady increase in the Active Force until the voltage reached 8.5 and then leveled off.
3.   What is the voltage beyond which there were no further increases in active force? Maximal voltage:           8.5V
4.   Why is there a maximal voltage? All of the muscle fibers have fully contracted. What has happened to the muscle at this voltage? It is in the contraction phase. 
5.   An individual muscle fiber follows the all-or-none principle—it will either contract 100% or not at all.  Does the muscle we are working with exhibit the all-or-none principle? I would say both yes and no.  Why or why not? When the muscle was stimulated at 0.5 the muscle did not contract, as in there was no Active Force.  However, during this experiment the muscle did contract between the voltage range of 1.0-10.0.  The muscle only contracted if there was enough stimulus to create active force.

Multiple Stimulus
Activity 4:  Treppe

1.   What do you observe? The muscle follows all three phases, Latent, Contraction and Relaxation, each time the single stimulus button is clicked.

Activity 5:  Summation

1.   What is the active force of the contraction?  1.83gms
2.   What is the active force now?    2.89gms
3.   Was there any change in the force generated by the muscle? Yes, the force increased.
4.   Was there any change in the force generated by the muscle? Yes, the force increased.
5.   Why has the force changed? Because the muscle did not have a chance to relax, resulting in a stronger muscle contraction.
6.   Do you see the same pattern of changes in the force generated? Although the Active Force is lower in this experiment the pattern remains the same.
7.   Does the force generated change with each additional stimulus? Yes. If so, why? The muscle was stimulated in rapid succession, which causes larger contractions, this is called wave summation.

Activity 6:  Tetanus

1.   What begins to happen at around 80 msec? during the contractions the active force generated during the stimulations begins to plateau.
2.   What is this condition called? Unfused Tetanus.
3.   How does the trace at 130 stimuli/sec compare with the trace at 50 stimuli/sec? The twitches are closer together, so much so that they are undistinguishable from each other.
4.   What is this condition called? Fused Tetanus
5.   At what stimulus frequency is there no further increase in force? 146
6.   What is this stimulus frequency called? Maximal tetanic tension.

Activity 7:  Fatigue

1.   In fatigue, what happens to force production over time? The force production slowly decreases until it reaches zero.

Isometric and Isotonic Contractions
Activity 8:  Isometric Contractions

1.   Looking at your graph, what muscle lengths generated the most active force? (provide a range)        70   to 80 mm
2.   At what muscle length does passive force begin to play less of a role in the total force generated by the muscle?   70     mm
3.   Looking at your graph, at what muscle length does passive force begin to play a role in the total force generated by the muscle?    80   mm
4.   The graph shows a dip at muscle length = 90 mm.  Why is this? Because the most active force is generated at the previous length of 80 mm
5.   What is the key variable in an isometric contraction? The amount of force of an object is greater than the amount of force that is applied the muscle contracts isometrically. 

Activity 9:  Isotonic Contractions

1.   How much time does it take for the muscle to generate 0.5 grams of force? 3.77 msec
2.   At what point in the trace does the muscle shorten? At the beginning of the plateau.
3.   You can observe from the trace that the muscle is rising in force before it reaches the plateau phase.  Why doesn’t the muscle shorten prior to the plateau phase? Because enough force has not been generated to move the load.
4.   Did it take any longer for the muscle to reach the force it needed to move the weight? No.
5.   How does this trace differ from the trace you generated with the 0.5 gram weight attached?  More Force had to be generated to lift the weight.   
6.   Examine the plot data and your numerical data.  At what weight was the velocity of contraction the fastest?   1.0      grams
7.   What happened when you attached the 2.0 gram weight to the muscle and stimulated the muscle? When the muscle reached the peak of the contraction phase the muscle immediately entered the relaxation phase. How did this trace differ from the other traces? The muscle did not plateau as it did at the other weights. What kind of contraction did you observe? An Isotonic Contraction.
8.   What kind of trace did you get? The trace started at a force of 0.5, there was no change to the trace, it remained a flat line.
9.   What was the force of the contraction?    Passive 0.5     grams
10.   With the 1.0 gram weight, what kind of trace did you get? The trace started at a force of 1.0, there was no change to the trace, it remained a flat line. What was the force of the contraction?  Passive 1.00 grams
11.   With the 1.5 gram weight, what kind of trace did you get? The trace started at a force of 1.5, there was no change to the trace, it remained a flat line.  What was the force of the contraction?   Passive 1.51  grams
12.   With the 2.0 gram weight, what kind of trace did you get? The trace started at a force of 1.75, there was a slight increase to 1.86 and then the trace leveled back off at 1.75. What was the force of the contraction?  Active 0.11/passive 1.75 for a total of 1.86 grams
13.   Describe your four tracings and explain what has happened in each of them. For the weight of 0.5 the trace started at a force of 0.5, there was no change to the trace, it remained a flat line.  For the 1.0 trace, the trace started at a force of 1.0, there was no change to the trace, it remained a flat line.  For the 1.5 trace, the trace started at a force of 1.5, there was no change to the trace, it remained a flat line.  For the 2.0 trace, the trace started at a force of 1.75, there was a slight increase to 1.86 and then the trace leveled back off at 1.75.
14.   What muscle length(s) generated the fastest contraction velocity? 70 and 80 mm.

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From activity 3, Describe the effect of increasing the voltage. What happened to the force generated and why did this change occur?
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From activity 3, Describe the effect of increasing the voltage. What happened to the force generated and why did this change occur?

Force generated increased because the total number of cells contracting is increased.
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here's a key
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Yeah, but it can't be downloaded, you have to pay. I hate that site Pouting Face
Biology!
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well, it will help those who just need the answer =D
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well, it will help those who just need the answer =D

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Biology!
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Can anyone direct me to where i can find the answers to physioex 8.0 A&P exercise 2.  Neutral Face
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I can help with a few...

2-1: What was the effect of thyroxine on the normal rat's metabolic rate? How does it compare to the normal rat's baseline metabolic rate? On the normal rat, the metabolic rate after thyroxine injection is faster than the baseline metabolic rate.

2-2: Why was this effect seen? The action of thyroxine is to increase the metabolic rate of all cells.

2-3: What was the effect of thyroxine on the thyroidectomized rat's metabolic rate? How does it compare to the thyroidectomized rat's baseline metabolic rate? On the thyroidectomized rat, the metabolic rate after thyroxine injection is faster than the baseline metabolic rate.

2-4: Why was this effect seen? The injected thyroxine compensated for the thyroxine lost when the thyroid was removed.

2-5: What was the effect of thyroxine on the hypophysectomized rat's metabolic rate? How does it compare to the hypophysectomized rat's baseline metabolic rate? On the hypophysectomized rat, the metabolic rate after thyroxine injection is faster than the baseline metabolic rate.

2-6: Why was this effect seen? The injected thyroxine compensated for the thyroxine lost when the pituitary gland was removed. The pituitary gland did not produce TSH, therefore the thyroid gland did not produce thyroxine.
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