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lcv123 lcv123
wrote...
Posts: 9
Rep: 1 0
13 years ago
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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11 Replies
Replies
wrote...
13 years ago
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
Answer verified by a subject expert
AzReaperAzReaper
wrote...
Posts: 4
Rep: 2 0
12 years ago
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This verified answer contains over 1410 words.

Related Topics

wrote...
12 years ago
From activity 3, Describe the effect of increasing the voltage. What happened to the force generated and why did this change occur?
wrote...
Valued Member
Educator
12 years ago
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.
wrote...
12 years ago
here's a key
wrote...
12 years ago
http://www.docstoc.com/docs/39141013/Skeletal-Muscle-Physiology
wrote...
12 years ago

Yeah, but it can't be downloaded, you have to pay. I hate that site Pouting Face
Biology!
wrote...
12 years ago
well, it will help those who just need the answer =D
wrote...
12 years ago
well, it will help those who just need the answer =D

lol no doubt but you know what I mean Face with Stuck-out Tongue
Biology!
wrote...
12 years ago
Can anyone direct me to where i can find the answers to physioex 8.0 A&P exercise 2.  Neutral Face
wrote...
12 years ago
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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