EXERCISE 2: Skeletal Muscle Physiology Worksheet from Physio 8

Specific questions only.

I posted 41 questions!

1 or 2 would be more appropriate. This is a free service, so be more considerate.

I understand its free...

was I being inconsiderate?? I'm totally lost here.

I believe you are wanting us to do this entire exercise for you. That is not something we do. We will help you with a few questions on a particular activity. I suggest you use the search feature of the forum and you will locate some of the activity answers you are looking for. I wouldnt mind helping you with this entire exercise had you posted your answers but it appears by this you have not tried at all.

Im not wanting people to do the whole thing for me. There are questions that I have no idea about, cannot find in my book and cannot find a simplified answer for by googling. I was simply in need of help. I didnt expect to post this and get ridiculed and have people give me "THUMBS DOWN" responses.

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? Leveled line
2.   What is the threshold voltage?         .8 V
3.   How does the graph generated at the threshold voltage differ from the graphs generated at voltages below the threshold? They were Level

Activity 3:  Effect of Increases in Stimulus Intensity

1.   How did the increases in voltage affect the peaks in the tracings? In the beginning significantly once the voltage reached 10 the affect was minimal
2.   How did the increases in voltage affect the amount of active force generated by the muscle? 0.00 – 1.82 it increased the active force.
3.   What is the voltage beyond which there were no further increases in active force? Maximal voltage: 8.5  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? Yes be

Multiple Stimulus
Activity 4:  Treppe

1.   What do you observe? The Trace rise and fall, while the force in grams increased.

Activity 5:  Summation

1.   What is the active force of the contraction? 1.83 gms
2.   What is the active force now? 2.77 gms
3.   Was there any change in the force generated by the muscle? No
4.   Was there any change in the force generated by the muscle? Yes
5.   Why has the force changed?
6.   Do you see the same pattern of changes in the force generated? No
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? The line leveled out
2.   What is this condition called? Fatigue
3.   How does the trace at 130 stimuli/sec compare with the trace at 50 stimuli/sec?
4.   What is this condition called? Active force increased
5.   At what stimulus frequency is there no further increase in force? 146
6.   What is this stimulus frequency called? Tetanus

Activity 7:  Fatigue

1.   In fatigue, what happens to force production over time? Force produced is reduced, when the muscle is over-stretched or under-stretched it is weaker. Most muscles will produce max force at roughly 90 degrees.

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   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?  100             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?     100          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?    3.77     msec
2.   At what point in the trace does the muscle shorten? 40 msecs
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? No
5.   How does this trace differ from the trace you generated with the 0.5 gram weight attached?      Velocity and Active Force increased.
6.   Examine the plot data and your numerical data.  At what weight was the velocity of contraction the fastest?   2.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? There was no plateau on the trace.
8.   What kind of trace did you get? Up and down no leveling out.
9.   What was the force of the contraction?     .50    grams
10.   With the 1.0 gram weight, what kind of trace did you get?  What was the force of the contraction? Level Trace     1   grams
11.   With the 1.5 gram weight, what kind of trace did you get?  What was the force of the contraction? Level Trace     1.51   grams
12.   With the 2.0 gram weight, what kind of trace did you get?  What was the force of the contraction? Slight increase in the beginning then the trace leveled out        grams
13.   Describe your four tracings and explain what has happened in each of them. First three were level, the last being 2.0g had a slight increase in the beginning
14.   What muscle length(s) generated the fastest contraction velocity? 20.0g

Used this sight for help on my previous Lab assignments so I wanted to give back, I received a 98 out of 100 on this from my professor so it should be accurate.

physio ex 8.0
istonic contraction (review sheet Pg 29)
16.in activity 9, which weight resulted in the highest initial velocity of shortening?
17.explain the relationship between the amount fo resistance and the intial 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 sam number of repetitions with a 5-pound weight.

Thank You!

i am having a difficult time with number 10 and 11.

10. FOr Activity 6, explain how you were able to achieve smooth muscle 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.

Smooth contractions at a given force level are obtained by increasing the force of stimulation for a high force level or decreasing the force of stimulation for a low force level.

anybody know where i can get the physioex 8.0 A&P exercise 2 answers, must be "A&P"

Can anyone help me with these questions from the physio ex 8.0 lab, I just finished the stimulations and not entirly sure how to answer these 2 questions.

4.4. The graph shows a dip at muscle length = 90 mm. Why is this?




4.5. What is the key variable in an isometric contraction?