Skeletal Muscle - Lab report

Page 1 of 3 PC1001: Week 8 Skeletal Muscle Laboratory Marking Key Title: ( 1 mark ) Aim: Make sure you mention all components of the laboratory . ( 2 marks ) Introduction: (2 4 marks total ) Your introduction should des cribe the physiological pr operties of skeletal muscle, e xcitation – co ntractio n ( E C) coupling and sliding filament theory. D efine the “all or n one” law gove rning a muscle t w itch. Define: twi tch, summation, t etanus , and fatigue . Cite referenc es in text using the Ha rvard ( A uthor ‐date) or AMA/ Vancouver (superscript number) referencing s y stem ( check JCU Library Libguides here ( http://libguides.jcu.edu.au/referencing ) if unsure ). W rite a sentence or 2 on these topics (figures / tables are also allowed) :

Describe Physiological properties of skeletal muscles: (4 marks) Describe EC coupling: (4 marks) Describe Sliding filament theory: (4 marks) Define all or none law: (2marks) Define twitch: ( 2 marks) Define summation : wave and recruitment : (4 marks) Define tetanus: ( 2 marks) Define Fatigue: (2 marks) Material and Methods : ( 2 marks) Quickly summarise the experimental set up here (it is OK to quote P C1001 Week 8 L aboratory Notes), a picture of the set up is also permitted .

Results: (40 Marks total, 5 exercises x 8 marks ) Attach a copy of the completed Toad Skeletal Muscle Data Notebook at the end of this report and label it ‘Appendix 1’ Graph marking: 0.5 = correct graph type (bar, line etc) 0.5 = correct data plotted 2 = data plot on correct axis, axis labeled, correct units 1 = c omplete figure legend Table marking: may appear just in the appendix rather than a repeated table 1. 5 = Complete t able header (above table) 0.5 – Correct data ( with units) Text: 2 mark s for appropriate text describing each exercise, must refer to Figure / T able.

EXERCISE 1: The effect of stimulus intensity on contraction force Draw a line graph of contraction force (Y) versus stimulus intensity (X), label it ‘Figure 1: Contraction force versus stimulus intensity’ Use the data from Table 1 of the Data Notebook. In words, describe what is happening to contraction force as stimulus voltage increases . Page 2 of 3 Table 1 may be here or in appendix 1 .

E XERCISE 2: The effect of preload on muscle contraction force Draw a line graph of net twitch force (Y) versus preload force (X), label it ‘Figure 2: Net twitch force versus preload” Use the data from Table 3 of the Data Notebook. Can be a line graph or a scatter plot In words, describe what is happening to net twitch force as prelo ad increases Table 3 may be here or in appendix 1 .

EXERCISE 3: The effect of stimulus frequency on contraction force Draw a bar chart of force of first and second peak (Y) versus stimulus frequency (X), label it ‘Figure 3: Effect of stimulus frequency on force of two consecutive contractions ” Use the data from Table 4 of the Data Notebook. Cannot be a line graph In words, describe what is happening to force of the second peak as stimulus frequency increases .

Table 4 may be here or in appendix 1 .

E XERCISE 4: Tetanus Draw a line graph of maximum force (Y) versus stimulus interval (X), label it ‘Figure 4: Maximum force versus stimulus frequency” Use the data from Table 5 of the Data Notebook. In words, describe what is happening to force of the second peak as stimulus frequency increases .

Table 5 may be here or in appendix 1 .

E XERCISE 5: Muscle fatigue Draw a line graph of contraction force (Y) versus time since stimulation (X), label it ‘Figure 5: Contraction force versus time since stimulation” Use the data from Table 6 of the Data Notebook. In words, describe what is happening to force of contraction as the time since stimulation increases .

Table 6 may be here or in appendix 1. Discussion: ( 24 marks total) Answers the following questions in your discussion (questions (or #) can be repeated, or paragraph breaks use to define questions . Refer to figures and tables rather than inserting in discussion text. Page 3 of 3 1. Describe why you observe a graded response to increasing stimulus intensity in lig ht of the “all or none” law governing muscle contraction. 5 marks 2. Explain why muscle contracts more forcefully when stretched (ie when preload is increased ) 5 marks 3. Mechanistically, what happens to the muscle at the highest preload forces? 4 marks 4. When the muscle was stimulated repeatedly, what happened the force of contraction? Explain the mechanism behind this phenomenon. 5 marks 5 . Explain why muscle fatigue occurs. How long was your preparation able to maintain a maximal contraction? Would your results have differed if you were measuring from smooth muscle tissue? Why? What approach do working muscles use to delay the onset of fatigue? 5 marks Conclusion: (2 marks) Make concluding statement of approximately 150 -200 words to summarise the outcomes of laboratory. References: ( 5 marks) Include 5 -10 references of at least 3 different types (textbook s, journal /review articles, reputable websites) to support your report . 1 - Consistent formatting 3 - Appropriate references (no generic web sites, eg: Wikipedia) all references referred to, all included in list .

1 - Appropriate in text referencing Any plagiarized section or report receives mark of zero Summary of Marking allocation for this laboratory report : Title 1 Aim 2 Introduction 24 Materials and Methods 2 Results 40 Discussion 24 Conclusion 2 References 5 Total 100 (10% Final Assessment)