Ms. Kaminski's Science Site



Virtual Lab: Muscle Stimulation

1. Open the Virtual Lab entitled “Muscle Stimulation”. Please read the “Information” window that opens; click the “X” to close the window when you are finished. You can reopen this information in the future by clicking the “Information” button found at the bottom of the laboratory area.

2. The left side of the page contains background information and instructions in the “Question” area. On the bottom of the page are the following icons for your use: “Journal” (these are questions that may be answered/submitted to your instructor), “Calculator” (working calculator function), “Data Table” (where you may be submitting your collected data from the exercise), “Audio” (turns sound on/off) and “Print” (prints the screen).

3. Read the background information found under the “Question” area first, and then continue on to reading the procedure information posted there as well.

4. At this point, you are ready to begin the lab exercise. You will need to first open and/or print the “Post-Lab Quiz and Lab Report”, which can be found on the previous page. When you are ready, select the muscle type you would first like to test on the “Muscle” pull down menu. Remember to follow the directions given to you in the “Question” as well as in the “Post-Lab Quiz and Lab Report” areas, and refer back to your notes in the “Information” area if necessary.

5. Complete the exercise as directed, recording any data or information needed in your “Data Table” (icon on the bottom of the page) and/or your “Lab Report”.

6. When you are finished, please answer all of the questions found at the end of the “Post-Lab Quiz and Lab Report”.

Virtual Lab: Muscle Stimulation

Post-Lab Quiz and Lab Report

7. Please make sure you have read through all of the information in the “Question” and “Information” areas. If you come upon terms that are unfamiliar to you, please refer to your textbook for further explanation or search the word here:

8. In this exercise, you will use an oscilloscope to examine the effect of varying load (weight) on frog skeletal muscle action. To begin, click on the pull down menu of the “Muscle” button to select the type of muscle you would first like to test. Making sure that the oscilloscope is set to “0V”, click the “Apply Stimulus” button. As you do so, pay close attention to the trace readout on the screen; you are looking specifically for a spike in the straight line to be produced. If no spike is observed, use the upward pointing arrow on the oscilloscope to increase the voltage to the next highest level and then click “Apply Stimulus”. Keep repeating this procedure until you observe the production of a spike in the oscilloscope trace readout. At that point, note the voltage in the “0g” load weight in your “Data Table” and/or in Table I below.

NOTE: If no spike is observed, be sure to click “Apply Stimulus” at least 3 times to make sure the muscle received the stimulus properly.

9. When you are through, you will then need to repeat the above steps using the varying loads (weights). To do so, drag the 5g weight to the hook attached to the frog muscle and then proceed as you did to test the muscle action in step 2 above. When you are through testing the 5g weight, repeat these steps using each of the four remaining loads.

10. When you are completely finished testing all variables for the muscle type selected, you will need to repeat this procedure for ALL three remaining muscle types. Remember, you can always click the “Reset” button to clear your experiment and start fresh. Be sure to appropriately note all of your data in the “Data Table” or Table I below.

11. Please finish this exercise by opening the “Journal” link at the bottom of the page and answering the questions (also found below).

1. Contrast voluntary and involuntary muscles. Include what types of muscles are in each category and where these muscles are found.

2. What attaches muscle to bones?

3. What is the “all or none” law of muscle contraction?

4. How is the strength of the muscle contraction determined?

5. Define a muscle twitch:

6. Define a muscle’s “threshold of stimulation:”

7. Define the “point of muscle overload:”

Table I: Threshold Stimulus (V)

|Load |Lower Forelimb Muscle |Upper Forelimb Muscle |Calf Muscle |Thigh Muscle |

|0g | | | | |

|5g | | | | |

|10g | | | | |

|20g | | | | |

|40g | | | | |

|80g | | | | |

ANALYSIS:

1. Based on the results of your investigation, what conclusions can you draw about the relationship between a muscle's workload and its threshold of stimulation?

2. Why would a muscle's threshold of stimulation change as its Workload changes?

3. Which muscles were able to contract under the greatest loads? What does this suggest about the role these muscles play in frog movement?

4. Describe an experiment you might perform to determine which leg muscles of a frog are important for jumping long distances.

5. What are some advantages of performing this experiment in a simulated environment?

Post-laboratory Questions:

1. Smooth muscle:

a. Is voluntary

b. Is found in the heart

c. Is found in lining the intestines

d. All of the above

2. Skeletal muscle:

a. Is involuntary

b. Is made up of muscle fibers

c. Is attached to bone via ligaments

d. All of the above

3. In skeletal muscle:

a. The greater the number of muscle fibers responding to a stimulus, the greater the strength of the contraction

b. the fewer the number of muscle fibers responding to a stimulus, the greater the strength of the contraction

c. the actual number of muscle fibers responding to a stimulus has no effect on the strength of the contraction

4. An oscilloscope:

a. Provides stimulus to a tested muscle

b. Adds weight (load) to a tested muscle

c. Measures a twitch response of a tested muscle

d. A and C

e. All of the above

5. At the point of muscle overload:

a. Skeletal muscle contracts steadily (tetany)

b. Skeletal muscle contracts and relaxes repeatedly

c. Skeletal muscle does not contract at all

6. A skeletal muscle’s “threshold of stimulation”:

a. Is determined by the lowest voltage stimulus needed to elicit a muscle twitch

b. Varies with muscle type

c. Is not altered by the application of muscle load

d. B and C

7. In response to a stimulus, skeletal muscle fibers:

a. Always contract to 25% of their potential ability

b. Always contract to 50% of their potential ability

c. Always contract 100% of their potential ability

d. None of the above

8. Based upon your experimental data, which muscle type exhibited the lowest threshold of stimulation in all conditions tested?

a. Lower forelimb muscle

b. Upper forelimb muscle

c. Calf muscle

d. Thigh muscle

9. Based upon your experimental data, which muscle type(s) did not reach the point of muscle overload?

a. Lower forelimb muscle

b. Upper forelimb muscle

c. Calf muscle

d. Thigh muscle

10. Based upon your experimental data, which muscle tested appears most capable to provide the contraction strength needed for a frog to jump?

a. Lower forelimb muscle

b. Upper forelimb muscle

c. Calf muscle

d. Thigh muscle

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download