https://www.youtube.com/watch?v=p73VE3GSdZg

in the first 5 minutes of the video, might need to pause :)

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

2. What attaches muscles 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" and the "point of muscle overload".

Next Scientist Cindy will a muscle stimulation on the frog muscles, pay attention to what she is doing and try to relate what you learned in the 6 questions above to answer the 4 questions below:

7. Based on the results of Scientist Cindy's investigation, what inferences can you draw about the relationship between a muscle's workload and its threshold of stimulation?

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

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

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