The Muscle System
Muscle Cells and Muscle Contraction Web Activity
In this activity you will explore both the structure (anatomy) and function (physiology) of skeletal muscle. Skeletal muscles work by pulling on bones. In order to pull on the bones the muscle length must shorten. This is a characteristic of muscle tissue known as contractility. The proposed mechanism for this contraction is called the sliding filament theory. Muscle cells (aka myofibers or muscle fibers) are made up of bundles of filaments called myofibrils. The filaments contained within these fibrils are made of protein. There are 2 main protein filaments you need to know. Actin is the protein that composes the thin filaments while myosin is the protein that composes the thick filaments. Additional proteins found in the myofibrils include tropomyosin, troponin and titin.
In order to understand the function of the skeletal muscle, you must first explore its anatomy and the structures that make up each cell.
You can get to the websites by going to my website, opening the Anatomy and Physiology home page, then find the muscle system web quest. The first site you need to visit is the Thomson Brooks/Cole Muscle Contraction Animation. Simply click on the link below.
When the page opens, there will be a short introduction with the objectives of the animation. Move to the next slide by clicking the arrow on the lower right corner. Use the information in the animation to answer these questions on a separate sheet of paper.
1. What is there a diagram of on the first slide? (give 3 names for it)
2. Copy the description of a muscle cell that appears in the right column.
3. What are myofibrils and how big are they?
4. Where are the sarcomeres located?
5. What is the sarcolemma?
6.What are transverse tubules-tubules?
7. How are the nerve impulses for contraction transmitted?
8. Where in the myofiber are mitochondria and nuclei located?
9. Drag the labels to the correct spot on the diagram – you have to complete this before you move on.
10. What are the bands that mark the sarcomere’s borders know as?
11. What are the lightest and least dense structures of a sarcomere?
12. What are the 3 proteins found in thin filaments?
13. Drag the labels to the correct part of the sarcomere – you must complete this to move on.
14. Draw a relaxed sarcomere
15. Draw a contracted sarcomere
16. Describe what happens to the H-zone and the I-band during contraction.
17. What happens in the sliding filament theory of contraction (copy it from the right column).
18. What is a cross bridge?
19. What causes the contraction of a sarcomere?
20. Why do the thin filaments not completely overlap the thick filaments?
21. What must the sarcomere do to relax?
22. What is titin and what does it do?
23. What drives a muscle contraction?
24. Where within the myofiber are calcium ions stored?
25. What stimulates the release of calcium?
26. To what does the calcium ion bind?
27. What happens to ADP during a “power stroke”?
28. What causes the release of myosin from the actin?
29. List the events of muscle contraction in order – you must complete this step to move on – copy the steps on your paper.
Now, go to the next website you can access it off the anatomy and physiology page on my website or the address is:
Click “simple quiz” and answer questions 1-14 and leave the rest unanswered. Scroll to the bottom of the page and submit answers. On your result page there is a section to e-mail your score. Put your name (first and last) in the “my name” box, your class period in the “section ID” box and MY e-mail address () in the “me” box…you do not need to fill in any other e-mail addresses.
30. Write how many questions you got right out of 14.