Sarco- What? Sarcomere! Student Activity Page How do skeletal muscles work? What triggers muscle contraction? How do muscles use the energy available in cells? You will soon be able to answer these questions and others, while applying what you have already learned about cellular functions. Your mission is to learn about skeletal muscle contraction on a cellular and molecular level, create a labeled diagram of a sarcomere, the functional unit of skeletal muscle, and explain how skeletal muscle functions. Your project has the following components: 1. Make a labeled diagram of a sarcomere, labeling and briefly describing the terms underlined in the word list below (note that adding 3 more terms makes you eligible for an exemplary score in this component): 1. muscle action potential 2. sarcomere 3. sarcoplasmic reticulum 4. Ca2+ 5. myosin (thick filament) 6. actin (thin filament) 7. A Band 8. I Band 9. H Zone 10. Z Line or Z Disc 11. cross-bridges (myosin heads) 12. troponin 13. tropomyosin 14. power stroke 15. sliding filament mechanism 2. Write an explanation using numbered steps (in your own words!) to describe what occurs in skeletal muscle contraction and relaxation, starting with the receipt of the neurotransmitter message in the sarcolemma and ending with the reabsorption of Ca2+ by the SR. Use ALL the terms listed above. Underline and number each term the first time it is used. Use additional terms (such as ACh, AchE, sarcolemma, t-tubules or others) as needed to explain the processes. 3. When you and your partner have finished making your diagram, each team member will individually explain the diagram to your teacher, describing its parts and the mechanism of the sliding filament model. You should use all of the terms listed above in your explanation. 4. Reflect on two aspects of this activity and write your thoughts concerning: a. what you learned about muscle anatomy and physiology in this activity; and b. how you can use the information from this activity.