1. The main sources of muscle fibers are:
- Skeletal muscle
- Cardiac muscle
- Smooth muscle
2. What occurs when a muscle contracts? (Select all that apply)
- Actin and myosin filaments slide past each other
- Sarcomere shortens
- Z-lines move closer together
- Muscle fiber generates tension
3. Which structure is responsible for storing calcium ions?
- Sarcoplasmic reticulum
4. What triggers the release of calcium from the sarcoplasmic reticulum?
- Action potential traveling along the T-tubule
5. Calcium binds to which protein to initiate contraction?
- Troponin
6. What is the role of ATP in muscle contraction?
- Provides energy for cross-bridge cycling
- Detaches myosin from actin
- Powers the calcium pump to return calcium to the sarcoplasmic reticulum
7. Place the following events in order during muscle contraction:
1. Action potential arrives at neuromuscular junction
2. Acetylcholine released, binds to receptors on motor end plate
3. Action potential propagates along sarcolemma and T-tubules
4. Calcium released from sarcoplasmic reticulum
5. Calcium binds to troponin, exposing myosin-binding sites on actin
6. Myosin heads bind to actin, forming cross-bridges
7. Power stroke occurs, sliding filaments
8. ATP binds to myosin, causing detachment
9. ATP hydrolyzed, re-cocking myosin head
10. Calcium pumped back into sarcoplasmic reticulum, muscle relaxes
8. True or False: Muscle contraction requires oxygen.
- False (Anaerobic glycolysis can support short-term contraction)
9. What is the function of tropomyosin?
- Blocks myosin-binding sites on actin in relaxed state
10. Which of the following is NOT a type of muscle tissue?
- Epithelial muscle (Correct answer: Epithelial tissue is not muscle tissue)
Parent Tip: Review the logic above to help your child master the concept of sliding filament theory worksheet.
