Review Questions from Skeletal Muscle Lecture

Question 1: What tissues from part of a muscle (organ)? List 3 board functions of skeletal muscle. Describe the anatomical hierarchy of a muscle organ using these: organ, fascicle, 1 cell or myocyte = 1 muscle fiber, sarcomere, myofilaments.

2. Describe the roles of the connectives in a muscle (organ). What produces passive tension when a muscle is stretched? Predict what might affect the elasticity of different skeletal muscles or elasticity between different individuals.

3. Describe the development of muscle fibers from myoblast stem cells. Graph the proliferation of myofibers & myoblast on the Y-axis with age on the X-axis.

4. Describe the organization or location of the nuclei, myofibrils, sarcoplasmic reticulum and mitochondria within a myocyte (1 muscle cell).

5. Draw a sarcomere showing thick and thin filaments, & the z-line. How does a sarcomere shorten during a contraction? What limits sarcomere shortening? Graph the active tension curve of a muscle with resting length on the X-axis; explain why active tension varies at different sarcomere lengths.

6. What neurotransmitter is released by excited motor neurons at a neuromuscular junction for skeletal muscle? What role do T-tubules play in the excitation of the sarcoplasmic reticulum in a muscle cell?

7. Explain the importance of both channel-mediated diffusion out of the SR (into cytoplasm) & active transport of Ca²⁺ back into the sarcoplasmic reticulum.

8. Describe the major steps involved in a muscle contraction with regards to actin, myosin, activation sites, Ca²⁺ and energy (ATP → ADP)