Concept Check


  1. Why is elasticity an important quality of muscle tissue?
  2. Describe how tendons facilitate body movement.
  3. What causes the striated appearance of skeletal muscle tissue?
  4. How would muscle contractions be affected if ATP was completely depleted in a muscle fiber?
  5. Why does a motor unit of the eye have few muscle fibers compared to a motor unit of the leg?
  6. How are cardiac muscle cells similar to and different from skeletal muscle cells?
  7. Watch this videoto learn more about macro- and microstructures of skeletal muscles. (a) What are the names of the “junction points” between sarcomeres? (b) What are the names of the “subunits” within the myofibrils that run the length of skeletal muscle fibers? (c) What is the “double strand of pearls” described in the video? (d) What gives a skeletal muscle fiber its striated appearance?
  8. Every skeletal muscle fiber is supplied by a motor neuron at the NMJ. Watch this videoto learn more about what happens at the neuromuscular junction. (a) What is the definition of a motor unit? (b) What is the structural and functional difference between a large motor unit and a small motor unit? Can you give an example of each? (c) Why is the neurotransmitter acetylcholine degraded after binding to its receptor?
  9. The release of calcium ions initiates muscle contractions. Watch this videoto learn more about the role of calcium. (a) What are “T-tubules” and what is their role? (b) Please also describe how actin-binding sites are made available for cross-bridging with myosin heads during contraction.
  10. Movements of the body occur at joints. Describe how muscles are arranged around the joints of the body.
  11. Which muscles form the hamstrings? How do they function together?
  12. Which muscles form the quadriceps? How do they function together?

The muscular system: Skeletal muscle of the muscular system is closely associated with the skeletal system and acts to maintain posture and control voluntary movement.