9 Review

• Active sites on actin become available for binding when... calcium binds to troponin
• The function of a neuromuscular junction is to... facilitate chemical communication between the neuron and the muscle fiber
• The direct energy supply for skeletal muscle production is... ATP
• Another name for a muscle that is a prime mover is... agonist
• Each of the following changes in skeletal muscles is a consequence of aging except... muscle fibers increase glycogen reserves
• Interactions between actin and myosin filaments of sarcomere are responsible for... muscle contraction
• Theory that explains muscle contraction is known as... sliding filament theory
• The bundle of collagen fibers at the end of a skeletal muscle that attaches the muscle to bone is called... tendon
• To lessen the rate at which muscles fatigue during contraction, motor units are activated... on a rotating basis
• Ability to recover from injuries in older folk decreases because... number of myosatellite cells decreases with age AND fibrous tissue in muscle increases
• In which the ratio of motor neurons to muscle fibers the greatest?... Muscles that control the eye
• A way to warm up is exercise. What is the mechanism of this warming?... Muscle contraction uses ATP, generating heat
• Summarize the sequence of events that occurs at neuromuscular junction.

  Action potential arrives at axon terminal of neuromuscular synapse causing release of acetylcholine into the synaptic cleft, which then binds to receptors on sarcolemma. Change causes electrical signals to sweep over sarcolemma surface.
• A motor unit from a skeletal muscle contains 1500 muscle fibers. Would this muscle be involved in fine, delicate movements or powerful gross movements? Explain.


  Powerful gross movements. The more fibers there are, the more powerful it is with less fine control.
• What is the role of the zone of overlap in producing tension in a skeletal muscle?

  Thin filaments pass between thick filaments, forming cross-bridges so contraction occurs and tension is generated.
• Anatomy take up weightlifting and bodybuilding. Months later there is increased muscle mass, lean body weight, greater muscular strength. What anatomical mechanism is responsible for these changes?

  Anaerobic endurance. Repetative exercise allows fast fibers to develop further, increasing the size and strength.
• Within a decade or two, leg muscle biopsies are done on track athletes to see if they are better suited for sprints or long distance. What anatomical fact is the basis of this practice?

  Determining percentage of slow and fast muscle fibers. An athlete with more white muscle might be better at sprinting and an athlete with more red muscle might be better at long distance.