Chapter 12 Clicker Qs

Which of the following characteristics differentiates skeletal muscle from both cardiac and smooth muscle?

a. multinucleated fibers
b. appears striated under the microscope
c. has the ability to generate force
d. movement is controlled by a somatic motor neuron
e. Both A and D
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Which of the following characteristics differentiates skeletal muscle from both cardiac and smooth muscle?

a. multinucleated fibers
b. appears striated under the microscope
c. has the ability to generate force
d. movement is controlled by a somatic motor neuron
e. Both A and D
e. Both A and D
During exercise, blood flow shifts from the GI tract to skeletal muscle as a result of increased oxygen demand. Which type of muscle is primarily responsible for redirecting blood flow?

a. smooth
b. skeletal
c. cardiac
d. It is not muscle that is redirecting blood flow.
a. smooth
Which of the following allows action potentials to move rapidly from the cell surface into the interior?

a. terminal cisternae
b. fascicles
c. T-tubules
d. crossbridges
e. sarcoplasmic reticulum
c. T-tubules
Quadriceps are the large muscles located on the front of the thigh. They originate up in the hip and insert below the knee. Which of the following is/are correct?

a. Contraction of the quadriceps moves the tibia.
b. Quadriceps are responsible for knee flexion.
c. Standing up from sitting in a chair will cause recruitment of the quadriceps.
d. Hamstrings located on the back of the thigh are antagonist.
e. A, B, and D
e. A, B, and D
Which of these statements about sarcomere shortening is FALSE?

a. The thick and thin filaments slide past each other.
b. The length of the A band remains constant. c. The length of the I band remains constant. d. The H zone almost disappears.
c. The length of the I band remains constant.
Which of the following is a potential energy source for an athlete sprinting the 40-yard dash?

a. myoglobin
b. phosphocreatine
c. creatine kinase
d. ryanodine receptors
e. None of the above
b. phosphocreatine
Why does rigor mortis occur after death?

a. There is no ATP available to bind to myosin. b. Body temperature drops.
c. The connective tissue surrounding muscle fascicles starts to harden.
d. Myosin is tightly bound to actin.
e. Both A and D
e. Both A and D
Which of these statements about smooth muscle contraction is FALSE?

a. It uses actin and myosin cross-bridges to create force.
b. It can occur without a change in membrane potential.
c. Ca2+ initiates contraction.
d. Troponin plays the same role as in skeletal muscle.
d. Troponin plays the same role as in skeletal muscle.
In hyperkalemia, the resting membrane potential of a muscle fiber is _______ negative and _______ likely to depolarize.

a. less; more
b. less; less
c. more; more
d. more; less
a. less; more
Which of the following is NOT true regarding innervation of skeletal muscle?

a. Cell body of somatic motor neurons are contained within the CNS and axons extend out to skeletal muscle fibers.
b. A motor unit is a single somatic motor neuron and all of the muscle fibers it innervates.
c. Each motor unit contracts in all at once.
d. Multiple motor units innervating a skeletal muscle also contract all at once.
d. Multiple motor units innervating a skeletal muscle also contract all at once.
Skeletal muscle contraction starts when the muscle fiber depolarizes due to the release of calcium into the cytoplasm. a. True b. Falseb. FalseAcetylcholine receptor-channels allow the passage of _______ when open. a. Na+ b. K+ c. both Na+ and K+ d. Cle. Ca2+c. both Na+ and K+Which of the following phases of a muscle twitch requires ATP? a. latent period b. contraction period c. relaxation period d. B and C e. A, B, and Cd. B and CDrug "X" inhibits acetylcholinesterase action within the neuromuscular junction. What would drug "X" do to the membrane potential of the muscle fiber? a. It would remain depolarized. b. It would repolarize more quickly than normal. c. It would hyperpolarize. d. Drug "X" would have no effect on the membrane potential.a. It would remain depolarized.Which of the following is true for a somatic motor neuron action potential but not a skeletal muscle fiber action potential? a. occurs as a result of an inward Na+ current b. occurs as a result of an outward K+ current c. leads to the release of ACh d. leads to the release of Ca2+ from the sarcoplasmic reticulumc. leads to the release of AChIn smooth muscle, the Ca2+ for contraction comes from a. mitochondria. b. extracellular fluid. c. sarcoplasmic reticulum. d. B and C e. A, B, and Cd. B and CWhich of the following is NOT thought to play a role in muscle fatigue during normal exercise? a. muscle glycogen depletion b. decreased ACh release c. increased Pi d. locally elevated ECF K+ e. All of above play a role in muscle fatigue.b. decreased ACh releaseProlonged inactivity, such as a limb immobilized in a cast, can cause which of the following physiological consequences? a. reduced blood supply to the muscle b. somatic motor neuron dysfunction c. reduction in the size of muscle fibers d. A and C e. All of the aboved. A and CHow do the skeletal muscle fibers in the legs of a marathon runner differ from those of an individual that runs the 100-meter dash? a. longer and thinner muscle fibers b. mostly slow-oxidative fibers c. mitochondrial content will be higher d. less fatigable e. All of the abovee. All of the aboveWhen a skeletal muscle lengthens, its sarcomeres a. shorten. b. stay the same length. c. lengthen.c. lengthen.A muscle develops its maximal force at its a. shortest length. b. intermediate length (Resting muscle length). c. maximal length.b. intermediate length (Resting muscle length).A skeletal muscle contracts most quickly against a(n) a. minimal load. b. intermediate load. c. maximum load.a. minimal load.