Smooth Muscle Study Questions Bank

11 Questions | Total Attempts: 3179

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Smooth Muscle Study Questions Bank - Quiz

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Questions and Answers
  • 1. 
     Smooth muscle cells are initiated to contract by all of the following ways except which?
    • A. 

      Depolarization from a neighboring cell spread through connexon channels

    • B. 

      Norepinephrine binding to α1-adrenergic receptors

    • C. 

      Acetylcholine binding to nicotinic acetylcholine receptors

    • D. 

      The movement of a bolus of food through the small intestine

  • 2. 
    Which of the following muscle proteins plays a critical role in contraction of both smooth and striated muscle?
    • A. 

      Calmodulin

    • B. 

      Troponin

    • C. 

      Tropomyosin

    • D. 

      Actin

    • E. 

      Myosin light chains

  • 3. 
    During the process of excitation-contraction coupling in smooth muscle, intracellular [Ca2+] is increased through all of the following methods except which?
    • A. 

      Ca2+ influx from extracellular stores through voltage-activated Ca2+ channels

    • B. 

      Ca2+ influx from the sarcoplasmic reticulum through IP3 receptors

    • C. 

      Ca2+ influx from extracellular stores through ryanodine receptors

    • D. 

      Ca2+ influx from extracellular stores through ligand-gated Ca2+ channels

  • 4. 
    Which of the following temporal sequences is correct for excitation-contraction coupling in smooth muscle?
    • A. 

      Ca2+ influx through IP3 receptors, cross-bridge cycling, Ca-calmodulin activation of MLCK, Ca2+ removal from SR by SERCA, PMCA, and Na/Ca exchanger

    • B. 

      Ca2+ influx through RyR in the SR, Ca2+ removal from SR by SERCA, PMCA, and Na/Ca exchanger, Ca-calmodulin activation of MLCK, cross-bridge cycling

    • C. 

      Ca2+ influx through L-type Ca2+ channels, Ca2+ activated Ca2+ release from RyR in the SR, Ca-calmodulin activation of MLCK, cross-bridge cycling, Ca2+ removal from SR by SERCA, PMCA, and Na/Ca exchanger

    • D. 

      Ca2+ influx through store-operated Ca2+ sensitive channels, cross-bridge cycling, Ca2+ removal from SR by SERCA, PMCA, and Na/Ca exchanger, Ca-calmodulin activation of MLCK

  • 5. 
    When comparing the contractile responses in smooth and skeletal muscle, which of the following is most different?
    • A. 

      The source of activator calcium

    • B. 

      The role of calcium in initiating contraction

    • C. 

      The mechanism of force generation

    • D. 

      The source of energy used during contraction

    • E. 

      The nature of the contractile proteins

  • 6. 
    In excitation-contraction of smooth muscle, calcium binds to what protein after influx into the cytoplasm?
    • A. 

      Calmodulin

    • B. 

      Myosin light chains

    • C. 

      Troponin

    • D. 

      Tropomyosin

    • E. 

      Protein kinase A

  • 7. 
    Which of the following enzymes is responsible for dephosphorylating myosin light chains, thereby causing smooth muscle relaxation?
    • A. 

      Calmodulin

    • B. 

      Protein kinase A

    • C. 

      Myosin light chain kinase

    • D. 

      Myosin light chain phosphatase

    • E. 

      Phospholipase C

    • F. 

      Actomyosin ATPase

  • 8. 
    The role of myosin light-chain protein in smooth muscle is what?
    • A. 

      Bind to calcium ions to initiate excitation-contraction coupling

    • B. 

      Phosphorylate cross-bridges, thus driving them to bind with the thin filament

    • C. 

      Split ATP to provide the energy for the power stroke of the cross-bridge cycle

    • D. 

      Dephosphorylate myosin light-chains of the cross-bridge, thus relaxing the muscle

    • E. 

      Pump calcium from the cytosol back into the sarcoplasmic reticulum

  • 9. 
    Single-unit smooth muscle differs from multiunit smooth muscles how?
    • A. 

      Single-unit muscle contraction speed is slow, while multiunit is fast

    • B. 

      Single-unit muscle has T-tubules, while multiunit does not

    • C. 

      Single-unit muscles are not innervated by autonomic nerves

    • D. 

      Single-unit muscle produces action potentials spontaneously that spreads to neighboring cells, while multiunit does not

  • 10. 
    Which of the following enzymes is responsible for phosphorylating myosin light chains in order to activate smooth muscle contraction?
    • A. 

      Calmodulin

    • B. 

      Protein kinase A

    • C. 

      Myosin light chain kinase

    • D. 

      Phospholipase C

    • E. 

      Actomyosin ATPase

  • 11. 
    Which characteristic or component is shared by skeletal muscle and smooth muscle?
    • A. 

      Thick and thin filaments arranged in sarcomeres

    • B. 

      Troponin

    • C. 

      Elevation of intracellular [Ca2+] for excitation-contraction coupling

    • D. 

      Spontaneous depolarization of the membrane potential

    • E. 

      High degree of electrical coupling between cells