Muscle physiology 2
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Questions and Answers

What structural component of smooth muscle provides structural stability?

  • Troponin
  • Intermediate filaments (correct)
  • Thick filament
  • Actin

    • What is the role of myosin light chain in smooth muscle contraction?

  • Binds to actin when phosphorylated (correct)
  • Activates calmodulin
  • Releases calcium ions
  • Facilitates ATP hydrolysis

    • Which type of smooth muscle is characterized as neurogenic?

  • Multiunit (correct)
  • Single unit
  • Phasic
  • Non-phasic

    • What happens to the thin filaments during smooth muscle contraction?

    <p>Pass in opposite directions along thick filaments (D)</p> Signup and view all the answers

    Which molecule binds with calmodulin to initiate the cross-bridge cycle in smooth muscle contraction?

    <p>Calcium ions (B)</p> Signup and view all the answers

    What replaces Z lines in smooth muscle cells since they lack sarcomeres?

    <p>'Dense bodies' (D)</p> Signup and view all the answers

    Which type of muscle has filaments that send signals in opposite directions rather than in the middle?

    <p>Smooth muscle (C)</p> Signup and view all the answers

    What is the primary role of myosin light chain kinase in smooth muscle contraction?

    <p>Add a phosphate group to myosin light chain (A)</p> Signup and view all the answers

    What is the structural significance of the dense bodies in smooth muscle?

    <p>Structurally stabilizes and holds together the filaments in a criss-cross pattern.</p> Signup and view all the answers

    Explain the role of myosin light chain phosphorylation in smooth muscle contraction.

    <p>Phosphorylation is necessary for myosin head to bind to actin and initiate the cross-bridge cycle.</p> Signup and view all the answers

    What is the function of calmodulin in smooth muscle contraction?

    <p>Calmodulin binds with Ca2+ and activates myosin light chain kinase.</p> Signup and view all the answers

    Describe the arrangement of thick and thin filaments in smooth muscle cells during contraction.

    <p>Thin filaments pass in opposite directions along thick filaments.</p> Signup and view all the answers

    What is the role of intermediate filaments in smooth muscle cells?

    <p>Provide structural stability.</p> Signup and view all the answers

    How does multiunit smooth muscle differ from single unit smooth muscle?

    <p>Multiunit smooth muscle is neurogenic and phasic.</p> Signup and view all the answers

    Explain the significance of myosin light chain kinase in the cross-bridge cycle.

    <p>Myosin light chain kinase phosphorylates myosin light chain, allowing for cross-bridge formation.</p> Signup and view all the answers

    How do the thick filaments in smooth muscle differ from those in skeletal muscle?

    <p>Thick filaments in smooth muscle have more heads available for binding and send filaments in opposite directions.</p> Signup and view all the answers

    Smooth muscle cells have sarcomeres similar to skeletal muscles.

    <p>False (B)</p> Signup and view all the answers

    Calmodulin activates myosin light chain kinase by binding to it.

    <p>False (B)</p> Signup and view all the answers

    Multiunit smooth muscle is referred to as phasic and originates from neural stimulation.

    <p>True (A)</p> Signup and view all the answers

    The myosin light chain must be dephosphorylated for the myosin head to bind to actin in smooth muscle contraction.

    <p>False (B)</p> Signup and view all the answers

    Thin filaments in smooth muscle cells pass in the same direction along the thick filaments during contraction.

    <p>False (B)</p> Signup and view all the answers

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