Differences Between Smooth and Skeletal Muscle Contraction
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Differences Between Smooth and Skeletal Muscle Contraction

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Questions and Answers

Which type of muscle contraction is regulated by thick filaments?

  • Visceral muscle contraction
  • Striated muscle contraction
  • Smooth muscle contraction (correct)
  • Skeletal muscle contraction

    • What type of smooth muscle is characterized by having extensive intercellular electrical communication?

  • Multi-unit smooth muscle
  • Tonic smooth muscle
  • Syncytial smooth muscle (correct)
  • Single-unit smooth muscle

    • In smooth muscles, what controls the contractile process by causing changes in intracellular calcium concentration?

  • Production of second messengers (correct)
  • Activation of neuromuscular junctions
  • Action potentials
  • Opening of membrane channels

    • Which type of smooth muscle operates with each fiber being innervated by a single nerve ending, similar to skeletal muscle fibers?

    <p>Multi-unit smooth muscle</p> Signup and view all the answers

    What is the normal range of intracellular potential in smooth muscle at rest?

    <p>$-50$ to $-60$ millivolts</p> Signup and view all the answers

    What is the key characteristic of multi-unit smooth muscle fibers?

    <p>Independent contraction of each fiber</p> Signup and view all the answers

    In which type of smooth muscle do action potentials occur similarly to skeletal muscle?

    <p>Unitary smooth muscle</p> Signup and view all the answers

    Which component is absent in multi-unit smooth muscle fibers compared to skeletal muscle fibers?

    <p>Neuromuscular junction</p> Signup and view all the answers

    Which type of smooth muscle contraction responds to electrical and hormonal stimulation?

    <p>Single/multi-unit muscle contraction</p> Signup and view all the answers

    What type of junctions join the cell membranes of syncytial smooth muscle fibers?

    <p>Gap junctions</p> Signup and view all the answers

    What is the main mechanism by which chemical factors control the function of smooth muscle cells?

    <p>Production of second messengers</p> Signup and view all the answers

    Which characteristic distinguishes tonic smooth muscle from other types of smooth muscle?

    <p>Each fiber operates independently</p> Signup and view all the answers

    What is a major difference between the physical organization of smooth muscle and skeletal muscle?

    <p>Absence of sarcoplasmic reticulum in smooth muscle</p> Signup and view all the answers

    How is smooth muscle contraction dependent on calcium ions?

    <p>Extracellular calcium ion concentration</p> Signup and view all the answers

    What type of pump is required for smooth muscle relaxation?

    <p>Calcium pump</p> Signup and view all the answers

    What is the duration of contraction like in smooth muscle compared to skeletal muscle?

    <p>Shorter in smooth muscle</p> Signup and view all the answers

    What controls the contractile process in smooth muscle?

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

    Which structure is not well-developed in smooth muscle compared to skeletal muscle?

    <p>T-tubules</p> Signup and view all the answers

    What is the primary step in the regulation of smooth muscle contraction?

    <p>Phosphorylation of the regulatory light chains of the myosin molecule</p> Signup and view all the answers

    Which factor causes smooth muscle relaxation and vasodilation due to lack of oxygen in local tissues?

    <p>Adenosine buildup</p> Signup and view all the answers

    Which hormone does not affect smooth muscle contraction according to the text?

    <p>Aldosterone</p> Signup and view all the answers

    What is the rhythmic potential change called that results from the periodic variation of the resting potential in smooth muscles?

    <p>Slow wave</p> Signup and view all the answers

    Which ion plays a role in smooth muscle relaxation based on the text?

    <p>Increased potassium ions</p> Signup and view all the answers

    What must occur for myosin to interact with actin during smooth muscle contraction?

    <p>Phosphorylation of myosin light chains</p> Signup and view all the answers

    What is the structural difference in actin and myosin filament arrangement between smooth muscle and skeletal muscle?

    <p>In smooth muscle, actin filaments are attached to dense bodies, while in skeletal muscle, they are arranged in a striated pattern with myosin filaments.</p> Signup and view all the answers

    How are the dense bodies in smooth muscle related to Z lines in skeletal muscle?

    <p>Dense bodies in smooth muscle are the functional equivalents of Z lines in skeletal muscle.</p> Signup and view all the answers

    What type of junctions provide low-resistance pathways for action potentials to propagate between smooth muscle cells?

    <p>Gap junctions</p> Signup and view all the answers

    Which molecule activates the contractile process in smooth muscle cells?

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

    How is the control of contraction different between smooth muscle and skeletal muscle?

    <p>Smooth muscle lacks the troponin complex that controls contraction in skeletal muscle.</p> Signup and view all the answers

    What provides the energy for contraction in smooth muscle cells?

    <p>Adenosine triphosphate (ATP)</p> Signup and view all the answers

    Study Notes

    • Smooth muscle fibers can be arranged in sheets/bundles, with cell membranes adhering to each other to transmit force.
    • Unitary smooth muscle has extensive intercellular electrical communication and is also known as syncytial smooth muscle.
    • Multi-unit smooth muscle is composed of separate fibers that operate independently, each innervated by a single nerve ending.
    • Multi-unit smooth muscle lacks T-tubules, troponin complex, and neuromuscular junctions found in skeletal muscle.
    • Smooth muscle contraction is activated by calcium ions, with differences in excitation-contraction coupling compared to skeletal muscle.
    • Smooth muscle contraction is dependent on extracellular calcium ion concentration, requiring a calcium pump for relaxation.
    • Factors like lack of oxygen, excess carbon dioxide, and various hormones can affect smooth muscle contraction.

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    Related Documents

    5.Smooth Muscle Physiology.pptx

    Description

    Explore the major differences between the physical organization of smooth muscle and skeletal muscle, as well as variations in excitation-contraction coupling, calcium ion control, duration of contraction, and energy requirements in the contraction process.

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