Muscle Tissue Anatomy and Function
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Questions and Answers

What is the function of the sarcoplasmic reticulum in muscle cells?

  • Acts as the contractile protein
  • Maintains the structural integrity of myofibrils
  • Conducts electrical impulses
  • Stores and releases calcium ions (correct)
  • What type of protein is titin classified as?

  • Contractile protein
  • Enzymatic protein
  • Structural protein (correct)
  • Regulatory protein
  • How are thin filaments structured within skeletal muscle fibers?

  • Made primarily of titin
  • Composed of myosin only
  • Incorporate actin, tropomyosin, and troponin (correct)
  • Form a lattice around thick filaments
  • What is the role of Z discs in a muscle fiber?

    <p>Anchor thin filaments and stabilize myofibrils</p> Signup and view all the answers

    What distinguishes the I band in a sarcomere?

    <p>Contains only thin filaments</p> Signup and view all the answers

    Which statement accurately describes the sliding filament mechanism?

    <p>Thin filaments slide over thick filaments without changing length</p> Signup and view all the answers

    What is the basic functional unit of a muscle fiber?

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

    How do sodium potassium pumps contribute to muscle cells?

    <p>They help maintain resting membrane potentials</p> Signup and view all the answers

    Study Notes

    Muscle Tissue

    • Muscle tissue is composed of cells specialized for contraction
    • Muscle cells are called myocytes

    Muscle Cell Characteristics

    • Myocyte cytoplasm is called sarcoplasm
    • Myocyte plasma membrane is called sarcolemma
    • Sarcoplasmic reticulum (SR) is a modified endoplasmic reticulum
      • Forms a web-like network surrounding myofibrils
      • Varies in structure in different types of muscle tissue

    Skeletal Muscle Organization

    • Composed of muscle fibers that are long, cylindrical cells

    The Skeletal Muscle Fiber

    • Contains multiple nuclei
    • Contains myofibrils, which are bundles of protein filaments

    Sarcoplasmic Reticulum

    • Network of interconnected tubules that run parallel to myofibrils
    • Stores and releases calcium ions, crucial for muscle contraction

    Structure of the Myofibril

    • Contains three types of myofilaments
      • Thick filaments: composed of myosin protein
      • Thin filaments: composed of actin, tropomyosin, and troponin proteins
      • Elastic filaments: composed of the protein titin; stabilizes myofibril structure and resists excessive stretching

    Myofilament Arrangement and the Sarcomere

    • Myofilaments are arranged into repeating units called sarcomeres
    • Sarcomere: functional contractile unit of a muscle fiber.
      • Bounded by two Z-discs
      • Contains alternating light and dark bands
        • Light band (I band) - only contains thin filaments
        • Dark band (A band) - contains both thick and thin filaments
        • Z discs: located in the center of the I band
          • Anchors thin filaments
          • Attaches myofibrils to each other

    Protein Myofilament Arrangement

    • Sarcomere: The region from one Z-disc to the next
    • Myosin: located in the center of the sarcomere
    • Actin: extends toward the edges of the sarcomere

    Sliding Filament Mechanism of Contraction

    • Actin and myosin filaments slide past each other, shortening the sarcomere
    • The length of the filaments themselves do not change
    • The I band and H zone shorten
    • The A band remains the same length

    Membrane Potential

    • Muscle cells like all cells have a resting membrane potential
    • The difference in electrical charge across the plasma membrane
    • Maintained by sodium potassium pumps
    • Pumps three sodium ions out of the cell for every two potassium ions pumped into the cell

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    Related Documents

    BSc Unit 3 Lecture 1 PDF

    Description

    Explore the structure and function of muscle tissue in this quiz. Understand the characteristics of myocytes, the organization of skeletal muscle, and the role of the sarcoplasmic reticulum in muscle contraction. Test your knowledge on myofilaments and their components.

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