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Muscle Tissue and Skeletal Muscle Structure Chapter 9

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Terms in this set (20)

  • What are the three types of muscle tissue?

    Skeletal, Cardiac, and Smooth muscle tissues.

  • What are the key characteristics of skeletal muscle tissue?

    Attached to bones/skin, elongated multinucleate fibers, striated, voluntary, contracts rapidly, requires nervous system stimulation.

  • How does cardiac muscle differ from skeletal muscle?

    Found only in heart walls, striated, involuntary, can contract without nervous system stimulation, branched cells with intercalated discs.

  • What are the characteristics of smooth muscle tissue?

    Located in walls of hollow organs, non-striated, involuntary, can contract without nervous system stimulation, spindle-shaped cells.

  • Name the connective tissue sheaths of skeletal muscle from outermost to innermost.

    Epimysium surrounds entire muscle, Perimysium surrounds fascicles, Endomysium surrounds individual muscle fibers.

  • What is the difference between direct and indirect skeletal muscle attachments?

    Direct attachment: epimysium fused to bone periosteum. Indirect attachment: connective tissue extends as tendon or aponeurosis.

  • Describe the microscopic anatomy of a skeletal muscle fiber.

    Long cylindrical cell with multiple peripheral nuclei, sarcolemma (plasma membrane), sarcoplasm (cytoplasm), contains myofibrils, sarcoplasmic reticulum, and T tubules.

  • What are myofibrils and what do they contain?

    Densely packed rodlike elements making up ~80% of cell volume, containing sarcomeres which are contractile units composed of myofilaments.

  • What is a sarcomere?

    The smallest contractile unit of a muscle fiber, extending from one Z disc to the next, composed of thick and thin myofilaments.

  • What proteins compose thick and thin filaments in muscle fibers?

    Thick filaments are made of myosin, thin filaments are made of actin, with regulatory proteins tropomyosin and troponin.

  • What is the role of titin in muscle fibers?

    Titin is an elastic filament that holds thick filaments in place, helps recoil after stretch, and resists excessive stretching.

  • What is the function of the sarcoplasmic reticulum (SR) in muscle fibers?

    Network of smooth ER surrounding myofibrils, stores and releases calcium ions (Ca2+) to regulate contraction.

  • What are T tubules and their function?

    Extensions of the sarcolemma that penetrate the muscle fiber, conducting impulses deep into the fiber to trigger calcium release from the SR.

  • What is a triad in skeletal muscle fibers?

    A structure formed by a T tubule flanked by two terminal cisterns of the sarcoplasmic reticulum, important for excitation-contraction coupling.

  • Explain the sliding filament model of muscle contraction.

    During contraction, thin filaments slide past thick filaments, increasing actin-myosin overlap, shortening the sarcomere and muscle fiber.

  • What happens to the sarcomere bands during muscle contraction?

    I bands shorten, Z discs move closer, H zones disappear, A bands stay the same length.

  • What are the special characteristics of muscle tissue?

    Excitability (respond to stimuli), Contractility (shorten forcibly), Extensibility (stretch), Elasticity (recoil to resting length).

  • List four important functions of muscle tissue.

    Movement of bones/fluids, maintaining posture, stabilizing joints, heat generation.

  • What is the role of dystrophin in muscle fibers?

    Links thin filaments to proteins of the sarcolemma, helping maintain muscle fiber integrity.

  • How do skeletal muscle fibers receive nutrients and oxygen?

    Each muscle is served by one artery, one nerve, and one or more veins that branch through connective tissue sheaths.