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Muscle Tissue and Skeletal Muscle Structure - Anatomy & Physiology

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  • What are the three types of muscle tissue?
    Skeletal, Cardiac, and Smooth muscle.
  • What prefixes are commonly used for muscle-related terms?
    Myo, mys, and sarco.
  • Describe skeletal muscle tissue characteristics.
    Attached to bones or skin, long cylindrical multinucleate cells, striated, voluntary, contract rapidly but tire easily.
  • Where is cardiac muscle found and what are its key features?
    Only in the heart walls, striated, involuntary, can contract without nervous system stimulation.
  • What are the characteristics of smooth muscle tissue?
    Found in walls of hollow organs, non-striated, involuntary, can contract without nervous system stimulation.
  • What are the four special characteristics of muscle tissue?
    Excitability, Contractility, Extensibility, and Elasticity.
  • List four important functions of muscle tissue.
    Movement of bones or fluids, maintaining posture, stabilizing joints, and heat generation.
  • What connective tissue sheaths surround skeletal muscle from outer to inner?
    Epimysium surrounds entire muscle, Perimysium surrounds fascicles, Endomysium surrounds individual muscle fibers.
  • Define origin and insertion in skeletal muscle attachment.
    Origin is the immovable bone attachment; Insertion is the movable bone attachment.
  • What is a sarcomere?
    The smallest contractile unit of a muscle fiber, composed of thick and thin myofilaments between two Z discs.
  • What proteins compose thick and thin filaments in muscle fibers?
    Thick filaments are made of myosin; thin filaments are made of actin, tropomyosin, and troponin.
  • What is the role of titin in muscle fibers?
    An elastic filament that holds thick filaments in place, helps recoil after stretch, and resists excessive stretching.
  • What is the sarcoplasmic reticulum's function in muscle fibers?
    Stores and releases Ca2+ ions to regulate muscle contraction.
  • What are T tubules and their function?
    Extensions of the sarcolemma that penetrate the muscle fiber, conducting impulses deep into the cell.
  • Explain the sliding filament model of muscle contraction.
    Thin filaments slide past thick filaments, increasing overlap and shortening the sarcomere, causing muscle contraction.
  • What happens to the sarcomere bands during contraction?
    I bands shorten, H zones disappear, Z discs move closer, while A bands stay the same length.
  • How do myosin heads contribute to muscle contraction?
    They bind to actin forming cross bridges, then pivot to pull thin filaments toward the sarcomere center.
  • What is the difference in cell shape between skeletal, cardiac, and smooth muscle?
    Skeletal: long cylindrical; Cardiac: branching chains; Smooth: spindle-shaped, uninucleate.
  • How is contraction regulated differently in skeletal, cardiac, and smooth muscle?
    Skeletal: voluntary via somatic nervous system; Cardiac: involuntary via intrinsic system; Smooth: involuntary via autonomic nerves and hormones.
  • What is the source of calcium for contraction in skeletal, cardiac, and smooth muscle?
    Skeletal: sarcoplasmic reticulum; Cardiac and smooth: sarcoplasmic reticulum and extracellular fluid.