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Muscle Tissue and Contraction - Anatomy & Physiology

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Terms in this set (32)

  • Main function of muscle tissue
    Convert chemical energy to mechanical energy to create movement and generate heat.
  • Contractility
    The ability of muscle tissue to forcibly shorten.
  • Extensibility
    The ability of muscle tissue to be stretched.
  • Elasticity
    The ability of muscle tissue to return to its original length after stretching.
  • Excitability
    The ability of muscle tissue to respond to stimuli.
  • Three types of muscle tissue
    Skeletal, Cardiac, and Smooth muscle.
  • Skeletal muscle characteristics
    Connected to bones, voluntary, striated, multinucleated cells.
  • Cardiac muscle characteristics
    Found in the heart, involuntary, striated, single nucleus per cell.
  • Smooth muscle characteristics
    Found in blood vessels and organs, involuntary, non-striated, single nucleus per cell.
  • Muscle fiber
    A long, multinucleated muscle cell surrounded by endomysium.
  • Fascicle
    A bundle of muscle fibers surrounded by perimysium.
  • Whole muscle
    A bundle of fascicles surrounded by epimysium.
  • Connective tissue connections to bones
    Tendon-like cords and aponeuroses-like sheets.
  • Sarcolemma
    The plasma membrane of a muscle fiber that wraps bundles of myofibrils.
  • Myofibrils
    Long, rod-shaped organelles within muscle fibers containing myofilaments.
  • Sarcoplasmic reticulum
    Specialized endoplasmic reticulum that stores and releases Ca+2 ions around myofibrils.
  • Smallest contractile unit of muscle
    The sarcomere.
  • Sliding filament theory
    Muscle shortens as myosin (thick) filaments pull on actin (thin) filaments, increasing overlap without changing filament length.
  • Contractile proteins in sarcomere
    Myosin (thick filament) and actin (thin filament).
  • Regulatory proteins in sarcomere
    Tropomyosin blocks myosin binding sites on actin; troponin binds Ca+2 and moves tropomyosin to expose binding sites.
  • Structural protein in sarcomere
    Titin, which helps sarcomere retain its shape and elasticity.
  • Z disc
    Defines the end of a sarcomere and anchors actin filaments.
  • M line
    Protein line in the middle of the sarcomere that anchors myosin filaments.
  • I band
    Light band containing only actin filaments.
  • A band
    Dark band containing overlapping actin and myosin filaments.
  • H zone
    Central region of the A band with only myosin filaments.
  • Excitation-contraction coupling
    Process where an action potential travels along the sarcolemma and T tubules, triggering Ca+2 release from sarcoplasmic reticulum to initiate contraction.
  • Neuromuscular junction
    Synapse between motor neuron and muscle fiber where acetylcholine is released to stimulate muscle contraction.
  • Role of calcium in muscle contraction
    Calcium binds to troponin, causing tropomyosin to move and expose myosin binding sites on actin.
  • Cross bridge cycle
    Myosin heads bind to actin, perform power stroke pulling actin, release actin upon ATP binding, and recock for next cycle.
  • Power stroke
    The step in the cross bridge cycle where myosin pulls actin, shortening the sarcomere.
  • Effect of ATP depletion on muscle contraction
    Myosin heads remain bound to actin, causing muscle rigidity (rigor mortis).