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Ch.9 Part 1 & 2

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Terms in this set (26)

  • What are the three types of muscle tissue?
    Skeletal, Cardiac, and Smooth muscle tissues.
  • What prefixes are commonly used in muscle terminology?
    Myo, mys, and sarco.
  • What are the key characteristics of skeletal muscle?
    Skeletal muscle is striated, voluntary, attached to bones and skin, contracts rapidly, and tires easily.
  • What distinguishes cardiac muscle tissue?
    Cardiac muscle is striated, involuntary, found only in the heart, and contracts at a steady rate due to its pacemaker.
  • Where is smooth muscle found and what are its characteristics?
    Found in walls of hollow organs, smooth muscle is nonstriated and involuntary.
  • What are the four main characteristics shared by all muscle tissue?
    Excitability, contractility, extensibility, and elasticity.
  • List four important functions of muscle tissue.
    Produce movement, maintain posture, stabilize joints, and generate heat.
  • What connective tissue sheaths surround skeletal muscle from external to internal?
    Epimysium surrounds entire muscle, perimysium surrounds fascicles, and endomysium surrounds individual muscle fibers.
  • Define origin and insertion in muscle attachments.
    Origin is attachment to immovable bone; insertion is attachment to movable bone.
  • What is a sarcomere?
    The smallest contractile unit of a muscle fiber, extending from one Z disc to the next.
  • What proteins compose thick and thin myofilaments?
    Thick filaments are made of myosin; thin filaments are made of actin, with regulatory proteins tropomyosin and troponin.
  • What is the role of the sarcoplasmic reticulum in muscle fibers?
    It stores and releases Ca2+ ions to regulate muscle contraction.
  • What is the function of T tubules in muscle fibers?
    They conduct electrical impulses deep into the muscle fiber to trigger Ca2+ release from the sarcoplasmic reticulum.
  • Describe the sliding filament model of muscle contraction.
    Thin filaments slide past thick filaments, increasing overlap and shortening the sarcomere without changing filament length.
  • What are the four steps of the cross bridge cycle?
    1. Cross bridge formation, 2. Power stroke, 3. Cross bridge detachment, 4. Cocking of myosin head.
  • What causes rigor mortis after death?
    Lack of ATP prevents detachment of myosin heads from actin, causing sustained muscle contraction.
  • What is the neuromuscular junction (NMJ)?
    The synapse between a motor neuron axon terminal and a muscle fiber's sarcolemma.
  • What neurotransmitter is released at the NMJ to stimulate muscle contraction?
    Acetylcholine (ACh).
  • What are the three phases of an action potential in muscle fibers?
    1. End plate potential, 2. Depolarization, 3. Repolarization.
  • What is excitation-contraction coupling?
    The process linking the action potential propagation along the sarcolemma to the sliding of myofilaments causing contraction.
  • How does calcium regulate muscle contraction?
    Ca2+ binds to troponin, causing tropomyosin to move and expose myosin-binding sites on actin.
  • What is a motor unit?
    A motor neuron and all the muscle fibers it innervates.
  • What is the difference between isotonic and isometric contractions?
    Isotonic contractions change muscle length and move load; isometric contractions generate force without changing length.
  • Name the three pathways for ATP regeneration in muscle contraction.
    Direct phosphorylation by creatine phosphate, anaerobic glycolysis, and aerobic respiration.
  • What causes muscle fatigue?
    Ionic imbalances, increased inorganic phosphate, decreased ATP, and decreased glycogen can contribute to fatigue.
  • What is excess postexercise oxygen consumption (EPOC)?
    The extra oxygen required to restore muscle to resting state after exercise.