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Muscular System - Anatomy & Physiology

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Termini in questo insieme (28)

  • What are the three types of muscular tissue?
    Skeletal muscle, cardiac muscle, and smooth muscle.
  • Where is skeletal muscle located and what is its cell shape?
    Attached to bones or skin; cells are long, cylindrical, multinucleate, and striated.
  • What distinguishes cardiac muscle cells?
    Branching chains of cells; uni- or binucleate; striated; found in heart walls.
  • Describe smooth muscle cells.
    Single, spindle-shaped, uninucleate cells without striations; found in walls of hollow organs.
  • What are the four key characteristics of muscular tissue?
    Excitability, contractility, extensibility, and elasticity.
  • Define excitability in muscle tissue.
    Ability to receive and respond to stimuli by producing a muscle action potential.
  • What is contractility in muscles?
    The ability of muscles to shorten or lengthen while generating force.
  • What is the function of extensibility in muscle tissue?
    Muscle tissue can be stretched or extended without damage.
  • Explain elasticity in muscles.
    Muscles return to their original shape after being stretched.
  • List five functions of muscular tissue.
    Produce body movements, stabilize body positions and joints, move substances within the body, generate heat, and regulate blood glucose concentration.
  • What are the connective tissue wrappings of skeletal muscle from outer to inner?
    Epimysium surrounds the whole muscle, perimysium surrounds fascicles, and endomysium surrounds individual muscle fibers.
  • What is a fascicle?
    A discrete bundle of muscle cells surrounded by perimysium.
  • Describe a muscle fiber.
    An elongated multinucleate muscle cell with a striated appearance, surrounded by endomysium.
  • What is fascia?
    Collagen-rich fibrous connective tissue covering skeletal muscles, separating muscles or groups from each other.
  • What is a motor unit?
    A motor neuron and all the muscle fibers it innervates.
  • Explain the all-or-none principle of muscle contraction.
    When a motor unit is stimulated, all muscle fibers in that unit contract fully; no partial contractions occur.
  • What factors affect the maximum tension a muscle can generate?
    Frequency of nerve impulses, size of motor units, amount of stretch before contraction, and nutrient/oxygen availability.
  • What is the length-tension relationship in muscle contraction?
    The amount of stretch before contraction affects the force a muscle can generate.
  • What are the types of skeletal muscle fibers?
    Type I (slow oxidative), Type IIa (fast oxidative-glycolytic), and Type IIb (fast glycolytic).
  • What is muscular hypertrophy?
    An increase in muscle fiber diameter caused by repeated mechanical overload and stimulated by hormones.
  • What causes muscular atrophy?
    Disuse or denervation leading to a decrease in muscle fiber diameter and loss of myofibrils.
  • What is the sarcomere?
    The basic functional unit of skeletal muscle fibers, composed of thick and thin filaments between two Z discs.
  • Name the contractile proteins in muscle fibers.
    Actin (thin filaments) and myosin (thick filaments).
  • What role do troponin and tropomyosin play in muscle contraction?
    They are regulatory proteins that block or expose myosin binding sites on actin to control contraction.
  • Describe the four steps of cross-bridge cycling.
    1. Cross bridge formation, 2. Power stroke, 3. Cross bridge detachment, 4. Cocking of myosin head.
  • What is muscle fatigue?
    The inability of muscle to maintain force after prolonged activity due to factors like calcium depletion and lactic acid buildup.
  • What is muscle tone?
    A small amount of continuous tension in muscles due to weak, alternating contractions of motor units.
  • Differentiate isotonic and isometric muscle contractions.
    Isotonic: muscle length changes with constant tension; Isometric: muscle length stays the same with tension insufficient to move load.