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Muscular System - Anatomy & Physiology Exam III Study Guide

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Termini in questo insieme (29)

  • Four characteristics of muscle tissue
    Excitability, contractility, extensibility, and elasticity
  • Functions of muscles
    Movement, posture maintenance, joint stabilization, and heat generation
  • Connective tissue sheaths in muscle anatomy
    Epimysium surrounds the whole muscle, perimysium surrounds fascicles, endomysium surrounds individual muscle fibers
  • Difference between tendons and aponeurosis
    Tendons are cord-like structures connecting muscle to bone; aponeurosis is a broad, flat sheet of connective tissue
  • Sarcolemma and sarcoplasm
    Sarcolemma is the muscle fiber plasma membrane; sarcoplasm is the cytoplasm inside the muscle fiber
  • Role of sarcoplasmic reticulum in muscle contraction
    Stores and releases calcium ions needed to trigger contraction
  • Function of T-tubules
    Transmit action potentials deep into the muscle fiber to trigger calcium release
  • Myofilaments in muscle fibers
    Actin (thin filaments) and myosin (thick filaments) responsible for contraction
  • Sarcomere structure components
    Z discs mark sarcomere boundaries, M line is center of thick filaments, I band contains thin filaments only, A band contains thick filaments
  • Role of troponin and tropomyosin during contraction
    Troponin binds calcium to move tropomyosin off actin binding sites, allowing myosin to bind
  • Triad in muscle fibers
    Two terminal cisterns of sarcoplasmic reticulum and one T-tubule between them
  • Sliding filament model of contraction
    Actin filaments slide over myosin filaments, shortening the sarcomere and contracting the muscle
  • Neuromuscular junction components
    Axon terminals release acetylcholine into synaptic cleft, which binds receptors on junctional folds of sarcolemma
  • Events at neuromuscular junction during contraction
    Acetylcholine release, binding to receptors, depolarization of sarcolemma, triggering muscle excitation
  • Excitation-contraction coupling
    Process linking muscle fiber excitation to calcium release and contraction initiation
  • Cross bridge cycle
    Myosin heads attach to actin, pivot, detach, and re-cock to pull thin filaments
  • Myasthenia gravis
    Autoimmune disease causing weakness by blocking acetylcholine receptors at neuromuscular junction
  • Difference between depolarization and repolarization
    Depolarization is membrane potential becoming more positive; repolarization is returning to resting negative potential
  • Refractory period in muscle fibers
    Time during which muscle fiber cannot be re-excited after an action potential
  • Isotonic vs isometric contraction
    Isotonic changes muscle length with movement; isometric generates force without changing length
  • Motor unit
    One motor neuron and all the muscle fibers it innervates
  • Muscle twitch phases
    Latent period, period of contraction, and period of relaxation
  • Temporal summation and tetanus
    Multiple stimuli increase contraction strength; incomplete tetanus has partial relaxation, complete tetanus has none
  • Muscle response to stimulus strength
    Recruitment activates more motor units to increase contraction force
  • Muscle tone
    Continuous, passive partial contraction of muscles for posture and readiness
  • ATP functions in muscle contraction
    Provides energy for cross bridge cycling, calcium pumping, and direct phosphorylation
  • Energy pathways for ATP production in muscle
    Direct phosphorylation, anaerobic glycolysis, and aerobic respiration
  • Muscle groups roles: prime mover, antagonist, synergist
    Prime mover causes main action, antagonist opposes it, synergist assists the prime mover
  • How muscles are named
    Based on location, shape, number of origins, fascicle direction, attachments, or action