muscle tissue types and functions

• Skeletal Muscle Tissue


  Attached to bones & skin, striated, voluntary, powerful
• Cardiac Muscle Tissue


  In the heart, striated, involuntary, contracts rhythmically
• Smooth Muscle Tissue


  In walls of hollow organs, not striated, involuntary, slow sustained contractions
• Sarcomere


  Smallest contractile unit of muscle fiber, contains A band, I band, and Z discs
• Z Disc


  Anchors thin filaments, connects myofibrils
• H Zone


  Midregion where filaments do not overlap
• M Line


  Line of protein myomesin holding adjacent thick filaments
• Sliding Filament Model of Contraction

  Myosin heads bind to actin, detach & bind again, propelling thin filaments
• Triad


  T tubule and terminal cisternae of the sarcoplasmic reticulum
• Sarcoplasmic Reticulum


  Stores calcium ions, releases them to trigger muscle contractions
• Muscle Contraction


  Generation of force, may not cause fiber shortening
• Sliding Filament Model


  Thin & thick filaments overlap during contraction, sarcomeres shorten
• Neuromuscular Junction


  Where motor neurons stimulate skeletal muscles
• Excitation-Contraction Coupling


  Action potential along sarcolemma, rise in intracellular Ca2+ levels
• Cross Bridge Cycle


  Myosin heads pull thin filaments toward center of sarcomere
• Axon Terminal


  End of motor neuron forming neuromuscular junction with muscle fiber
• Synaptic Vesicle


  Contains acetylcholine, released at neuromuscular junction
• Acetylcholine


  Neurotransmitter diffusing across synaptic cleft, binding to receptors in sarcolemma
• Myofibril


  Contractile organelle within muscle fiber, composed of sarcomeres
• T Tubule


  Extension of sarcolemma, conducts electrical impulses to stimulate muscle contraction
• I Band


  Lighter region containing only thin filaments
• A Band


  Dark region containing thick and thin filaments, including the H zone
• H Zone (Muscle Anatomy)


  Region within sarcomere where filaments do not overlap
• M Line (Muscle Anatomy)


  Line of protein holding adjacent thick filaments together
• ACh


  Acetylcholine, a neurotransmitter, diffuses across the synaptic cleft and binds to receptors in the sarcolemma.
• Sarcolemma


  Junctional folds of muscle fiber's sarcolemma where ACh binds to receptors.
• Na+


  Sodium ions that pass into the muscle fiber when ACh binding opens ion channels.
• K+


  Potassium ions that pass out of the muscle fiber when ACh binding opens ion channels.
• Acetylcholinesterase


  Enzyme that terminates ACh effects by degrading ACh in the synaptic cleft.
• Action potential (AP)


  Local depolarization and generation of end plate potential on the sarcolemma, followed by the generation and propagation of the AP.
• Repolarization


  The process of restoring the sarcolemma to its polarized state after depolarization.
• Excitation-Contraction (E-C) Coupling


  Sequence of events by which transmission of an AP along the sarcolemma leads to sliding of the myofilaments, including the latent period and Ca2+ release from the sarcoplasmic reticulum.
• T tubules


  Tubular structures that propagate the action potential along the sarcolemma, stimulating Ca2+ release from the sarcoplasmic reticulum.
• Troponin


  Protein to which calcium binds, removing the blocking action of tropomyosin and exposing the active sites for myosin binding during muscle contraction.
• Skeletal Muscle Tissue


  Attached to bones & skin, striated, voluntary, powerful
• Cardiac Muscle Tissue


  In the heart, striated, involuntary, contracts rhythmically
• Smooth Muscle Tissue


  In walls of hollow organs, not striated, involuntary, slow sustained contractions
• Sarcomere


  Smallest contractile unit of muscle fiber, contains A band, I band, and Z discs
• Z Disc


  Anchors thin filaments, connects myofibrils
• H Zone


  Midregion where filaments do not overlap