BMS 100 - Chapter 8 Outline
    Muscle Tissue (see Ch. 5)
  • Properties of muscle tissue include:
    1. ability to generate action potentials (AP's), like neurons
    2. ability to contract (become shorter) and generate force when stimulated by AP's
  • Three types of muscle tissue
    1. Skeletal muscle tissue - skeletal muscles are usually attached to bones
      1. Skeletal muscle fibers are elongated cells with multiple nuclei.
      2. Control is voluntary (under “conscious control”).
      3. "origin" = less movable point of attachment; "insertion" = more movable point of attachment
      4. True or false? The muscles of pulmonary ventilation (breathing) are skeletal muscles.
    2. Smooth muscle tissue - located mainly in the walls of hollow organs
      1. When smooth muscle in the iris _?_, the pupil _?_.
      2. propels contents of tubular organs such as intestines, etc.
      3. necessary for constriction of blood vessels (maintains BP), airways, etc.
      4. Control is involuntary.
    3. Cardiac muscle tissue - present only in the heart
      1. Fibers (cells) are branched and joined into a network that contracts as a unit.
      2. Cardiac muscle generates its own AP's – natural “pacemaker” function.
      3. Cardiac muscle contractions last longer than do skeletal muscle contractions.
      Structure of a Skeletal Muscle (Ch. 8)
  • each muscle is an organ
  • fascicles = bundles of fibers within a muscle
  • fibers (cells) are bundled together within fascicles
  • myofibrils = rods within fibers (sarcomeres = sections within myofibrils)
  • myofilaments (thick filaments, thin filaments) are precisely arranged within myofibrils
    1. thin filaments - are composed of actin molecules and attached to "Z discs"
    2. thick filaments - are composed of myosin molecules (with "heads") and suspended between thin filaments
    3. partial overlap between thin and thick filaments produces striations
      Contraction of Muscle (Ch. 8)
  • motor neurons - conduct AP's from CNS to muscles
  • AP's cause muscles to contract
  • major steps in muscle contraction
    1. “heads” of thick filaments attach to and form "cross-bridges" with thin filaments
    2. heads re-orient and pull on thin filaments
    3. the thin filaments are drawn toward the center of each sarcomere
  • What actually becomes shorter when a muscle contracts?
    thick filaments OR thin filaments OR sarcomeres Study Questions at OLC, Chapter 5 – 17, 18, 32, 36, 37, 39
    Study Questions at OLC, Chapter 8 - 3, 4, 5, 6, 8, 10, 12, 14, 19, 29, 32, 35, 36, 41
    Online Animations (available from online version of this outline)
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    Spring 2011