ANAPHY MID

• Myology


  The study of muscles
• Voluntary movement

  Self-generated, controlled by neurons
• Contraction

  Allows the body to move, no rapid relaxation
• Striated


  Striped appearance (nonstriated opposite)
• Sarcoplasm


  Cytoplasm of the muscle fiber
• Sarcolemma


  Plasma membrane of the muscle fiber
• Tendons

  Cord-like connective tissue
• Aponeurosis


  When the connective tissue extends as a broad, flat, sheet
• Types of muscle tissue

  • Skeletal muscle tissue
  • Cardiac muscle tissue
  • Smooth muscle tissue
• Skeletal muscle tissue

  • Moves the bones of the skeleton, striated, voluntary
• Cardiac muscle tissue


  • Forms most of the heart wall, striated, involuntary
• Smooth muscle tissue

  • In the walls of hollow internal structures, nonstriated, involuntary
• Autorhythmicity


  The heart's natural pacemaker
• Functions of muscle tissue


  • Body movement
  • Stabilization
  • Storing and moving nutrients within the body
  • Generating heat (thermogenesis)
• Sphincters


  Ring-like bands of smooth muscle tissue, surrounding an opening
• Muscle actions

  • Agonist (prime mover, does the action)
  • Antagonist (opposes the action)
  • Synergist (undesirable movement)
  • Fixation (fixes position)
• Muscle functions

  • Flexor (bends a limb)
  • Extensor (straightens a limb)
  • Adductors (toward midline)
  • Abductors (away from midline)
  • Pronators (turn or rotate a part downward on its axis)
  • Supinators (turn or rotate a part upward on its axis)
  • Elevator (raises or lifts a part)
  • Depressors (lower or depress a part)
  • Constrictors (compresses a space)
  • Dilators (widens a space)
  • Sphincters (surrounds an opening)
• Electrical excitability

  • The ability to respond to certain stimuli by electrical signals (action potentials)
• Contractility

  • The ability to contract forcefully
• Tension

  The force of contraction
• Extensibility


  Stretch without being damaged
• Elasticity

  Return to its original length
• Levels of organization within a skeletal muscle

  • Skeletal muscle (organ)
  • Fascicle (bundle of muscle fibers)
  • Muscle fiber (cell)
  • Myofibril (contractile elements)
  • Filaments (contractile proteins)
• Contraction cycle

  1. ATP hydrolysis

  2. Attachment of myosin to actin (forming a cross-bridge)

  3. Power stroke (myosin head pivots)

  4. Detachment of myosin from actin (myosin head binds ATP)
• Excitation-contraction coupling

  The sequence of events that links excitation (a muscle action potential) to contraction (sliding of the filaments)
• Length-tension relationship


  How the forcefulness of muscle contraction depends on the length of the sarcomeres within a muscle before a contraction begins
• Components of the neuromuscular junction

  • Somatic motor neuron
  • Neurotransmitter (acetylcholine)
  • Axon terminal
  • Synaptic end bulbs
  • Synaptic vesicles
  • Motor end plate
  • ACh receptors
• Muscle action potential production at the neuromuscular junction

  1. Release of ACh

  2. Activation of ACh receptors

  3. Production of muscle action potential

  4. Termination of ACh activity (by acetylcholinesterase)
• Muscle metabolism pathways

  • Creatine phosphate
  • Anaerobic glycolysis
  • Aerobic respiration
• Muscle fatigue


  The inability of a muscle to maintain force of contraction after prolonged activity
• Central fatigue


  Caused by changes in the central nervous system (brain and spinal cord)
• Oxygen debt

  The added oxygen, over and above the resting oxygen consumption, that is taken into the body after exercise
• Recovery oxygen uptake


  Elevated use of oxygen after exercise, better term than oxygen debt
• Muscle tension

  Force generated by the contraction of the muscles
• Motor units

  Consists of a somatic motor neuron plus all of the skeletal muscle fibers it stimulates
• Recruitment


  Process known by increasing the number of active motor units
• Phases of a twitch contraction

  • Latent period
  • Contraction period
  • Relaxation period
  • Refractory period
• Wave summation


  Stimuli arriving at different times cause larger contractions
• Unfused (incomplete) tetanus

  When a skeletal muscle fiber is stimulated at a rate of 20 to 30 times per second, it can only partially relax between stimuli
• Fused (complete) tetanus


  When a skeletal muscle fiber is stimulated at a higher rate of 80 to 100 times per second, it does not relax at all