muscle tissue contraction and metabolism

• Motor Unit


  A motor neuron & all muscle fibers it supplies
• Isotonic Contractions


  Concentric: muscle shortens; Eccentric: muscle lengthens
• Isometric Contractions


  No shortening; constant muscle tension
• Muscle Twitch


  Response of a muscle to a single, brief threshold stimulus
• Graded Muscle Responses


  Variations in degree of muscle contraction
• Temporal Summation


  Results in unfused (incomplete) tetanus
• Fused Tetanus


  No relaxation between stimuli at high frequencies
• Treppe or Staircase Effect


  Gradual increase in tension with immediate restimulation
• Threshold Stimulus


  Stimulus strength at which 1st muscle contraction occurs
• Motor Unit Recruitment


  Brings more muscle fibers into action for precise control
• Muscle Tone


  Constant, slightly contracted state for stability & posture
• Oxygen Debt


  Extra O2 needed after exercise for replenishment & conversion
• Muscle Fatigue


  Physiological inability to contract due to ionic imbalances
• Rigor Mortis


  Post-mortem muscle stiffness indicating time of death
• Cadaveric Spasm


  Extreme post-mortem muscle stiffness indicating mode of death
• Hypertrophy


  Increase in muscle fiber size leading to increased strength
• Length-Tension Relationship


  Muscles contract most strongly at 80-120% of normal resting length
• Pathophysiology of Muscle System


  Disorders caused by injury, genetics, infection, cancer, drugs
• Neuromuscular Disorders


  Muscle system disorders linked to the nervous system
• Parkinson's Disease


  Neurological disorder affecting movement
• Muscular Dystrophy


  Genetic disorder leading to muscle weakness
• Myasthenia Gravis


  Autoimmune disorder causing muscle weakness
• Amyotrophic Lateral Sclerosis (ALS)


  Neurodegenerative disease affecting nerve cells
• Fibromyalgia


  Chronic pain disorder affecting muscles and bones