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The Muscular System

Learn about the integumentary, skeletal, and muscular systems and their functions. Explore different types of muscles and understand muscle contraction physiology.

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The Muscular System

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  1. The Muscular System • 2.0 TSW explore the integumentary, skeletal, muscular systems and relate structures of the various parts to the functions they serve • 2.3 TSW Illustrate the various kinds of muscles, including the major muscles of the body and explain the physiology of muscle contraction.

  2. Muscle Tissues • Skeletal • Cardiac • Smooth

  3. Skeletal Muscle Tissues • Muscle Fibers- individual threads in muscle tissue Three Names • Skeletal Muscle-attaches to bone • Striated muscle- cross stripes • voluntary muscle-contractions are controlled

  4. Makes up most of the heart Cross striations with dark bands called Intercalated Disks Interconnected fibers help it contract as a unit Cardiac Muscle Tissue

  5. Nonstriated Involuntary Single nucleus Forms walls of blood vessels and many hollow internal organs Smooth Muscle Tissue

  6. Which is it?

  7. Which is it? Skeletal A B. C. Smooth Cardiac

  8. Most skeletal muscle start on one bone and end on another, crossing a joint in the middle Structure of Skeletal Muscle

  9. Origin- the attachment of the muscle to the more stationary bone Insertion- attachment to the more movable bone Tendons- anchor muscle to bone

  10. Bursae- tiny fluid filled sacs between bones and tendons Lined with slippery synovial membrane Filled with synovial fluid Tendon sheaths- enclose some tendons Lined with synovial membrane Filled with synovial fluid Aids for movement

  11. How does a contraction happen? (…deep breath…) • Muscle fiber- specialized contractile cell • Each skeletal fiber is filled with 2 kinds of thin, threadlike structures called Thick and Thin myofilaments • Thick myofilaments are formed by a protein called Myosin • Thin myofilaments are formed by the protein Actin • Sacrcomere- the basic functional, contractile unit of skeletal muscle

  12. Sliding Filament Model • During a contraction thick and thin myofilaments attach to each other forming “bridges” • These bridges act as levers to pull the myofilaments past each other • Calcuim must be present- released into the cytoplasm by a nerve impulse • Shortening of the muscle cell also requires energy, which it gets from the break down of adenosine triphosphate (ATP)

  13. http://www.youtube.com/watch?v=0kFmbrRJq4w&feature=related http://www.youtube.com/watch?v=boPT3H1tAaI&feature=related

  14. Functions of Skeletal Muscle • Movement • Prime mover (Agonist)- doing the main movement {bicep} • Synergist- helps the prime mover {brachioradialis} • Antagonist- opposite/relaxes {triceps} • Posture and Muscle Tone • Tonic contraction • Heat Production

  15. Types of Contractions • Twitch- quick jerky response to stimuli • Tetanic- more sustained than twitch, stimuli rapidly bombards the muscle • Isotonic- muscle changes in length, producing movement • Isometric- muscle pulls forcefully against a load but doesn’t shorten or produce movement

  16. Effects of exercise • Atrophy- decrease in muscle mass due to inactivity • Hypertrophy- increase in muscle mass due to exercise • Strength training- increases hypertrophy • Endurance training- increases amount of time a muscle can do an activity

  17. Rigor Mortis • Latin for “stiffness in death” • Myosin/actin cross bridges of muscle fibers stimulated at time of death are still attached • Once the cells die there is no ATP left to allow them to release leaving the bridges stuck in the contracted position

  18. Muscle Disorders (myopathies) • Strain- overuse or trauma to the muscle resulting in overuse or tearing • Cramps- painful involuntary twitches or muscle spasms. May be caused by myositis, other irritation, or an ion or water imbalance • Contusion- a bruise • Myositis – muscle inflammation • Fibromyositis- muscle and tendon inflammation • Poliomyelitis- (polio) viral infection of the nerves that control skeletal muscle movement

  19. Muscular Dystrophy • Group of genetic diseases characterized by skeletal muscle atrophy • Some are fatal • Duchenne MD- most common form • False muscle growth look caused by muscle being replaced by fat • Death usually occurs before age 21 • http://www.youtube.com/watch?v=6wLnR7GJakY • http://www.youtube.com/watch?v=lVR0le9gRfU&feature=related • http://www.fightdmd.com/about-fightdmd/our-story

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