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					Muscles



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PPT Created By: Taira Lynch
  Batesville High School
                   Muscles
• There are more than 600
  muscles in your body.
• Muscles move when
  electrical/chemical
                                  QuickTime™ and a
  signals cause muscle              decompressor
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  cells to contract and
  change in length.
                       Muscle Movement
•   In order to move a bone, it requires
    the cooperation of at least two sets of
    muscles. When one muscle pulls on a
    bone, it moves the bone in one
    direction. Because the muscle cannot
    push on the bone, another muscle is
    needed to pull the bone in the
    opposite direction.
     – Example
           • In order to adduct your
              hand towards your body,
              the biceps brachii, a skeletal
              muscle in the front of your            QuickTime™ and a
              upper arm, contracts and                 decompressor
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              shortens pulling on your
              radius. The triceps brachii
              muscle in the back of your
              upper arm relaxes. To
              abduct your hand away
              from your body, the biceps
              brachii relaxes and the
              triceps brachii contracts
              therefore pulling on ulna.
              The pivot point is the elbow
              joint.
      Tendons and Ligaments
• Tendons
    – connect
      muscles to
      bones
    – made of tough,
      elastic                QuickTime™ an d a
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      tissue
• Ligaments
    – connect bones
      to bones
    – made of tough,
      elastic,
      connective
      tissue
                         Muscle Tone
• Signals from the nervous
  system make a muscle
  generate more force by
  contracting more muscle
  cells.                                Quic kTime™ and a
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• Your nervous system
  sends signals to SOME of
  the muscle cells in all of
  your muscles, even when
  you are at rest. As one set
  of cells tire, signals are
  sent to another set; so
  your skeletal muscles are
  always partly contracted.           QuickTime™ an d a
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  Constant, partial
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  contraction of muscles is
  known as muscle tone.
The Neuromuscular Junction


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            Fast Twitch Vs. Slow Twitch
                   Muscle Cells
• Every skeletal muscle in the body contains
  two types of muscle cells:
     – Fast twitch muscle cells
     – Slow twitch muscle cells
• Fast twitch muscle cells
     – provide speed and quick movements
        over a short period of time
     – fatigue easily                                 QuickTime™ and a
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• Slow twitch muscle cells                      are neede d to se e this picture.
     – respond more slowly and do not tire
        as quickly
• The amount of fast and slow twitch
  muscles cells in a person’s muscles is an
  inherited trait.
     – Some people have a good balance
        between the two, and some people
        have more than the other.
           » Sprinters, jumpers, and
              weight-lifters tend to have
              more fast twitch muscle cells.
           » Long distance runners and
              cyclists tend to have more slow
              twitch muscle cells.
                                 Exercise
•   Resistance exercise
          • weight lifting
               – Require muscles to
                 overcome the
                 resistance (weight)
                 of another object
          • increases the size
            (muscular hypertrophy),
            strength, and endurance
            of skeletal muscles               QuickTime™ and a
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          • causes fast twitch muscle   are neede d to se e this picture.

            cells to respond which
            fatigue easily
          • good for rehabilitation
            after injury
          • increases bone mass
          • Strengthens the
            abdominal muscles
            necessary for a healthy
            back
                           Exercise
• Resistance exercise
       • In response to
         exercise, these cells
         produce new
         filaments of actin and
         myosin within the
         myofibrils of the
         muscle cells; the              QuickTime™ an d a
         diameter of the                   decompressor
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         myofibrils within the
         muscle cells increase,
         and the entire muscle
         enlarges. The
         enlargement of
         muscles is NOT due
         to the production of
         new muscle cells!
                              Exercise
• Aerobic Exercise
       • Exercise that ensures
         lungs and heart can
         deliver oxygen to
         muscle cells at the same
         rate at which the
         muscle cells are using it             QuickTime™ and a

         to carry out cellular
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         respiration
         (mitochondria
         converting food
         molecules into cell
         energy (ATP))
       • Contractions of muscle
         cells are relatively weak
       • Utilize slow twitch
         muscle cells
                                   Exercise
•   Aerobic Exercise
         • Examples (steady or
            moderate intensity
            activities)
              – Jogging
              – Swimming
              – Walking
         • Benefits
                                               QuickTime™ and a
              – Increases the                    decompressor
                 number of               are neede d to se e this picture.

                 mitochondria in
                 muscle cells
              – Increases the
                 number of capillary
                 networks
                 surrounding muscle
                 cells so that needed
                 nutrients (food,
                 oxygen) can get to
                 muscle cells
                                  Exercise
•   Aerobic Exercise
         • Benefits
               – Strengthens the
                 diaphragm (take
                 deeper breaths
                 therefore allowing
                 more gas exchange
                 with each breath)                 QuickTime™ and a
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                 and heart (allows it        are neede d to see this picture.



                 to pump more blood
                 in fewer beats)
               – All of these changes
                 increase endurance
                 or resistance to
                 muscle fatigue.
         • This type of exercise
            doesn’t cause the size or
            strength of the muscle to
            change.
                                       Exercise
•   Anaerobic Exercise
     – Intense exercise for a short
        amount of time (2 minutes or
        less)
     – Uses fast twitch muscle cells
     – Examples
          • Sprinting
          • Weight lifting
     – Lungs and heart cannot supply              QuickTime™ and a
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        enough oxygen to muscle cells       are neede d to se e this picture.
        because the energy demand is
        too high; as a result,
        mitochondria cannot carry out
        cellular respiration and the cell
        switches to lactic acid
        fermentation (anaerobic
        pathway)
          • The anaerobic pathway
             does not use oxygen
          • Converts glucose into lactic
             acid which causes muscle
             fatigue
                     Not Working Out
• Muscles will shrink or atrophy
  due to a decrease in the number
  of actin and myosin filaments,
  decreasing in size and strength.
• An unused muscle may decrease
  to less than half its size within a
  few months.
• Muscles will also fatigue easily
  due to decreased capillary
  networks within the muscle and              QuickTime™ and a
  a decreased number of                         decompressor
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  mitochondria within muscle
  cells.
• The fibers of muscles whose
  motor neurons are severed will
  shrink but also may fragment
  and in time be replaced by fat or
  fibrous connective tissue.
  However, reinnervation within
  the first few months following an
  injury may restore muscle
  function.
                Muscle Overuse
• Overusing muscles or not
  properly conditioning
  muscles can lead to
  muscle injury.
• A pulled muscle is the
  overstretching or tearing
                                     QuickTime™ and a
  of a muscle                          decompressor
• When a muscle heals          are needed to see this picture.

  after a tear, its elastin
  fibers are replaced by
  collagen fibers. This is
  bad because collagen
  fibers do not stretch like
  elastin fibers.
                        Steroid Use
• Anabolic steroids are synthetic
  chemicals that resemble the male
  hormone testosterone.
• Males
    – causes bones to stop growing
      which may lead to an
      abnormal looking body
      structure, female-looking
      breasts, shriveled testes,
      brain cancer, severe acne,
      liver damage, heart disease,
      high blood pressure,                  QuickTime™ an d a
      abnormal sperm production,               decompressor
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      kidney damage, mood swings
      and aggression
• Females
    – causes brain cancer, severe
      acne, liver damage, heart
      disease, high blood pressure,
      kidney damage, mood swings
      and aggression, facial hair,
      deepening of the voice, and
      male-pattern baldness

				
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posted:8/2/2011
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