Muscular System

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Muscular System
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My muscles are important because they

• Hold my organs in place
• Hold my bones together so that I can move
• Help me chew my food
• Open and close my eyelids
• Pump my blood
• Allow me to run and play
• Help me to smile!

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What are muscles made of?

• Stretchy, elastic cells and fibers
• What else is stretchy like a muscle?

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Did you know that ?

• more than 50 of body weight is muscle !
• more then 60 of your body heat is generated by
  muscle contractions maintain body temperature
• -You have over 650 muscles
• -It takes more muscles to frown then it does to
  smile

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Three types of muscle
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Classification of muscle
Skeletal
Cardiac
Smooth
Note Control, Location and Structure
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Skeletal muscle

• Large muscles

Maintain posture

• Facilitate locomotion
• PULL ON BONES

Move jointed bones
Found in antagonistic pairs

• Attached to bones by tendons

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Structure of skeletal muscle

• Each cell (fibre) is long and cylindrical
• Muscle fibres are multi-nucleated more then one
  nucleus
• Have large number of mitochondria organelle
  that produces ATP (energy)

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Skeletal muscle - Summary

• Voluntary movement of skeletal parts
• Spans joints and attached to skeleton
• Multi-nucleated, striated, cylindrical fibres

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Cardiac muscle

• Main muscle of heart
• Pumping mass of heart
• Critical To Life
• Heart muscle cells behave as one unit
• Heart always contracts to its full
  extent

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Structure of Cardiac Muscle Cells

• (fibres) are short, branched and interconnected
• striated multi-nucleated
• Adjacent cells joined via electrical synapses
  (gap junctions)

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Cardiac muscle - Summary

• Found in the heart
• Involuntary rhythmic contraction
• Branched, striated fibre with single nucleus and
  intercalated discs

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Smooth muscle

• Lines walls of viscera (organs)
• Found in longitudinal or circular arrangement
• Alternating contractions of muscles in the
  digestive system leads to peristalsis

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Structure of Smooth Muscle Cells

• uni-nucleated (one nucleus) cells
• Striations not observed
• Actin and myosin filaments are present
• Ratio of thin-to-thick filaments is 161 (in
  striated muscle this is 21)
• Myosin filaments are attached todense bodies at
  the end of eachcell

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Smooth muscle - Summary

• Found in walls of hollow internal organs
• Involuntary movement of internal organs
• Elongated, spindle shaped fibre with single
  nucleus

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Muscle Control
Skeletal
Skeletal
Cardiac
Smooth