The Muscular System

Jump To: Function; Voluntary or Involuntary; Anatomy of a Muscle; Parts of a Sarcomere; Sliding Filament Theory; Bibliography

  • produce movement
  • maintain posture
  • stabilize joints
  • generate heat

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Voluntary or Involuntary

Voluntary muscles are moved with consious thought. Involuntary muscles do not require conscious effort to work.

Skeletal Muscle
Cardiac Muscle
Smooth Muscle
voluntary movement
involuntary movement
involuntary movement
typically attached to bone
lines many internal organs
*The term striated means that the muscle has a striped appearance

Skeletal Muscle
Skeletal Muscle


Cardiac Muscle
Cardiac Muscle


Smooth Muscle


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The Muscle Song...... =)

annie-- anatomy and phys.wmv

Anatomy of a Muscle

Epimysium: the outermost layer of a muscle, made of very tough connective tissue
Perimysium: below the epimysium, made of connective tissue, covers the fascicles (bundles of muscle cells)
Endomysium: a thin connective tissue covering each muscle fiber
Muscle Fiber: a single muscle cell, long and contains many nuclei
Myofibril: an organelle that is plentiful in muscle fibers
Sarcomere: repeating units of actin and myosin filaments

Actin: a thin filament
Myosin: a thick filament

Muscle Anatomy

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Parts of a Sarcomere
Z Disc/Line: membranes to which actin filaments are attached, a sarcomere spans from one Z Disc to another.
A Band: dark bands, contain both actin and myosin filaments
I Band: light bands, contain only actin filaments, span across parts of two different sarcomeres
H Zone: contains only thick myosin filaments
Crossband (Myosin Head): connect actin and myosin filaments


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Sliding Filament Theory
  1. The myosin head attached to the actin myofilament
  2. The myosin head pivots and pulls the actin filaments toward the center of the sarcomere shortening it
  3. New ATP attaches to the crossband causing it to detach from the actin
  4. ATP is converted into ADP and the crossband is ready to attach to the actin filament again

*This video has audio, so please turn up the volume! :D

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Skeletal Muscle - Mobley, Laney. "KC Biology 2401: Human Anatomy and Physiology". 6/4/10 <>.
Cardiac Muscle - Mobley, Laney. "KC Biology 2401: Human Anatomy and Physiology". 6/4/10 <>.
Smooth Muscle - Mobley, Laney. "KC Biology 2401: Human Anatomy and Physiology". 6/4/10 <>.
Muscle Anatomy - Hill, Eric. "Background: Muscle Physiology and Development". Ohio State University. 6/8/10 <>.
Sarcomere - Matthews, Gary . "Sliding Filament Theory". Blackwell Publishing. 6/8/10 <>.
Sliding Filament Theory - kunderwood. "Sliding Filament Theory". Teachertube. 6/8/10 <>.
Skeletal, Cardiac, and Smooth cartoon - Unknown, Unknown. "General Princepals of Pathophysiology". Unknown. 6/14/10 <>.

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