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Muscle and the Sliding filament theory

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Both demonstrate 'striations' or stripes when seen with a microscope ... Functional contractile unit of striated muscle. 2-3 mm in length. Striations ... – PowerPoint PPT presentation

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Title: Muscle and the Sliding filament theory


1
Muscle and the Sliding filament theory
2
Skeletal muscle development
  • Myoblasts
  • one nucleus each
  • lacking myofibrils
  • Myotubes
  • develop myofibrils
  • Many nuclei

3
Skeletal and Cardiac Muscle
  • Both demonstrate striations or stripes when
    seen with a microscope
  • These stripes represent the regular arrangement
    of actin and myosin

4
  • Myosin is a thick protein and looks dark in the
    section
  • Actin is a very small protein and looks pale in
    the section.

The dark ovals are the nuclei of the muscle
cells. There may be up to A 100 nuclei per cell
5
Sarcomeres
  • Functional contractile unit of striated muscle
  • 2-3 mm in length
  • Striations
  • Made up of regular overlapping pattern
  • of actin (thin filaments)
  • myosin (thick filaments)
  • Delineated by Z lines
  • Center line is I band

6
Very close image of muscle
A band myosin I band actin Z lines where the
actin attaches and the end of a sarcomere
7
Muscle contraction
  • When muscle contracts,
  • all of the actin
  • (white in the picture, red in the diagram)
  • will slide over
  • the myosin
  • (black in the picture, green in the diagram).
  • The Z discs will come closer
  • All of these millions of shortenings in one
    muslce will result in muscle contractions

8
Sliding filament mechanism
  • Sarcomeres shortened
  • Thin filaments slide over thick filament
  • Requires ATP
  • The cells source of energy
  • other proteins and calcium

9
Animation of sliding filament
  • http//3dotstudio.com/zz.html
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