Skeletal Muscles

Outer most sheet- epimysium

• fascicles

• 1 fasicle is covered by perimysium

• Inside fascicles= muscle fibers (cells)

• Muscle fibers are enclosed within endomysium

• Inside muscle fibers= myofibrils

• sarcolemma- plasma membrane of muscle cell

  
  

Myofibrils

• rods that are striated

• Myofilaments

  • Actin

  • Myosin

• Covered by sarcoplasmic reticulum- storage and regulation of Ca2+ ions

• T tubules- lie on sarcolemma

• Terminal cisternae

  • T tubules and cisternar= triad

  

• troponin is activated by Ca, then tropomyosin moves and myosin heads can detach and move

  • Cross bridges

  • Power stroke- cross bridges allow myosin head to move toward M line. Actin filaments will be brought closer to M line

  • Sarcomere shortens

• Sarcomere- between Z discs

Endomysium→sarcolemma→myofibrils (SR around it)

H zone- only myosin

A band- overlap of actin and myosin

I band- only actin