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9 Cards in this Set

  • Front
  • Back
Step 1
The motor nueron at the nueromuscular junction releases ACH to bind to the sarcolemma of the skeletal muscle fiber (cell) Signal the start of the contraction
Step 2
The signal is spread throughout the sarcolemma of skeletal muscle fiber (cell)
Step 3
The signal is spread down t-tubles to center of cell
Step 4
T-tubles spread signal to cell interior and pass signal to the sarcoplasmic reticulum, this causes the release of calcium ions from SR
Step 5
Calcium ions combine with the troponin-tropomyosin complex on actin exposing binding sites for myosin
Step 6
Myosin crossbridge heads (with ATP attached) do not attach to actin (This si the low affinity state)
Step 7
Myosin heads cause ATP to split (hydrolosis of ATP ->ADP+inorganic phosphate) causing mypsin crossbridge heads to swivel to ready position and attach to exposed binding sites on actin. Myosin is cocked (This is high affinity)
Step 8
Attachment of myosin and actin results in ATP+inorganic phosphate release, actin 'slides' past myosin (sarcomeres shorten/muscle cell shortens/Zlines pulled together)
Step 9
To release myosin-actin, another ATP molecule binds to myosin heads, resulting in the release of crossbridge attachment to actin (retunring to low affinity state)