Cross-Bridge Cycle
Put the cross-bridge cycle in order
cross bridge formation
power stroke
cross bridge detachment
cocking of the myosin head
What does the inflow of sodium cause?
Generation of muscle action potential
Which is the protein that lies in actin?
tropomyosin
What is the first step in the contraction cycle?
ATP hydrolysis
What forms the cross-bridge?
When myosin heads bind to actin
What type of neurotransmitter is released into the neuromuscular junction?
Acetylcholine (ACh)
What is the protein that attaches to tropomyosin?
troponin
What forms the cross-bridge?
When myosin heads bind to actin
What proteins are involved in the cross-bridge cycle?
myosin and actin
What does action potential do?
Travel along transverse tubules to open calcium channels in sarcoplasmic reticulum
What is the function of calcium binding to troponin?
Alters shape of troponin and moves tropomyosin off myosin binding site on actin
What is the event called when myosin crossbridges rotate toward center of sarcomere?
Power stroke
In what stage is ADP and P released and the myosin head pivots and bends, changing to its bent low-energy state. As a result it pulls the actin filament toward the M line.
Power Stroke
What happens when ACh is released?
Activation of ACh receptors in motor end plate that open sodium channels.
What happens when calcium levels get low in sarcoplasm?
troponin-tropomyosin complex slides back into position blocking myosin binding sites on actin
What causes myosin to detach from actin?
ATP binding to myosin head