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JunglePanther JunglePanther
wrote...
Posts: 17
Rep: 3 0
9 years ago
Please help: Number of the following events of skeletal muscle contraction in order:
 1. Actin binds to the myosin head, and a power stroke occurs as ADP and P dissociate from myosin.
 2. The terminal cisternae of the sarcomplasmic reticulum release calcium ions into the sarcoplasm because of the action potential.
 3. The sarcoplasmic reticulum removes calcium ions from the sarcoplasm, and tropomyosin returns to its original position.
 4. The energy from ATP hydrolysis "cocks" the myosin crossbridge into an upright position.
 5. Acetylcholinesterase degrades acetylcholine in the synaptic cleft.
 6. Calcium ions bind to troponin, which pulls tropomyosin away from actin.
 7. Acetylcholine binds to receptors on the motor end plate and opens cation channels.
 8. ATP binds and causes the actin and myosin to dissociate from one another, after which it is hydrolyzed and myosin is recocked. The cycle repeats.
 9. Sodium ions flood the sardoplasm and initiate and action potential that spreads along the sarcolemma and into the muscle fiber along the T-tubules.

 Thank you for any help!
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rsb
wrote...
9 years ago
Step 1   An action potential travels along an axon membrane to neuromuscular junction.
Step 2something opens   Ca channels open and Ca enters the presynaptic terminal.
Step 3something is release   Acetylcholine is released from the synaptic vesicles in the presyaptic terminal of neuron.
Step 4something diffuses   Acetylcholine diffusion across the synaptic cleft and binds to receptor causing Na channels to open.
Step 5   Sodium ions diffuse into the muscle cell. The action potentials travel along the sarcolemma and T tubule membranes.
Step 6   Action potential in the T tubules causes the sarcoplasmic reticulum to release Ca.
Step 7   Calcium ions bind to tropin molecules, associated with actin myofilaments. The binding causes tropomysin molecules to move into grooves along the actin myofilament, exposing the myosin attachment sites.
Step 8   Muscle contraction requires energy. ATP molecules, bound to the myosin heads, are broken down to ADP and P, releasing energy, which is briefly stored in the myosin head.
Step 9   Some of the stored energy is used to supply the energy for movement of the myosin myofilaments bind to exposed attachment sites on the actin myofilaments, forming cross-bridges. The P are released from the myosin heads.
Step 10   The heads of the myosin myofilaments bend, causing the actin myofilaments to slide over the surface of the myosin myofilaments.
l3leedingstar,  shan989
JunglePanther Author
wrote...
9 years ago Edited: 9 years ago, JunglePanther
My rough guess is :
6,2,9,5,8,3,4,7,1, please correct me if I'm wrong.
yoyoidc
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