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13 Cards in this Set
- Front
- Back
Step 1
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An action potential travels along an axon membrane to neuromuscular junction.
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Step 2
something opens |
Ca channels open and Ca enters the presynaptic terminal.
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Step 3
something is release |
Acetylcholine is released from the synaptic vesicles in the presyaptic terminal of neuron.
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Step 4
something diffuses |
Acetylcholine diffusion across the synaptic cleft and binds to receptor causing Na channels to open.
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Step 5
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Sodium ions diffuse into the muscle cell. The action potentials travel along the sarcolemma and T tubule membranes.
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Step 6
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Action potential in the T tubules causes the sarcoplasmic reticulum to release Ca.
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Step 7
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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.
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Step 8
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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.
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Step 9
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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.
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Step 10
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The heads of the myosin myofilaments bend, causing the actin myofilaments to slide over the surface of the myosin myofilaments.
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Step 11
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ADP molecules are released from the myosin head.
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Step 12
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ATP molecules bind to the myosin heads and are broken down to ADP and P. Energy is stored in the myosin heads bend back to their resting position.
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Step 13
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As long as Ca remain attached to troponin, and as long as ATP remains available, steps 8 to 11 are repeated.
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