7 - 9) Exposed actin sites bind with the myosin heads,...

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Sheet1 Page 1 Excitation-Contraction Coupling (Figures 8-7,8-8,8-9,8-11,8-12) Muscular contraction occurs when the thick and thin filaments within a sarcomere slide past one another. This sliding action is m (note, the list below is more complete than that shown in figure 8-12) 1) End plate potential at the neuromuscular junction. 2) Action potential in the muscle fiber mediated by voltage-gated Na+ and K+ channels. 3) Propagation of the action potential into the transverse tubules. 4) Activation of the voltage-gated dihydropyridine receptors in the transverse tubules. 5) Opening of the foot proteins in the lateral sacs. 6) Release of Ca++ into the cytoplasm. 7) Binding of Ca++ to troponin molecules. 8) Conformational change of troponin which acts to change the configuration of the troponin-tropomyosin complex and expose
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Unformatted text preview: 9) Exposed actin sites bind with the myosin heads, which have been previously energized by hydrolysis of ATP at the ATPase 10) Binding of actin and myosin causes the cross-bridge to bend and pull the thin filament inward causing the sarcomere to sh o 11) ATP binds to the myosin head causing the head to relax back to the resting position. 12) ATP is hydrolyzed by the myosin ATPase re-energizing the myosin protein head. 13) Ca++ is actively transported back into the sarcoplasmic reticulum. 14) After Ca++ is removed and the action potential has ceased, the troponin-tropomyosin complex returns to its original config u...
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