Cardiovascular Physiology (心血管生理学) Qiang XIA(夏强),MD&PhD Department of Physiology Room C518, Block C, Research Building, School of Medicine Te:88208252 Email:xiaqiang@zju.edu.cn
Cardiovascular Physiology （心血管生理学） Qiang XIA (夏强), MD & PhD Department of Physiology Room C518, Block C, Research Building, School of Medicine Tel: 88208252 Email: xiaqiang@zju.edu.cn
Excitation-Contraction Coupling n Cardiac Muscle The mechanism that couples excitation-an action potential in the plasma membrane of the muscle cell- and contraction of heart muscle
The mechanism that couples excitation – an action potential in the plasma membrane of the muscle cell – and contraction of heart muscle Excitation-Contraction Coupling In Cardiac Muscle
Copyright@ The Me Graw-Hill Companies, Ine, Permission requited for reproduction or display. Passage of an action potential along the o Muscle action potential propagated Muscle plasm membrane transverse tubule opens Transverse tubule nearby voltage-gated DHP Lateral sac Ryanodine Sarcoplasmic reticulum calcium channels. the “ ryanodine receptor,” located on the sarcoplasmIc reticulum and eca· released ADP O Cataken up calcium ions released into the 6 to tro 0 oval from troponin cytosol bind to troponin removes blocking acton tropomyosin Thin The calcium-troponin Troponin complex"pulls"tropomyosin 确动 off the myosin-binding site of actin, thus allowing the O Cross-bridge moves ATP) binding of the cross-bridge followed by its flexing to Thick slide the actin filament Excitation-contraction coupling in skeletal muscle
Passage of an action potential along the transverse tubule opens nearby voltage-gated calcium channels, the “ryanodine receptor,” located on the sarcoplasmic reticulum, and calcium ions released into the cytosol bind to troponin. The calcium-troponin complex “pulls” tropomyosin off the myosin-binding site of actin, thus allowing the binding of the cross-bridge, followed by its flexing to slide the actin filament. Excitation-contraction coupling in skeletal muscle
Copyright@ The McGraw-Hill Companies, Ine Permission required for reproduction or display. (depolarization of plasma membrane) Calcium ions regulate the Opening of plasma membrane L-type contraction of cardiac muscle: Ca<+ channels in T-tubules Flow of Ca2+ into cytosol the entry of extracellular calcium ions causes the Ca2+ binds to Ca2+ receptors (ryanodine receptors) release of calcium from the on the external surface of the sarcoplasmic reticulum sarcoplasmic reticulum (calcium-induced calcium Opening of Ca2+channels intrinsic to these receptors release钙诱导的钙释放],the source of about 95% of the Flow of Ca+into cytosol calcium in the cytosol. T Cytosolic Ca2+ concentration Contraction Excitation-contraction coupling in cardiac muscle
Calcium ions regulate the contraction of cardiac muscle: the entry of extracellular calcium ions causes the release of calcium from the sarcoplasmic reticulum (calcium-induced calcium release [钙诱导的钙释放]), the source of about 95% of the calcium in the cytosol. Excitation-contraction coupling in cardiac muscle
Click here to play the Cardiac EC Coupling Flash animation
Click here to play the Cardiac EC Coupling Flash Animation