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
Sarcolemma( ATP)NCX ATP Ca 2Na C Myofilaments NCX ICal, 3Na(Em 三 Contraction Zma、、PCP
Cardiac cycle(心动周期) The cardiac events that occur from beginning of one heartbeat to the beginning of the next are called the cardiac cycle
Cardiac cycle（心动周期） • The cardiac events that occur from beginning of one heartbeat to the beginning of the next are called the cardiac cycle
What happens in the heart during each cardiac cycle? Pressure Volume Valves Blood flow
• Pressure • Volume • Valves • Blood flow What happens in the heart during each cardiac cycle?
(a) systole Isovolumetric ventricular contraction Ventricular ejectio Systole: ventricles contracting Aortic and (b) Diastole Copyrighte~@ Companies, Ine.Permission required tor reproduction or dsplay. lumntric ventricutar retaration Bood flows into ventricles Atrial contraction reared rElaxed Diastole: ventricles relaxed Open alves Cansed closed
Systole: ventricles contracting Diastole: ventricles relaxed
Mechanical Events of the cardiac Cycle Click here to play the Mechanical Events of the Cardiac Cycle Flash Animation
Click here to play the Mechanical Events of the Cardiac Cycle Flash Animation Mechanical Events of the Cardiac Cycle