Chapter 12: Cardiovascular Physiology Excitation-Contraction Coupling The mechanism that couples excitation-an action potential in the plasma membrane of the muscle cell-and contraction of heart muscle
Chapter 12: Cardiovascular Physiology The mechanism that couples excitation – an action potential in the plasma membrane of the muscle cell – and contraction of heart muscle Excitation-Contraction Coupling
Figure 9-12 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
Figure 9-12 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
Figure 12-17 Calcium ions regulate the Opening of plasma membrane contraction of cardiac muscle: T-tubules Flow of Ca2+into cytosol the entry of extracellular calcium ions causes the Ca2binds to Ca2receptors release of calcium from the sarcoplasmic reticulum (calcium-induced calcium release),the source of about 95%of the calcium in the Flow of Ca2 into cytosol cytosol. Multiple steps 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), the source of about 95% of the calcium in the cytosol. Figure 12-17 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
Cardiac cycle The cardiac events that occur from beginning of one heartbeat to the beginning of the next are called the cardiac cycle
Cardiac cycle • The cardiac events that occur from beginning of one heartbeat to the beginning of the next are called the cardiac cycle
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
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?
Figure 12-19 (a) Systole: ventricles contracting 道道 Diastole: ventricles relaxed 送腾者
Systole: ventricles contracting Diastole: ventricles relaxed Figure 12-19
Figure 12-20 Summary of events in the left atrium,left ventricle,and aorta during the cardiac cycle
Summary of events in the left atrium, left ventricle, and aorta during the cardiac cycle Figure 12-20