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Questions and Answers
Which layer of the heart consists of the main muscle layer?
Which layer of the heart consists of the main muscle layer?
Where are the coronary arteries located in relation to the heart's walls?
Where are the coronary arteries located in relation to the heart's walls?
Which coronary vessel supplies the lateral wall of the left ventricle?
Which coronary vessel supplies the lateral wall of the left ventricle?
What happens to the blood flow in coronary vessels during physical stress?
What happens to the blood flow in coronary vessels during physical stress?
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At what occlusion percentage does resting blood flow become insufficient to meet oxygen demand?
At what occlusion percentage does resting blood flow become insufficient to meet oxygen demand?
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What role does the heart play in supplying blood to the body?
What role does the heart play in supplying blood to the body?
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What is the primary cause of tissue hypoxia in the myocardium during activities like running?
What is the primary cause of tissue hypoxia in the myocardium during activities like running?
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What process may result in complete occlusion of the vessel supplying a specific region of the myocardium?
What process may result in complete occlusion of the vessel supplying a specific region of the myocardium?
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What is the main characteristic of Phase 0 of the fast-response action potential in cardiac cells?
What is the main characteristic of Phase 0 of the fast-response action potential in cardiac cells?
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Which type of action potentials occur in atrial and ventricular myocardial fibers as well as Purkinje fibers?
Which type of action potentials occur in atrial and ventricular myocardial fibers as well as Purkinje fibers?
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What is responsible for the plateau phase in the fast-response action potential?
What is responsible for the plateau phase in the fast-response action potential?
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What triggers the release of a large amount of calcium into the cytosol from the sarcoplasmic reticulum during myocardial contraction?
What triggers the release of a large amount of calcium into the cytosol from the sarcoplasmic reticulum during myocardial contraction?
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During which phase is ventricular contraction sustained throughout the action potential?
During which phase is ventricular contraction sustained throughout the action potential?
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Which ion is mainly responsible for repolarization during Phase 3 of the fast-response action potential?
Which ion is mainly responsible for repolarization during Phase 3 of the fast-response action potential?
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'Restoration of ionic concentrations' during Phase 4 is primarily mediated by which cellular mechanism?
'Restoration of ionic concentrations' during Phase 4 is primarily mediated by which cellular mechanism?
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'ATP-driven Ca++ Pump' mentioned in Phase 4 is responsible for which physiological process?
'ATP-driven Ca++ Pump' mentioned in Phase 4 is responsible for which physiological process?
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Study Notes
Heart Structure and Function
- The myocardium consists of the main muscle layer of the heart.
- The coronary arteries are located in the epicardium, the outermost layer of the heart's walls.
- The obtuse marginal branch of the left circumflex coronary artery supplies the lateral wall of the left ventricle.
Blood Flow and Oxygen Demand
- During physical stress, blood flow in coronary vessels increases to meet the increased oxygen demand.
- If the coronary artery is occluded by more than 70%, resting blood flow becomes insufficient to meet oxygen demand.
- The heart plays a crucial role in supplying blood to the body, and any disruption in blood flow can lead to tissue hypoxia.
Tissue Hypoxia and Coronary Occlusion
- The primary cause of tissue hypoxia in the myocardium during activities like running is the inability of the coronary circulation to meet the increased oxygen demand.
- Atherosclerosis, a process of plaque buildup, may result in complete occlusion of the vessel supplying a specific region of the myocardium.
Action Potentials in Cardiac Cells
- The main characteristic of Phase 0 of the fast-response action potential in cardiac cells is a rapid depolarization due to the influx of sodium ions.
- Fast-response action potentials occur in atrial and ventricular myocardial fibers as well as Purkinje fibers.
- The plateau phase in the fast-response action potential is primarily maintained by the influx of calcium ions.
- The release of a large amount of calcium into the cytosol from the sarcoplasmic reticulum during myocardial contraction is triggered by the depolarization of the sarcolemma.
- Ventricular contraction is sustained throughout the action potential during Phase 2.
- Potassium ions are mainly responsible for repolarization during Phase 3 of the fast-response action potential.
- 'Restoration of ionic concentrations' during Phase 4 is primarily mediated by the Na+/K+ ATPase pump.
- The 'ATP-driven Ca++ Pump' is responsible for the reuptake of calcium ions into the sarcoplasmic reticulum during Phase 4.
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Description
Test your knowledge of cardiac action potential and its relation to ECG with this quiz. Topics include heart chambers, myocardial layers, coronary arteries, and coronary anatomy.
