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11 Cards in this Set
- Front
- Back
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What are the steps of the cardiac cycle?
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1. Atrial systole
2. Isovolumetric ventricular contraction 3. Rapid ventricular ejection 4. Reduced ventricular ejection 5. Isovolumetric ventricular relaxation 6. Rapid ventricular filling 7. Reduced ventricular filling 8. Repeat |
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What is Isovolumetric contraction?
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Left ventricle is filled with blood from the left atrium and the ventricular muscle is relaxed.
Upon excitation, the ventricle contracts and vent. pressure increases once LV pressure> LA pressure, the mitral valve closes. All valves are then closed and no blood is ejected, but the LV contraction continues and LV pressure increases. |
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What is ventricular ejection?
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When LV pressure> aorta pressure, the aortic valve opens and blood is ejected out of the LV, and into the aorta.
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What is isovolumetric relaxation?
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LV begins to relax and when LV pressure< aorta pressure, the aortic valve closes. All valves are closed at this point, but the ventricle continues to relax.
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What is ventricular filling?
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When LV pressure< LA pressure, the mitral valve opens and the ventricle begins to fill.
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What is the volume of the ventricle before isovolumetric contraction?
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EDV
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What is the width of the pressure volume loop a measurement of?
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SV(stroke volume)
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What is the volume of the ventricle at the end of ventricular ejection?
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ESV
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What is increased preload?
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Increased preload results from increased venous return and causes an increase in EDV. This increase causes an increase in SV(due to Frank Starling relationship) which is reflected as an increased width of the loop.
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What is increased afterload?
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Increased afterload results from an increase in aortic pressure, which leads to a decrease in SV. This decreases the width of the loop.
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What is the result of increased contractility?
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Increased contractility leads to the ventricle developing greater tension during systole and increases the SV.
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