Term
| what is the cardiac cycle divided into? |
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Definition
| 2 cycles: systole and diastole |
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Term
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Definition
| the period of time when the heart is contracting, about .27 sec (half the length of diastole) which is .5 isometric contraction (short - both mitral and aortic are closed), and .22 sec ejection |
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Term
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Definition
| the time, .53 sec, when the heart is relaxing which is devided into filling (.41 sec) and atrial systole (during ventricular diastole, .11 sec) |
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Term
| what is the ejection fraction? |
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Definition
| ejection fraction (Ef) is the fraction of the end-diastolic volume that is ejected with each beat - that is, it is stroke volume (SV) divided by end-diastolic volume (EDV) - usually 50-60% of end diastolic volume |
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Term
| how does the heart relax? |
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Definition
| passively, due to low (possibly negative in high heart rates) pressure (not generated by the venous system, but generated instrinsically) |
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Term
| how do skeletal and cardiac muscles differ in terms of response to stimulus? |
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Definition
| skeletal muscle contracts upon stimulation, and if stimulation is removed it will remain in that position. with cardiac muscle, as soon as the stimulus is removed, it will return to its original position (this is how the structure of the heart re-expands - not by venous pressure) |
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Term
| what is blood volume like in the heart during late diastole? |
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Definition
| ventricles are almost full (~150 mL) |
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Term
| what is blood volume like in the heart during atrial systole? |
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Definition
| ventricular volume increases slightly due to "topping off" from atrium. this is not highly critical, except if pts with atrial fibrillation are trying to run a race or something |
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Term
| what is blood volume like in the heart during isometric contraction right after atrial systole? |
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Definition
| this is the beginning of systole, where there is no change in volume b/c both the aortic and mitral valve are closed (lub is the sound of them closing) |
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Term
| what is blood volume like in the heart during the ejection phase? |
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Definition
| ventricular volume declines rapidly when the aortic valve opens |
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Term
| what is blood volume like in the heart during the reduced ejection phase? |
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Definition
| the ventricle begins to relax (due to repolarization of myocytes) when pressure in the aorta < ventricular pressure, so the aortic valve closes, and the mitral valve is still closed (dup sound is aortic backflow hitting the semilunar valves as they slam shut) - and there is another period of isovolumetric relaxation |
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Term
| what is blood volume like in the heart during the rapid filling phase? |
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Definition
| the pressure in the ventricle is less than atrial pressure, and blood flows from the atrium to the ventricle - the beginning of diastole |
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Term
| what is end diastolic volume usually? |
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Definition
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Term
| what is stroke volume usually? |
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Definition
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Term
| what is residual volume usually? |
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Definition
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Term
| what is the basic pattern in the wigger diagram? |
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Definition
| electrical signal, contraction, and pressure change |
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Term
| what is happening in terms of the aortic valve and pressure in diastole? |
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Definition
| the aortic valve is close and aortic pressure is dropping |
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Term
| what causes the mitral valve to open in late diastole? what happens when it opens? |
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Definition
| the atrial pressure exceeds the intraventricular pressure by about 1 mm Hg. when the mitral valve opens, the ventricle fills |
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Term
| what is the EKG P wave during late diastole? |
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Definition
| depolarization of the atria, which "tops off" the ventricle (sound of this is the 4th heart sound) |
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Term
| what is the "a wave" during diastole? |
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Definition
| an increase in atrial pressure that occurs with atrial systole |
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Term
| what happens at the beginning of systole in terms of valves? what is the pressure like? |
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Definition
| the mitral and aortic valves are both closed, this is the period of isovolumetric contraction of the ventricle. at this point interventricular pressure is rising quickly |
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Term
| what signals the end of diastole? |
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Definition
| the R wave signals depolarization of the ventricle, after which tension begins to increase in the ventricular wall and the mitral valve closes -> first heart sound (beginning of systole) |
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Term
| what marks the beginning of systole? |
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Definition
| isovolumetric contraction, where the mitral and aortic valve remain close until the interventricular pressure exceeds aortic pressure and the aortic valve opens -> rapid ejection of blood. |
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Term
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Definition
| the increase in atrial pressure with isovolumetric contraction |
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Term
| what does the T wave indicate during mechanical systole? |
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Definition
| that the repolarization of the ventricles is complete |
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Term
| at the end of systole, with the further relaxation of ventricle what happens? |
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Definition
| the aortic valve closes, and initially blood moves backwards as recoil, creating a notch in the aortic pressure curve. vibration from this causes the 2nd heart sound - and the beginning of diastole |
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Term
| when is the 3rd heart sound heard? |
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Definition
| during rapid movement of the blood from the atria to the venticle (once intraventricular pressure drops below atrial and the mitral valve opens) |
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Term
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Definition
| a decrease in atrial pressure during the rapid ejection phase of systole, and it's lowest point correlates with the peak ejection of blood from the aorta |
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Term
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Definition
| the increase in atrial pressure as the atria fill with blood |
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Term
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Definition
| the decrease in atrial pressure as the blood moves from the atria to the ventricles |
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