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25 Cards in this Set
- Front
- Back
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What is the Frank-Starling law?
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Force of ejection is proportional to the length of the muscle fibers.
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How is the Frank starling law different in cardiac muscle and skeletal muscle?
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Skeletal muscle operates at optimal length. Excess stretching of the muscle decreases the amount of force.
Cardiac muscle operates at less than optimal length. Excess stretch increases the amount of force. |
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What is the result of contractility and SV on increased calcium?
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Increased contractility; increased SV
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What is the effect of ESV and ventricular pressure by increasing afterload?
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Increased ventricular pressure and decreased ESV, resulting in decreased SV.
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What is the result on EDV and SV by decreasing compliance?
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Decreased EDV and decreased SV.
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What is auxotonic contraction?
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As cardiac muscle shortens during systole, the force and volume ejected decrease.
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What is the velocity index of cardiac contraction? What causes decreased velocity index?
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Measurement of the rate at which ventricular pressure rises during isovlumetric contraction.
Heart failure result in decreased velocity index. |
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What is the external work of the heart?
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Work expended to move blood in the heart (10% of total)
EW= ventricular pressure * stroke volume |
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What is the internal work of the heart?
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Isovolumic contraction, returning the heart back to contractable state.
IW= time spent in isovolumetric contraction * ventricular wall tension |
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What are the normal pressures in the right atria? Left atria? Right ventricle? Left ventricle? Pulmonary artery? Aorta?
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R atria= 0-5
L atria= 1-10 R ventricle= 1-8(diastolic); 15-30 (systolic) L ventricle= 3-12(d); 100-140(s) Pulmonary artery= 5-12(d); 15-30(s) Aorta= 60-90(d); 100-140(s) |
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What values stay the same for left and right ventricles?
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Heart rate
Stroke volume (70mL) Ventricular output |
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What are the two basic mechanisms of regulation of stroke volume?
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Heterometric- length dependent. Frank starling.
Homeometric- length independent. Extrinsic; inotropes. |
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What mechanisms increase contractility in the heart?
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Alteration of preload.
Increased force caused by increased calcium, phosphorylation of kinases. |
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What is the effect of a failing heart on the pressure-volume curve?
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A heart in failure will move the curve down initially. The same amount of pressure will create a smaller stroke volume. Compensation occurs by increasing pressure.
Increased EDV causes more heart failure and pulmonary congestion. |
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How does increased venous return affect cardiac output?
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Increased end-diastolic volume causes a compensatory increase in stroke volume and cardiac output.
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What happens to the volume-pressure curve in diastolic heart failure?
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Decreased compliance causes a greater amount of pressure and decreased volume.
Decreased EDV and compensatory decreased ESV. |
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how does increased afterload affect cardiac output?
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Increased afterload leads to decreased stroke volume and decreased cardiac output, as well as increased EDV.
As EDV rises, preload increases and cardiac output returns to normal. |
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How does increased heart rate (with constant pressure and venous return) affect cardiac output?
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Initial rise in cardiac output, causing decreased EDV. Reduction in EDV causes decreased contractility and SV.
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How does NE release with controlled heart rate and pressure affect cardiac output?
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Increased contractility causes initial increase in stroke volume, leading to decreased EDV. Stroke volume and cardiac output then return to normal, with a decreased EDV.
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What are the effects of aortic stenosis on the pressure volume loop?
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Reduced SV due to increased afterload.
Increased ESV and compensatory EDV. Greater pressure needed to achieve SV. |
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What are the effects of mitral stenosis on the pressure-volume loop?
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Impaired ventricular filling reduces EDV.
Reduced SV. Compensatory decrease in ESV. |
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What are the features of aortic stenois on echo?
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Large wave indicative of increased velocity.
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What are features of mitral stenosis on echo?
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Decreased E wave and increased A wave.
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What are the effects of aortic regurgitation on the pressure-volume loop?
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Backflow from aorta and venous return increase EDV.
No true isovolumetric relaxation or contraction. |
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What are the effects of mitral regurgitation on the pressure-volume loop?
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Decreased afterload causes decreased ESV.
No true isovolumetric relaxation or contraction. Increased EDV from backflow from the ventricle. |
