Term
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Definition
1. Active relaxation of ventricles
2. Passive relaxation of elastic fibers |
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Term
| Energy requiring steps in diastole |
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Definition
1. SERCA pump actively pumps back Ca into the SR.
2. Causes Ca to disassociate from Troponin C.
3. ATPase function in myosin head causes myosin to detach from actin |
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Term
| Affects of non-elastic stiff heart |
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Definition
Form of diastolic heart failure.
Any increase in blood volume would cause increase in pressure. Treat by using diuretics. |
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Term
| Components of passive diastole |
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Definition
1. Elastic properties of ventricle
2. Titin |
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Term
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Definition
Measure of diastolic function, tests elasticity of the ventricle. Measure change in volume over change in pressure (dV/dP).
When there is loss of elasticity, an increase in volume will result in an increase in pressure, therefore, the heart can store less blood, which in turn impairs O2 delivery.
Occurs in atherosclerosis, fibrosis, and infiltration of the myocardium. |
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Term
| Physiological manifestations of diastolic dysfunction |
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Definition
1. Results in reduced ventricle filling in diastole which results in central and peripheral vascular congestion, such as fluid in lungs.
2. Naturetic peptides are released to reduce Na and water retention, but not enough to restore homeostasis. |
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Term
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Definition
1. Isovolumetric relaxation (active relaxation, reuptake of Ca into SR)
2. Rapid Filling (active portion=ventricular suction)
3. Diastasis (contributes ~5% of blood, blood from SVC and IVC flow passively to ventricle)
4. Atrial systole (accounts for ~15% of filling) |
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Term
| Exercise and ventricular filling |
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Definition
| Increased heart rate cuts down time spent in diastole. To compensate, the ventricles actively relax and create a suction effect that draws more blood into ventricles. |
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Term
| Factors affecting diastolic filling |
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Definition
1. Extracellular matrix
2. Cardiac Myocyte
3. Neurohormones |
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Term
| EC matrix effects on diastolic filling |
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Definition
1. Increased collagen deposition prevents proper relaxation.
2. Increased collagen cross linking and increased collagen type I deposition have same effect. |
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Term
| Collagen balance in myocardium |
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Definition
When collagen regulation skewed, it affects diastolic relaxation of heart.
1. Catecholamines, Aldosterone, and Angiotensin II stimulate collagen production.
2. Collagen degraded by metalloproteinases.
3. Preload
4. Afterload |
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Term
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Definition
1. Macrophage: secrete collagenase and gelatinase to break down matrix
2. T lymphocyte: secretes interferon to inhibit collagen synthesis. |
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Term
| Cardiac myocyte affects of diastolic relaxation |
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Definition
| Cardiac myocyte affected by intrinsic and extrinsic factors. 1. Intrinsic factors: Troponin complex, phospholamban, Titin, Tropomyosin 2. Extrinsic factors: Pericardial inflammation, Restrictive cardiomyopathey, Neurohormonal effects |
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Term
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Definition
| Membrane protein involved in movement of Ca out of SR |
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Term
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Definition
| Troponin C binds to troponin I to inhibit the interaction between the actin and myosin heads.Low calcium levels in diastole result in toponin I binding to actin to inhibit myosin binding |
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Term
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Definition
| Removes the inhibition and activates actomyosin ATPase |
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Term
| Intrinsic myocardial cell causes of diastolic dysfunction |
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Definition
| 1. Defect in sarcolemmal channel. Results in Ca overload in myocyte: Na channels don't close, triggers Ca, Na antiporter that results in increased intracellular Ca. 2. Defects in SR 3. Protein phosphorylation defects (calmodulin, phospholamban, etc). |
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Term
| Extrinsic cardiac myocyte causes of diastolic disorders |
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Definition
| 1. Pericardial disease 2. Restrictive Cardiomyopathy 3. Neurohumeral activation |
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Term
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Definition
| Restrictive pericardium inhibits diastolic relaxation. |
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Term
| Restrictive cardiomyopathy |
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Definition
Deposition of iron, granulomas, and amyloid impair relaxation.
Extrinsic factor of cardiac myocyte, impacts diastolic function. |
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Term
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Definition
| Catecholamines, Endothelin, Angiotensin II, and Aldosterone cause pressure overload, stiffness, ventricular hypertrophy, and collagen deposition. Helps heart in short term by increasing CO, kills in long run. |
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Term
| Effects of beta stimulation |
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Definition
Increases both ionotropy and lusitropy (relaxation).
Ionotropic state regulated by Ca concentration in cytoplasm, increased by beta stimulation.
Lusitropy governed by phosphrylation of phospholamban and Troponin I, which is partially regulated by beta stimulation. |
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