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19 Cards in this Set
- Front
- Back
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1) Substrates and processes to convert them to enter the Krebs cycle |
FFA (resting) - ß-oxidation Glucose (fasting) - glycolysis (Lactate = exercise) |
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2) oxidative phosphorylation |
ADP -> ATP |
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3) ATP transfer and utilization |
Most ATP used by myofibrils for contraction
‘Creatinine Kinase Energy Shuttle’ - phosphate from ATP + creatinine = phosphocreatinine |
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Energy metabolism of heart |
Most of all organs 100 000 beats per day |
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Hypoxia’s effect on heart metabolism |
Cause more anaerobic metabolism - if fully - energy inadequate to sustain ventricular contraction
Therefore if heart not getting any oxygen - cannot pump!! Therefore cannot produce cardiac output |
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Myocardial oxygen extraction at rest |
Near maximum
Therefore a ⬆️ in O2 consumption requires ⬆️ CBF |
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Myocardial oxygen extraction |
9ml/100g/min |
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How heart can meet need for ⬆️ oxygen demand |
⬆️ HR ⬇️ contractility ⬇️ intramyocardial wall stress |
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What does it mean that coronary flow is phasic? |
That CBF is mostly during diastole
As in systole - ⬆️ myocardial P ~ coronary vessels compressed and ⬇️ CBF
In diastole - ⬇️ myocardial P ~ dilated coronary vessels and ⬆️ CBF |
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Means to control coronary resistance |
All to induce vasodilation!! Humeral - NO2 Local metabolism - adenosine, 02 availability Sympathetic innervation
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Hyperemia |
⬆️ BF due to ⬆️ metabolic activity |
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Coronary blood flow resistive effects |
Greater in subendothelial vessels than subepicardial vessels |
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Relationship between oxygen consumption and supply |
During rest: max O2 extraction O2 delivery determined by work of heart ⬆️ flow by ⬆️ O2 delivery ⬆️ flow by ⬇️ R Change in R by local metabolic, funeral and autonomic NS |
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Coronary autoregulation |
Maintain CBF at constant level over range of aortic pressures
⬆️ in perfusion pressure (change in BP) is not accompanied by ⬆️ CBF |
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Coronary autoregulation at rest |
⬆️ BP at rest ~ coronary vasoconstriction ~ ⬆️ R to maintain CBF |
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Coronary autoregulation during exercise |
Exercise ⬆️ BP vastly ~ when BP reaches certain level ~ autoreg stops and vasodilation occurs ~ ⬆️ CBF to meet ⬆️ demand for O2 = coronary flow reserve!!! |
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Coronary flow reserve |
Max ⬆️in blood flow through CA above N resting volume |
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Coronary autoregulation in stenosis |
⬇️ diameter therefore ⬆️ R ~ ⬆️ P even at rest ~ cause coronary flow reserve even at rest (dilation) ~ when exercise coronaries can’t donate anymore ~ cannot ⬆️ perfusion pressure ~ ⬇️ flow |
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Treating ⬇️ coronary blood flow |
Induce vasodilation - ⬆️ perfusion pressure and ⬇️ resistance
Increase diastole duration by ⬇️ HR Decrease work of heart - therefore won’t need such a ⬆️ CBF Remove stenosis - stent |
