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23 Cards in this Set
- Front
- Back
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What is rapid depolarization?
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At threshold, voltage regulated sodium channels open and the membrane suddenly becomes permeable to Na+. There is a massive influx of Na+ ions and rapid depolarization of the sarcolemma.
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What is the "Plateau"?
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As membrane potential approaches +30mV, Na+ channels close. They remain closed and inactivated until membrane potential reaches -60mV. Sodium channels are closing, and Ca+ channels are opening. In a skeletal muscle fiber, rapid depolarization is immediately followed by rapid depolarization.
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What is Repolarization?
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Slow Ca+ channels begin closing, and slow K+ channels begin opening. K+ ions rush out of the cell resulting in rapid repolarization that restores resting potential.
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After an infarction has occurred, certain enzymes may appear in the blood. What are they/
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lactate dehydrogenase(LDH)
SGOT(serum glutamic oxaloacetic transaminase)(AST) creatine phosphokinase(CPK) troponin CK-MB and Troponin are used most commonly. |
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The cardiac cycle begins with atrial systole, which lasts about 100msec in a resting adult. TRUE/FALSE
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TRUE.
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What is "end diastolic volume"?
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At the end of atrial systole, each ventricle contains the maximum amount of blood that it will hold in this cardiac cycle. That quantity is called end diastolic volume. It is typically about 130ml.
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Ventricular systole lasts about 270msec. TRUE/FALSE
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TRUE.
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What is end systolic volume?
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The amount of blood remaining in the ventricle when the semilunar valve closes is the ESV, and it is about 50ml, about 40% of end diastolic volume.
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What is Dicrotic notch?
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After ventricular systole, blood in the aorta and pulmonary trunk now starts to flow back toward the ventricles and this closes the semilunar valves. Pressure decreases in the aorta and then rises again, causing an aortic bulge.
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What are the 4 heart sounds?
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S1= marks the start of ventricular contraction.
S2= occurs at the beginning of ventricular filling when semilunar valves close. S3= blood flowing into the ventricles S4= atrial contraction. S3/S4= are faint and seldom heard in healthy adults. S3 may be normal in children. |
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What is Stroke volume?
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The amount of blood pumped out of each ventricle during a single beat. (SV=EDV-ESV)
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What is Ejection fraction?
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The percentage of the EDV represented by the SV.
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What is the formula for cardiac output?
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CO=HR X SV
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The cardiac centers of the medulla oblongata contain the autonomic headquarters for cardiac control. TRUE/FALSE
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TRUE.
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What is the effect of acetylcholine on heart rate?
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Acetylcholine, released by parasympathetic neurons opens chemically regulated K+ channels in the cell membrane, dramatically slowing the rate of spontaneous depolarization and also slightly extending the duration of repolarization.
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What is the effect of NE on heart rate?
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NE released by sympathetic neurons binds to beta-1 receptors leading to the opening of sodium-calcium ion channels. This influx of positively charged ions increases the rate of depolarization and shortens the period of repolarization.
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What is Preload?
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The preload is directly proportional to the EDV; The greater the EDV, the larger the preload.
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What is the Frank-Starling principle?
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Increasing the EDV results in a corresponding increase in the stroke volume.
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The drugs isoproteronol, dopamine and dobutamine mimic the action of E and NE by stimulating beta 1 receptors on cardiac muscle cells. TRUE/FALSE
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TRUE.
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Digitalis and related drugs elevate intracellular calcium concentrations. They interfere with the removal of Ca+ from the sarcoplasm of cardiac muscle cells. TRUE/FALSE
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TRUE.
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List some drugs that treat hypertension?
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These drugs have a negative inotropic effect. Beta blocking drugs such as,
propranolol, timolol, metaprolol, atenolol, and labetalol, block beta receptors, alpha receptors or both, and prevent sympathetic stimulation. calcium cjannel blockers such as nifedipine or verapamil also have a negative inotropic effect. |
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What is afterload/
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It is the amount of tension the contracting ventricle must produce to force open the semilunar valve and eject blood.
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Afterload is increased by any factor that restricts blood flow through the arterial system. TRUE/FALSE
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TRUE.
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