Term
| What are the events that are typically measured during the cardiac cycle? |
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Definition
-aortic pressure
-let ventricular pressure
-left atrial pressure
-aortic blood flow
-left ventricular volume
-heart sounds
-venous pressure
-electrocardiogram |
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Term
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Definition
| The electrical and mechanical events that occur during one complete sequence of contraction and relaxation by the heart |
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Term
| T/F. The timing of events varies between the left and right sides of the heart. |
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Definition
| False. The timing of events is very similar in both the left and right sides of the heart. |
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Term
| What are the three phases that ventricular systole can be subdivided into? |
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Definition
-Isovolumic (isovolumetric) contraction
-Rapid ejection
-Reduced ejection |
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Term
| What are the 4 subphases of ventricular diastole? |
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Definition
-Isovolumic (isovolumetric relaxation)
-rapid ventricular filling
-reduced ventricular filling (diastasis)
-atrial systole |
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Term
| T/F. During physical activity atrial contraction has a larger contribution to ventricular volume. |
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Definition
| True. This is due to the increase in heart rate, b/c there is less time for passive filling. |
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Term
| What signals to increase the force of atrial contraction? |
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Definition
| The sympathetic nervous system. |
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Term
| When are blood volumes of the ventricle the greatest? |
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Definition
| At the end of atrial systole and ventricular diastole--this is referred to as end-diastolic volume (EDV) |
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Term
| On an ECG what does ventricular contraction coincide with? |
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Definition
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Term
| When do the AV valves close? |
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Definition
| When the increase in intraventricular pressure exceeds atrial pressure. |
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Term
| What causes the first heart sound? |
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Definition
| S1 is caused by clsure of the AV valeves. |
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Term
| When do the aortic and pulmonary valves open? |
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Definition
| Aortic and pulmonary valves open when the pressure in the ventricles exceeds the pressure within the aorta and pulmonary artery. |
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Term
| What four things take place during the paid ejections phase? |
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Definition
-Ventricular pressures continue to rise
-Pressure within the aorta and pulmonary arteries increase
-Blood flow from the ventricles into the aorta and pulmonary arteries peaks
-Ventricular volume decreases |
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Term
| When is most of the stroke volume ejected from the heart? |
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Definition
| During rapid ejection about 70% of stroke volume is ejected from the heart. |
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Term
| Why does atrial volume increase during rapid ejection? |
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Definition
| Atrial volume increases because venous return in ongoing and the AV valves are closed |
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Term
| T/F Relaxation of the ventricles is signaled by repolarization. |
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Definition
| False. Repolarization has nothing to do with relaxation |
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Term
| What signals the start of diastole? |
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Definition
| Closure of the aortic and pulmonary valves signals the start of diastole |
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Term
| What causes the second heart sound, S2? |
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Definition
| Closing of the semilunar valve. |
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Term
| What happens to the pressure of the ventricles during isovolumic (isovolumetric) relaxation? |
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Definition
| It rapidly declines, b/c the ventricles relax |
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Term
| When do the aortic and pulmonary valves close? |
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Definition
| When blood flow through the aortic and pulmonary valves slows and then reverses direction. |
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Term
| What is the dicrotic notch or incisura? What does it correspond to? |
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Definition
| The dicrotic notch or incisura isslight upward deflection in the aortic and pulmonary artery pressure traces that momentarily interrupt the decline in blood pressure. |
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Term
| How can the end of ventricular systole be observed? |
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Definition
| By the dicrotic notch or incisura in aortic or pulmonary artery pressure traces. |
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Term
| T/F. Blood enters the ventricles during isolvolumic relaxation. |
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Definition
| False. The AV and semilunar valves are closed so no blood can enter the ventricles during isovolumic relaxation. |
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Term
| Whey is ventricular filling rapid during the rapid filling phase? |
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Definition
-B/c venous return has filled the atria prior to the opening of the AV valves
-the resistance to flow through the AV valves is very low |
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Term
| What stage follows the rapid filling stage? What are its characteristics? |
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Definition
The reduced filling stage. During reduced filling the rate of passive filling slows and reaches a plateau, due to the ventricles filling and becoming less compliant.
-Aortic pressure and pulmonary artery pressure continue to fall as blood flows into the systemic and pulmonary circulations.
-Atrial systole tops off ventricular volume |
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Term
| What is the first heart sound? What is it associated with the onset of (systole or diastole)? |
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Definition
| The first heart sound is the closing of the AV valves. It is associated with the onset of systole. |
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Term
| If the first heart sound is the closing of the mitral and tricuspid valve why are two sounds not heard? |
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Definition
| Closure of the mitral valve usually occurs just prior to closure of the tricuspid valve, however the two valves close within about 0.01 sec of each other so two separate sounds are not distinguishable. |
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Term
| What causes the second heart sound? |
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Definition
| Closure of the semilunar valves at the end of systole. |
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Term
| Which valve closes first during the second heart sound? |
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Definition
| Aortic valve normally closes prior to the pulmonary valve. |
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Term
| What is physiological splitting of the S2? |
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Definition
| The phenomenon that occurs when a person takes a deep breath and closure of the aortic and pulmonary valve can be individually heard. |
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Term
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Definition
| It is heard in early diastole after the opening of the AV valves. It is normal in children, but may be pathological in adults. |
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Term
| When is the fourth heart sound heard? What does it coincide with? |
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Definition
| The fourth heart sound is heard in late diastole and coincides with contraction of the atria. It is more common in older people and can be an indicator of ventricular stiffness. |
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Term
| What causes a heart murmur? |
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Definition
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Term
| What conditions can generate a murmur (5)? |
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Definition
-partial obstruction (stenosis)
-increased blood flow through normal structures
-regurgitation through an incompetent valve
-ejection into a dilated chamber
-abnormal shunting of blood from one chamber to a lower pressure chamber (ex. septal defect) |
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Term
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Definition
| Sounds created by turbulent blood flow in blood vessels. |
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Term
| How can pressure changes of in the right atrium be observed by a clinician? |
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Definition
| By observing the distention of the internal jugular vein caused by the retrograde flow of blood. |
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Term
| What waves are associated with the venous pulse curve obtained from the jugular vein? |
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Definition
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Term
| What produces the a wave of venous pulse? |
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Definition
| The a wave is charted as an upward deflection and is produced by atrial systole. Disruption of venous flow into the right atrium can also contribue to the a wave. |
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Term
| What events produce the c wave of venous pulse? |
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Definition
| Produced when the tricuspid valves close and bulge into the right atrium at the onset of isovolumetric ventricular contraction. |
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Term
| How is the V wave charted and what events are associated with it in venous pulse? |
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Definition
| The v wave (venous collection)- is charted as an upward deflection and is caused by filling of the right atrium behind the closed tricuspid valve. When the tricuspid valve opens after ventricular systole the wave drops as blood in the atrium moves into the ventricle. |
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Term
| What effect does an increased heart rate have on the percentage of time the heart spends in diastole/systole? |
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Definition
| At a resting heart rate (75 bpm) the heart spends more time in diastole then systole. At a heart rate of 200 bpm the time in diastole is equal to the time in systole. |
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Term
| What is tachycardia and what are two clinical implications of tachycardia? |
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Definition
Tachycardia is increased heart rate and leads to a reduced duration of diastole.
This means:
-there is less time for venous return which reduces cardiac input
-perfusion of the myocardium is less effective |
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