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Questions and Answers
What is the formula to calculate stroke volume?
Which factor influences preload?
What happens to stroke volume when contractility decreases?
Which factor influences stroke volume by increasing the force of muscle contraction?
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What does afterload refer to in the context of cardiac output?
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Which nervous system influences heart rate to slow down?
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During which phase of the cardiac cycle do the ventricles contract and build up pressure to open the semilunar valves?
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What is the approximate amount of blood that pumps from each ventricle during ventricular ejection?
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Which valve must be closed during isovolumetric relaxation?
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What factor contributes to passive filling of the ventricles?
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Which formula is used to calculate Cardiac Output (CO)?
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What does Stroke Volume (SV) represent in the context of Cardiac Output?
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Which node is slower than the SA node and is located posterior and medial to the tricuspid valve?
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What is the role of a pacemaker in case of SA node misfiring?
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What happens to the heart rate if the AV node fails to function properly?
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Which type of fibrillation is life-threatening and manifests as chaotic activity on an EKG tracing?
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What is the clinical significance of a T wave in an EKG reading?
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Which node is responsible for picking up the pace if both the SA node and the AV node fail?
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Study Notes
Cardiac Output and Stroke Volume
- The formula to calculate stroke volume is: SV = EDV - ESV, where EDV is end-diastolic volume and ESV is end-systolic volume.
- Preload is influenced by the volume of blood in the ventricles, also known as end-diastolic volume.
- When contractility decreases, stroke volume decreases.
- Contractility is increased by sympathetic stimulation, which increases the force of muscle contraction and thus influences stroke volume.
Cardiac Cycle and Valves
- During the systolic phase of the cardiac cycle, the ventricles contract and build up pressure to open the semilunar valves.
- Approximately 70 ml of blood is pumped from each ventricle during ventricular ejection.
- The mitral valve must be closed during isovolumetric relaxation.
Cardiac Output and Filling
- The formula to calculate Cardiac Output (CO) is: CO = HR x SV, where HR is heart rate and SV is stroke volume.
- Stroke Volume (SV) represents the amount of blood pumped by the heart per beat.
- Gravity and suction of the ventricles contribute to passive filling of the ventricles.
Electroconduction and Pacemakers
- The AV node is slower than the SA node and is located posterior and medial to the tricuspid valve.
- A pacemaker takes over the pacing function if the SA node misfires or fails.
- If the AV node fails to function properly, the heart rate slows down.
- The AV node can take over the pacing function if both the SA node and the AV node fail.
Arrhythmias and EKG
- Ventricular fibrillation is a life-threatening arrhythmia that manifests as chaotic activity on an EKG tracing.
- A T wave in an EKG reading indicates ventricular repolarization, which is important for diagnosing cardiac conditions.
- The Bundle of His is responsible for picking up the pace if both the SA node and the AV node fail.
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Description
This quiz covers the concept of cardiac output, stroke volume, and factors that influence heart rate. Topics include calculating stroke volume, understanding cardiac output, and the role of the sympathetic and parasympathetic nervous systems in regulating heart rate.
