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Questions and Answers
What is the primary function of the heart as identified in the cardiovascular system?
What is the primary function of the heart as identified in the cardiovascular system?
Which component of the cardiac conduction system initiates impulses for heart contraction?
Which component of the cardiac conduction system initiates impulses for heart contraction?
What does the RPP (Rate Pressure Product) index represent in cardiac physiology?
What does the RPP (Rate Pressure Product) index represent in cardiac physiology?
Which of the following waves on the ECG corresponds to atrial contraction?
Which of the following waves on the ECG corresponds to atrial contraction?
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What primarily affects the cardiac output (CO) during exercise?
What primarily affects the cardiac output (CO) during exercise?
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How does myocardial oxygen uptake relate to physical exertion?
How does myocardial oxygen uptake relate to physical exertion?
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What does the term 'afterload' refer to in cardiovascular physiology?
What does the term 'afterload' refer to in cardiovascular physiology?
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Which statement regarding heart muscle metabolism is accurate?
Which statement regarding heart muscle metabolism is accurate?
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What is the predicted maximum heart rate formula for determining a person's maximum heart rate?
What is the predicted maximum heart rate formula for determining a person's maximum heart rate?
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What indicates chronotropic incompetence in a subject?
What indicates chronotropic incompetence in a subject?
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Which factor is primarily responsible for stroke volume in terms of the preload?
Which factor is primarily responsible for stroke volume in terms of the preload?
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How is ejection fraction defined?
How is ejection fraction defined?
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During prolonged exercise, what primarily contributes to cardiac output as stroke volume begins to plateau?
During prolonged exercise, what primarily contributes to cardiac output as stroke volume begins to plateau?
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What is considered an abnormal response for systolic blood pressure during exercise?
What is considered an abnormal response for systolic blood pressure during exercise?
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Which statement about peak oxygen uptake (VO2) during upper body exercise is true?
Which statement about peak oxygen uptake (VO2) during upper body exercise is true?
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What physiological change occurs during the Valsalva maneuver?
What physiological change occurs during the Valsalva maneuver?
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What is the recommended action if a subject experiences angina during exercise?
What is the recommended action if a subject experiences angina during exercise?
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Which phenomenon describes the increase in heart rate that can occur during prolonged exercise?
Which phenomenon describes the increase in heart rate that can occur during prolonged exercise?
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What defines a typical response of diastolic blood pressure during graded exercise?
What defines a typical response of diastolic blood pressure during graded exercise?
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What physiological consequence might occur if stroke volume decreases during static exercise?
What physiological consequence might occur if stroke volume decreases during static exercise?
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In the context of heart function, what does the term 'afterload' refer to?
In the context of heart function, what does the term 'afterload' refer to?
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What is a common result of beta blocker therapy in cardiac patients?
What is a common result of beta blocker therapy in cardiac patients?
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Study Notes
Cardiovascular System During Exercise
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Heart Function:
- The heart acts as a pump, composed of epicardium (outer), myocardium (middle), and endocardium (inner).
- Utilizes actin/myosin sliding filament mechanism and ATP for contraction.
- Intercalated discs enable cells to depolarize as a unit, crucial for coordinated pumping.
- Heart's pumping action is coordinated by an electrical conduction system (SA node, AV node, bundle of His, bundle branches, Purkinje fibers).
- Electrical activity produces a characteristic P-QRS-T pattern on an ECG, reflecting atrial (P wave), ventricular depolarization (QRS complex), and ventricular repolarization (T wave).
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Myocardial Oxygen Uptake (MVO2):
- MVO2 is determined by myocardial tension, contractility, and heart rate.
- Rate Pressure Product (RPP) is an index of relative cardiac work (HR x SBP).
- RPP monitoring assists in identifying reproducible angina patterns.
- Exercise increases coronary blood flow 4-6 fold, due to increased metabolism.
- The heart receives 200-250ml blood/minute (5% of resting cardiac output).
- Coronary flow is higher during diastole than systole, important for exercise and cardiac health.
- The heart is primarily aerobic but has a limited anaerobic capability.
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Cardiac Output (CO):
- CO = Stroke Volume (SV) x Heart Rate (HR)
- Stroke Volume is calculated as end-diastolic volume (EDV) minus end-systolic volume (ESV) and depends on preload and afterload.
- Preload is the load on the ventricle at end diastole (EDV).
- Afterload is the mechanical load on the ventricle during ejection (aortic pressure).
- Heart rate is highly influenced by sympathetic/parasympathetic nervous systems and hormones like catecholamines.
- Ejection Fraction (EF) is a global measure of heart efficiency (SV/EDV).
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Heart Rate (HR) and Exercise:
- Maximal heart rate is predicted as 220 minus age +/- 10 bpm.
- Aerobic fitness levels influence maximum HR.
- Heart rate typically increases linearly with exercise intensity. HR increase of 10 +/- 2 bpm per MET is normal.
- An inadequate increase in HR with exercise intensity is concerning.
- Recovery heart rate should decrease by 10 bpm within 1 minute post-exercise.
- Chronotropic incompetence is a decreased heart rate response to exercise (more than 2 standard deviations below predicted max HR).
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Stroke Volume (SV):
- SV correlates with increased venous return (preload), contractility, and reduced afterload.
- SV is influenced by venous return, diastolic filling pressure, blood volume, and systemic blood pressure.
- SV is normally lower in females and smaller individuals.
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Ejection Fraction (EF):
- EF is a measure of LV ejection efficiency (SV/EDV).
- A normal EF is approximately 50%, with lower values indicative of heart failure.
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Arterial Blood Pressure:
- Normal resting blood pressure is typically 100-139/60-89 mmHg.
- Blood pressure generally increases with age.
- Elevated blood pressure (hypertension) stages and hypotension will be mentioned.
- Systolic blood pressure might plateau or remain steady during steady state exercise.
- Exercise-induced hypotension (SBP fails to rise, falls by >10mmHg)) is a concern for MI.
- Diastolic blood pressure typically doesn't change or decreases during graded exercise.
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Exercise Types (Dynamic vs. Static):
- Dynamic exercise involves continuous movement; SV and EDV increase, and afterload decreases.
- Static exercise (isometric contractions) has decreased SV, increased afterload, and increased DBP.
- Valsalva maneuver (forced exhalation against a closed glottis) increases BP and workload on heart.
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Myocardial Ischemia during Exercise:
- Ischemia is a mismatch of oxygen supply and demand due to increasing exercise intensity.
- Signs of ischemia (angina) during exercise should be addressed promptly.
- Static exercise might increase myocardial oxygen demand through the Valsalva maneuver.
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Drug Therapy and Exercise:
- Beta-blockers, diuretics, and anti-coagulants frequently used in treatment of cardiovascular issues.
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Guidelines for Independent Exercise:
- Individuals with heart issues should be assessed for suitability for independent exercise. Considerations are functional aerobic capacity, hemodynamic response, symptom stability, knowledge of management, & appropriate supervision.
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Description
This quiz focuses on the heart's function and its adaptation during exercise. It covers the structure of the heart, electrical conduction system, and myocardial oxygen uptake. Test your knowledge on important concepts such as the Rate Pressure Product and its role in cardiac function.
