Podcast
Questions and Answers
What is the primary factor determining preload in the heart?
What is the primary factor determining preload in the heart?
- Venous vascular volume (correct)
- Diastolic relaxation
- Arterial blood pressure
- Ventricular contraction
According to the Frank-Starling law, what is the relationship between the volume of blood in the heart and the force of contraction?
According to the Frank-Starling law, what is the relationship between the volume of blood in the heart and the force of contraction?
- Variable relationship
- Direct relationship (correct)
- Inverse relationship
- No correlation
What is the term for the pressure or tension work of the heart?
What is the term for the pressure or tension work of the heart?
- Afterload (correct)
- Preload
- Contractility
- Constriction
What is the maximum force of contraction achieved when muscle fibers are stretched to?
What is the maximum force of contraction achieved when muscle fibers are stretched to?
Which of the following can decrease preload?
Which of the following can decrease preload?
What is the primary cause of increased afterload in the right ventricle?
What is the primary cause of increased afterload in the right ventricle?
What is the term for the force that the contracting heart must generate to eject blood from the filled heart?
What is the term for the force that the contracting heart must generate to eject blood from the filled heart?
Why may the failing or dilated heart not respond to increased filling?
Why may the failing or dilated heart not respond to increased filling?
What is the primary component of afterload that affects cardiac output?
What is the primary component of afterload that affects cardiac output?
Which of the following does not increase contractility of the heart?
Which of the following does not increase contractility of the heart?
What is the primary difference between primary and secondary hypertension?
What is the primary difference between primary and secondary hypertension?
What is the relationship between systemic vascular resistance and ventricular oxygen consumption?
What is the relationship between systemic vascular resistance and ventricular oxygen consumption?
Which of the following is NOT a target organ for hypertension?
Which of the following is NOT a target organ for hypertension?
What is the effect of chronic hypertension on systemic blood vessels?
What is the effect of chronic hypertension on systemic blood vessels?
Which of the following is a negative inotrope that decreases contractility of the heart?
Which of the following is a negative inotrope that decreases contractility of the heart?
What is the definition of malignant hypertension?
What is the definition of malignant hypertension?
What is the primary factor that determines cardiac output?
What is the primary factor that determines cardiac output?
What is the chief cause of isolated systolic hypertension (ISH) in the elderly?
What is the chief cause of isolated systolic hypertension (ISH) in the elderly?
Which of the following increases cardiac output by increasing stroke volume?
Which of the following increases cardiac output by increasing stroke volume?
What is the relationship between afterload and intra-ventricular pressure?
What is the relationship between afterload and intra-ventricular pressure?
What is the effect of increased cardiac output on blood pressure?
What is the effect of increased cardiac output on blood pressure?
Which of the following is an example of a factor that affects cardiac output by modifying contractility?
Which of the following is an example of a factor that affects cardiac output by modifying contractility?
What is the effect of hypertension on the eyes?
What is the effect of hypertension on the eyes?
What is the term for the damage caused to organs due to chronic hypertension?
What is the term for the damage caused to organs due to chronic hypertension?
What is the primary determinant of cardiac output according to the Frank-Starling law?
What is the primary determinant of cardiac output according to the Frank-Starling law?
Which of the following increases preload?
Which of the following increases preload?
What is the formula for calculating cardiac output?
What is the formula for calculating cardiac output?
What is the primary factor affecting contractility of the heart?
What is the primary factor affecting contractility of the heart?
What is the normal range of cardiac output in liters per minute?
What is the normal range of cardiac output in liters per minute?
Which of the following increases right ventricular afterload?
Which of the following increases right ventricular afterload?
What is the term for the amount of blood ejected from the heart with each beat?
What is the term for the amount of blood ejected from the heart with each beat?
What is the term for the resistance to ejection of blood from the heart?
What is the term for the resistance to ejection of blood from the heart?
What is the main difference between primary and secondary hypertension?
What is the main difference between primary and secondary hypertension?
Which of the following best describes the Frank-Starling law?
Which of the following best describes the Frank-Starling law?
What is the primary cause of increased afterload in the right ventricle?
What is the primary cause of increased afterload in the right ventricle?
Which of the following factors can increase cardiac output?
Which of the following factors can increase cardiac output?
What is the term for the force that the contracting heart must generate to eject blood from the filled heart?
What is the term for the force that the contracting heart must generate to eject blood from the filled heart?
What is the main consequence of sustained hypertension?
What is the main consequence of sustained hypertension?
What is the term for the pressure or tension work of the heart?
What is the term for the pressure or tension work of the heart?
Which of the following is a factor that can decrease cardiac output?
Which of the following is a factor that can decrease cardiac output?
Study Notes
Cardiac Output and Blood Pressure
- Cardiac output (CO) is the amount of blood the heart ejects in a minute, ranging from 4.2 to 8 Liters.
- CO varies with activity, age, and gender.
- CO depends on stroke volume (SV) and heart rate (HR).
Factors Affecting Cardiac Output
- Preload (or filling of the ventricles): determined by venous return to the heart and the accompanying stretch of muscle fibers.
- Afterload (or resistance to ejection of blood from the heart): determined by systemic vascular resistance (SVR).
- Contractility (intrinsic ability of the heart muscle to contract): determined by biochemical and biophysical properties governing actin and myosin interactions.
Preload and Afterload
- Preload represents the volume work of the heart, imposed before the contraction begins.
- Afterload represents the pressure or tension work of the heart, generated to move blood into the aorta.
Contractility and Inotropes
- Contractility refers to the ability of the heart to change its force of contraction without changing its resting length.
- Positive inotropes (e.g., sympathetic stimulation, dopamine, epinephrine, norepinephrine) increase contractility.
- Negative inotropes (e.g., beta blockers, hypoxia, alcohol, glucose, inflammatory mediators) decrease contractility.
Blood Pressure and Hypertension
- Blood pressure (BP) is determined by cardiac output and systemic vascular resistance.
- Hypertension is a sustained elevation of arterial blood pressure, diagnosed when average BP measurements are 140/90 mmHg or higher.
- Types of hypertension: primary (essential or idiopathic), secondary (caused by systemic disease), and isolated (e.g., systolic hypertension).
Secondary Hypertension
- Caused by systemic disease processes that raise peripheral vascular resistance (PVR) or cardiac output.
- If the cause is identified and removed before permanent structural damage occurs, BP can return to normal.
Complications of Hypertension
- Chronic hypertension damages systemic blood vessels, leading to vascular remodeling and eventual organ dysfunction.
- Target organs affected: kidney, brain, heart, extremities, and eyes.
- Complications: left ventricular hypertrophy (LVH), heart failure, coronary artery disease (CAD), myocardial infarction (MI), stroke, and renal failure.
Isolated Systolic Hypertension and Malignant Hypertension
- Isolated systolic hypertension (ISH) can be caused by increased cardiac output, aortic valve dysfunction, thyroid storm, or beriberi (thiamine deficiency).
- Malignant hypertension is a rapidly progressive form, characterized by diastolic pressure above 140 mmHg, leading to encephalopathy, cerebral edema, and loss of consciousness.
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Description
This quiz covers the concept of afterload in cardiovascular physiology, its relation to systemic vascular resistance, and its effect on cardiac output and ventricular oxygen consumption.
