Cardiovascular Physiology: Afterload and Cardiac Output
40 Questions
11 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

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?

  • Variable relationship
  • Direct relationship (correct)
  • Inverse relationship
  • No correlation

    • 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?

    <p>2.5 times their resting length</p> Signup and view all the answers

    Which of the following can decrease preload?

    <p>Obstruction to blood returning to the heart</p> Signup and view all the answers

    What is the primary cause of increased afterload in the right ventricle?

    <p>Increased pulmonary vascular resistance</p> Signup and view all the answers

    What is the term for the force that the contracting heart must generate to eject blood from the filled heart?

    <p>Afterload</p> Signup and view all the answers

    Why may the failing or dilated heart not respond to increased filling?

    <p>Because its fibers are already lengthened maximally</p> Signup and view all the answers

    What is the primary component of afterload that affects cardiac output?

    <p>Systemic vascular resistance</p> Signup and view all the answers

    Which of the following does not increase contractility of the heart?

    <p>Beta blockers</p> Signup and view all the answers

    What is the primary difference between primary and secondary hypertension?

    <p>Primary hypertension is caused by a systemic disease process, while secondary hypertension is not.</p> Signup and view all the answers

    What is the relationship between systemic vascular resistance and ventricular oxygen consumption?

    <p>Directly proportional</p> Signup and view all the answers

    Which of the following is NOT a target organ for hypertension?

    <p>Lungs</p> Signup and view all the answers

    What is the effect of chronic hypertension on systemic blood vessels?

    <p>It causes hypertrophy and hyperplasia of the tunica intima and media.</p> Signup and view all the answers

    Which of the following is a negative inotrope that decreases contractility of the heart?

    <p>Hypoxia</p> Signup and view all the answers

    What is the definition of malignant hypertension?

    <p>A type of hypertension that is rapid and progressive, with diastolic pressure usually above 140 mm Hg.</p> Signup and view all the answers

    What is the primary factor that determines cardiac output?

    <p>Stroke volume</p> Signup and view all the answers

    What is the chief cause of isolated systolic hypertension (ISH) in the elderly?

    <p>Rigidity of proximal large arteries.</p> Signup and view all the answers

    Which of the following increases cardiac output by increasing stroke volume?

    <p>Increase in contractility</p> Signup and view all the answers

    What is the relationship between afterload and intra-ventricular pressure?

    <p>Directly proportional</p> Signup and view all the answers

    What is the effect of increased cardiac output on blood pressure?

    <p>It increases blood pressure.</p> Signup and view all the answers

    Which of the following is an example of a factor that affects cardiac output by modifying contractility?

    <p>Sympathetic stimulation</p> Signup and view all the answers

    What is the effect of hypertension on the eyes?

    <p>It causes changes in the vascular bed, noted by viewing the arterioles of the retina.</p> Signup and view all the answers

    What is the term for the damage caused to organs due to chronic hypertension?

    <p>Target organ damage.</p> Signup and view all the answers

    What is the primary determinant of cardiac output according to the Frank-Starling law?

    <p>End-diastolic volume (EDV)</p> Signup and view all the answers

    Which of the following increases preload?

    <p>Increased venous return</p> Signup and view all the answers

    What is the formula for calculating cardiac output?

    <p>CO = SV x HR</p> Signup and view all the answers

    What is the primary factor affecting contractility of the heart?

    <p>Interaction of actin and myosin filaments</p> Signup and view all the answers

    What is the normal range of cardiac output in liters per minute?

    <p>4.2-8 L/min</p> Signup and view all the answers

    Which of the following increases right ventricular afterload?

    <p>Increase in pulmonary vascular resistance</p> Signup and view all the answers

    What is the term for the amount of blood ejected from the heart with each beat?

    <p>Stroke volume (SV)</p> Signup and view all the answers

    What is the term for the resistance to ejection of blood from the heart?

    <p>Afterload</p> Signup and view all the answers

    What is the main difference between primary and secondary hypertension?

    <p>Primary hypertension affects 90-95% of individuals, whereas secondary hypertension affects the remaining 5-10%.</p> Signup and view all the answers

    Which of the following best describes the Frank-Starling law?

    <p>The law states that the force of contraction of the heart is directly proportional to the volume of blood in the heart.</p> Signup and view all the answers

    What is the primary cause of increased afterload in the right ventricle?

    <p>Increased peripheral vascular resistance.</p> Signup and view all the answers

    Which of the following factors can increase cardiac output?

    <p>Increased heart rate.</p> Signup and view all the answers

    What is the term for the force that the contracting heart must generate to eject blood from the filled heart?

    <p>Afterload.</p> Signup and view all the answers

    What is the main consequence of sustained hypertension?

    <p>Target organ damage.</p> Signup and view all the answers

    What is the term for the pressure or tension work of the heart?

    <p>Cardiac work.</p> Signup and view all the answers

    Which of the following is a factor that can decrease cardiac output?

    <p>Increased peripheral vascular resistance.</p> Signup and view all the answers

    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.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    NU608 Cardiac Output PDF

    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.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser