Physiology Chapter 14: Cardiac Output Quiz
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Questions and Answers

What is cardiac output?

Volume of blood ejected by each ventricle each minute.

What is cardiac output determined by?

  • Heart rate
  • Stroke volume
  • Both heart rate and stroke volume (correct)
  • None of the above

    • What is stroke volume?

    Blood pumped per beat.

    What is stroke volume determined by?

    <p>All of the above</p> Signup and view all the answers

    What is the Frank-Starling law of the heart?

    <p>Heart pumps what it gets; an increase in diastolic volume increases stroke volume.</p> Signup and view all the answers

    What influences venous return?

    <p>The position of the body (lying down vs standing up).</p> Signup and view all the answers

    What is afterload?

    <p>The resistance that the heart has to pump against</p> Signup and view all the answers

    What does the sympathetic nervous system do to stroke volume?

    <p>It increases stroke volume.</p> Signup and view all the answers

    How is heart rate determined?

    <p>By the balance of parasympathetic and sympathetic influence on the SA node.</p> Signup and view all the answers

    What is ejection fraction of cardiac output?

    <p>Fraction of blood pumped out with each heart beat.</p> Signup and view all the answers

    What does the cardiovascular system consist of?

    <p>All of the above</p> Signup and view all the answers

    How is the flow of blood measured?

    <p>F = P/R</p> Signup and view all the answers

    What are the determinants of resistance in blood flow?

    <p>Blood viscosity, vessel length, and vessel radius.</p> Signup and view all the answers

    What is the relationship between vessel's radius and blood flow?

    <p>A slight change in radius produces a significant change in blood flow.</p> Signup and view all the answers

    What function do arteries serve?

    <p>They provide low resistance due to their large radius and act as a pressure reservoir.</p> Signup and view all the answers

    What is blood pressure?

    <p>The force exerted by blood against a vessel wall.</p> Signup and view all the answers

    What is systolic pressure?

    <p>Maximal arterial pressure.</p> Signup and view all the answers

    What is diastolic pressure?

    <p>Minimum pressure in arteries when blood is draining.</p> Signup and view all the answers

    What is pulse pressure?

    <p>The difference between systolic and diastolic pressure.</p> Signup and view all the answers

    What is Mean Arterial Pressure (MAP)?

    <p>Average pressure driving blood forward into tissues throughout the cardiac cycle.</p> Signup and view all the answers

    What determines MAP?

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

    What type of muscle is found in arterioles?

    <p>Smooth muscle.</p> Signup and view all the answers

    What do arterioles determine?

    <p>The radius of blood vessels.</p> Signup and view all the answers

    What alters the radius of vessels?

    <p>Changes within other organs.</p> Signup and view all the answers

    What is the only steady blood flow?

    <p>To the brain.</p> Signup and view all the answers

    Study Notes

    Cardiac Output

    • Volume of blood ejected by each ventricle per minute.
    • Determined by heart rate (HR) and stroke volume (SV). Equation: CO = HR x SV.

    Stroke Volume

    • Amount of blood pumped per heartbeat, measured in ml/beat.
    • Influenced by:
      • End diastolic volume (EDV): blood volume in ventricles before contraction, indicating venous return.
      • Afterload: resistance the heart must overcome to eject blood.
      • Sympathetic activity: enhances stroke volume.

    Frank-Starling Law

    • The heart pumps according to the amount of blood received; increased diastolic volume leads to increased stroke volume.

    Venous Return

    • Easier when lying down than standing due to gravity effects.
    • Higher venous return when lying down, indicating blood accumulation in the upper body.

    Cardiac Muscle

    • Not at optimal resting length at rest; the muscle stretches as it fills with blood.

    Afterload Impact

    • Increased afterload decreases stroke volume; smaller vessel diameter requires more work from the heart.

    Sympathetic Nervous System

    • Increases stroke volume through enhanced contractility; increases calcium in the sarcoplasmic reticulum, enhancing ventricular contraction strength.

    Heart Rate Determinants

    • Influenced by the balance of sympathetic (increases HR) and parasympathetic (decreases HR) activity on the sinoatrial (SA) node.
    • Parasympathetic tone dominates at rest, slowing the intrinsic heart rate.

    Ejection Fraction

    • Fraction of blood pumped out of the heart with each beat, calculated as SV/EDV x 100.
    • Normal ejection fraction ranges from 50% to 65%.

    Components of Cardiovascular System

    • Comprised of heart, blood, and blood vessels which transport blood.

    Blood Flow Measurement

    • Flow rate (F) determined by the pressure gradient (P) and resistance (R) in vessels: F = P/R.
    • Blood flow is directly proportional to pressure and inversely related to resistance.

    Determinants of Resistance

    • Blood viscosity, vessel length (increases with obesity), and vessel radius (the main determinant).

    Vessel Radius Impact

    • Minor alterations in vessel radius can significantly affect blood flow; resistance is proportional to 1/radius^4.

    Arteries

    • Elastic and allow low-resistance blood flow due to large radius; function as a pressure reservoir during heart relaxation.

    Blood Pressure

    • Force of blood against vessel walls, influenced by blood volume and vessel wall compliance (stretchability).

    Systolic and Diastolic Pressure

    • Systolic: maximum arterial pressure; average is approximately 120 mmHg.
    • Diastolic: minimum pressure; average is approximately 80 mmHg.

    Pulse Pressure

    • Difference between systolic and diastolic pressures.

    Mean Arterial Pressure (MAP)

    • Average pressure pushing blood into tissues throughout the cardiac cycle, calculated as diastolic + 1/3(systolic - diastolic) or CO x total peripheral resistance.

    MAP Determinant

    • Primarily determined by arterioles.

    Muscle Type in Arterioles

    • Composed of smooth muscle.

    Arterioles Function

    • Control the radius of blood vessels through:
      • Vasoconstriction: narrowing blood vessels.
      • Vasodilation: widening blood vessels.

    Radius Alterations in Vessels

    • Influenced by changes in other organs affecting localized blood flow.

    Consistent Blood Flow

    • Steady blood flow is maintained primarily to the brain.

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    Description

    Test your knowledge on cardiac output and stroke volume concepts with these flashcards. Learn the definitions, formulas, and determinants involved in understanding how blood is ejected from the heart. Perfect for students studying physiology or related medical fields.

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