Cardiac Cycle Overview Quiz
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Questions and Answers

Which of the following variables does NOT influence stroke volume?

  • Heart rate (correct)
  • Inotropic agents
  • Venous return
  • Afterload
  • What is the typical end-diastolic volume (EDV) in a resting adult?

  • 130 mL (correct)
  • 60 mL
  • 150 mL
  • 100 mL
  • What is the typical end-systolic volume (ESV) in a resting adult?

  • 50 mL
  • 70 mL
  • 60 mL (correct)
  • 40 mL
  • What is the formula for calculating stroke volume (SV)?

    <p>SV = EDV - ESV</p> Signup and view all the answers

    Which of the following factors influences end-diastolic volume (EDV)?

    <p>Venous return</p> Signup and view all the answers

    Which of the following factors influences end-systolic volume (ESV)?

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

    What is the primary mechanism by which sympathetic stimulation increases heart rate?

    <p>Increasing the firing rate of the SA node by opening Ca2+ channels</p> Signup and view all the answers

    What is the role of thyroid hormone (TH) in increasing heart rate?

    <p>TH increases the number of β1-adrenergic receptors on SA nodal cells, making them more responsive to NE and EPI</p> Signup and view all the answers

    How do certain chemical compounds, such as nicotine, cocaine, and caffeine, increase heart rate?

    <p>They increase the release of NE and EPI from the adrenal medulla</p> Signup and view all the answers

    What is the role of Ca2+ influx in the SA nodal cells during sympathetic stimulation?

    <p>Ca2+ influx is responsible for the depolarization of the SA nodal cells, increasing their firing rate</p> Signup and view all the answers

    How do drugs that act on this pathway increase heart rate?

    <p>They directly open Ca2+ channels in SA nodal cells</p> Signup and view all the answers

    What is the role of the AV node in the increase in heart rate during sympathetic stimulation?

    <p>The AV node is inhibited by sympathetic stimulation, decreasing the conduction delay</p> Signup and view all the answers

    Which of the following best describes the term 'systole'?

    <p>Contraction of a heart chamber</p> Signup and view all the answers

    What initiates the contraction of the ventricular muscles?

    <p>The Purkinje fibers of the conduction system</p> Signup and view all the answers

    What is the primary driving force that ensures the unidirectional movement of blood through the heart and the opening and closing of heart valves?

    <p>Ventricular contraction and relaxation</p> Signup and view all the answers

    During the initial phase of ventricular contraction, what happens to the atrioventricular (AV) valves?

    <p>They are forced closed to prevent backflow into the atria</p> Signup and view all the answers

    Which of the following statements accurately describes the relationship between pressure changes and the movement of blood in the heart?

    <p>Blood moves along a pressure gradient, from an area of greater pressure to an area of lesser pressure</p> Signup and view all the answers

    What is the purpose of the tendinous cords and papillary muscles in relation to the AV valves?

    <p>To brace and prevent the AV valves from bulging into the atria</p> Signup and view all the answers

    During the initial phase of ventricular contraction, what is the state of the semilunar valves?

    <p>They are closed to prevent backflow from the arterial trunks</p> Signup and view all the answers

    Which of the following statements accurately describes the action of heart valves during ventricular contraction?

    <p>The atrioventricular valves close, and the semilunar valves open</p> Signup and view all the answers

    During the initial phase of ventricular contraction, what happens to the blood volume within the ventricular chambers?

    <p>It remains the same as no blood enters or leaves the ventricles</p> Signup and view all the answers

    Which of the following statements accurately describes the relationship between the opening and closing of heart valves?

    <p>As the atrioventricular valves close, the semilunar valves open</p> Signup and view all the answers

    What event marks the beginning of the ventricular ejection phase?

    <p>The semilunar valves open due to increased ventricular pressure</p> Signup and view all the answers

    Which of the following analogies best describes the action of heart valves during the cardiac cycle?

    <p>It's like a pair of swinging doors, where one door closes as another opens</p> Signup and view all the answers

    Which of the following statements about venous return is accurate?

    <p>During exercise, venous return can approximately double compared to its rate at rest.</p> Signup and view all the answers

    What is the primary factor that determines balanced ventricular output?

    <p>The inherent ability of the heart to contract more forcefully in response to increased venous return.</p> Signup and view all the answers

    What happens when you start to exercise and venous return from the body into the right side of the heart increases?

    <p>Both the right and left ventricles contract more forcefully, increasing stroke volume and cardiac output.</p> Signup and view all the answers

    What is the relationship between stroke volume and inotropic agents?

    <p>Stroke volume is altered by external factors, including inotropic agents.</p> Signup and view all the answers

    What is the effect of a low resting heart rate on venous return?

    <p>A low resting heart rate increases venous return.</p> Signup and view all the answers

    What is the consequence of low blood volume or an abnormally high heart rate?

    <p>It decreases venous return, end-diastolic volume, preload, and ultimately stroke volume.</p> Signup and view all the answers

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