Cardiac Muscle Conduction and Refractory Period Quiz
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Questions and Answers

What happens at 0mV in the cardiac action potential?

  • Ca++ channels and K+ channels both open
  • Ca++ channels open and K+ channels close
  • Ca++ channels and K+ channels both close
  • Ca++ channels close and K+ channels open (correct)

    • What is the purpose of the long refractory period in the cardiac cycle?

  • To accelerate the heart rate
  • To initiate the plateau phase
  • To promote premature contractions
  • To prevent premature contractions (correct)

    • Which part of the heart's conduction system would typically fire the slowest?

  • SA node
  • AV node
  • Purkinje fibers (correct)
  • Atrioventricular bundle

    • What is the purpose of Ca++ binding to troponin in muscle contraction?

    <p>To allow myosin and actin cross bridge formation</p> Signup and view all the answers

    What is the purpose of an ECG or EKG recording?

    <p>To record electrical signals of the heart</p> Signup and view all the answers

    Where is the heart located in the body?

    <p>Between the lungs in the mediastinum</p> Signup and view all the answers

    What is the function of the atria in the heart?

    <p>Collect blood and push it into lower chambers</p> Signup and view all the answers

    Which chamber in the heart is responsible for pumping blood to the body or lungs?

    <p>Left ventricle</p> Signup and view all the answers

    What is the main function of the pulmonary vein?

    <p>Carry oxygenated blood</p> Signup and view all the answers

    What is the role of the epicardium in the heart?

    <p>Produces lubricating fluid</p> Signup and view all the answers

    Which layer of the heart is considered the most superficial?

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

    What is the main function of an artificial pacemaker?

    <p>To deliver electrical impulses for effective heart contractions</p> Signup and view all the answers

    During which phase of the cardiac cycle does systole occur?

    <p>During atrial contraction</p> Signup and view all the answers

    What is the main purpose of an AED (automated external defibrillator)?

    <p>To correct fibrillations</p> Signup and view all the answers

    Which wave represents the repolarization of the ventricles in an electrocardiogram?

    <p>T wave</p> Signup and view all the answers

    What phase of the cardiac cycle involves the closing of semilunar valves and opening of atrioventricular valves?

    <p>Ventricular systole</p> Signup and view all the answers

    What is the purpose of myoglobin in heart cells?

    <p>To store oxygen in muscle cells</p> Signup and view all the answers

    Which heart sound is associated with the closing of atrioventricular valves?

    <p>S1</p> Signup and view all the answers

    What is the normal range for Cardiac Output (CO) in liters per minute?

    <p>4 - 8 L/min</p> Signup and view all the answers

    What is the formula to calculate Cardiac Output (CO)?

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

    What does Ejection Fraction represent in cardiac physiology?

    <p>Percentage of blood pumped by the heart</p> Signup and view all the answers

    Which factor can decrease Heart Rate (HR) according to the text?

    <p>Hypoxia (lack of oxygen)</p> Signup and view all the answers

    Where does nervous control of Heart Rate come from?

    <p>Medulla oblongata</p> Signup and view all the answers

    What is the main effect of sympathetic stimulation on the heart?

    <p>Shortens the repolarization period</p> Signup and view all the answers

    Which response best describes Ejection Fraction?

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

    What is the impact of increased thyroid hormone levels on Heart Rate?

    <p>Increases HR and contractility</p> Signup and view all the answers

    What happens to Stroke Volume if there is less ventricular filling time?

    <p>It decreases</p> Signup and view all the answers

    Which layer lines the chambers of the heart and covers the heart valves?

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

    What are endothelins released by the endothelium known for?

    <p>Regulating growth patterns of cardiac muscle cells</p> Signup and view all the answers

    Which structure in the heart divides it into chambers?

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

    Which valve separates the left atrium from the left ventricle?

    <p>Mitral valve</p> Signup and view all the answers

    Why do semilunar valves make an audible sound when they close?

    <p>They have no muscular attachments</p> Signup and view all the answers

    What is the function of papillary muscles in the heart?

    <p>To close the tricuspid and mitral valves</p> Signup and view all the answers

    What is the main function of coronary circulation?

    <p>To bring blood to the myocardium and other components</p> Signup and view all the answers

    Which cell type initiates and propagates the action potential through the heart?

    <p>Myocardial conducting cells</p> Signup and view all the answers

    What is the main role of the SA node in cardiac conduction?

    <p>Sets normal cardiac rhythm</p> Signup and view all the answers

    What is the significance of gap junctions in cardiac muscle cells?

    <p>Allow ions to travel between cells for proper contractile rhythm</p> Signup and view all the answers

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