Cardiac Conduction System and Action Potentials
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Questions and Answers

What is the role of Ca++ channels at 0mV during repolarization?

  • Binding to troponin for muscle contraction
  • Allowing the myosin and actin cross bridge
  • Opening to initiate repolarization
  • Closing to prevent premature contractions (correct)
  • Which heart node would fire 80 - 100 times per minute without endocrine control?

  • Bundle branches
  • SA node (correct)
  • AV node
  • Atrioventricular bundle
  • What is the function of slow Ca++ channels in the heart?

  • Closing to prevent arrhythmias
  • Initiating repolarization
  • Allowing for the plateau phase (correct)
  • Inducing myosin-actin cross-bridge formation
  • Which part of the heart has the lowest firing rate among the listed nodes and fibers?

    <p>Purkinje fibers</p> Signup and view all the answers

    What is the primary purpose of an Electrocardiogram (ECG or EKG)?

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

    Which layer of the heart is the most superficial?

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

    What is the purpose of the auricles in the heart?

    <p>To hold blood and empty into atria</p> Signup and view all the answers

    Which chamber of the heart connects to the pulmonary trunk?

    <p>Right ventricle</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

    How many chambers does a typical heart have?

    <p>4</p> Signup and view all the answers

    What separates the heart from other structures within the chest?

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

    During which phase of the cardiac cycle does the P wave represent the depolarization of the atria?

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

    What is the function of an artificial pacemaker in relation to heart contractions?

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

    Which phase of the cardiac cycle is characterized by ventricular relaxation and semilunar valves closing?

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

    What is the main purpose of an AED (Automated External Defibrillator)?

    <p>Correct fibrillations</p> Signup and view all the answers

    Which phase of the cardiac cycle involves the pumping of blood into circulation?

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

    What is the average amount of blood pushed out by the ventricles in each heartbeat called?

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

    Which event in the cardiac cycle is associated with the first heart sound, S1?

    <p>Closing of the atrioventricular valves</p> Signup and view all the answers

    What condition might be present if both the S3 and S4 heart sounds are heard together?

    <p>S7</p> Signup and view all the answers

    What calculation is used to determine the cardiac output (CO)?

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

    What is the normal range for ejection fraction (EF) in cardiac physiology?

    <p>50% - 70%</p> Signup and view all the answers

    During exercise, how does an increase in heart rate (HR) affect cardiac output (CO)?

    <p>Increases CO</p> Signup and view all the answers

    What is the target heart rate used to maintain high cardiac output during physical activity based on?

    <p>% of maximum heart rate</p> Signup and view all the answers

    Which layer of the heart releases endothelins that act as strong vasoconstrictors?

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

    What is the role of the Fossa ovalis in the heart?

    <p>Was a foramen ovale while a fetus</p> Signup and view all the answers

    Which chamber of the heart receives deoxygenated blood from systemic circulation?

    <p>Right atrium</p> Signup and view all the answers

    What is the function of the moderator band in the heart?

    <p>Assists in closing the tricuspid valve</p> Signup and view all the answers

    Why do semilunar valves produce an audible sound as they close?

    <p>Due to having no muscular attachments</p> Signup and view all the answers

    What is the purpose of anastomosis in coronary circulation?

    <p>To connect blood vessels and allow alternative flow paths</p> Signup and view all the answers

    Which type of cardiac muscle cells are responsible for initiating and propagating action potentials?

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

    Where is the SA node located in the heart?

    <p>Right atrium</p> Signup and view all the answers

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