Cardiac Action Potential and Conduction System Quiz
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Questions and Answers

What happens at 0mV in the cardiac cycle?

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

    • What is the role of Ca++ in muscle contraction?

  • Ca++ inhibits muscle contraction
  • Ca++ binds to troponin to allow myosin and actin cross bridge (correct)
  • Ca++ blocks cross-bridge formation
  • Ca++ is not involved in muscle contraction

    • Which part of the heart has the lowest firing rate?

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

    • What is the purpose of an ECG or EKG?

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

    If the SA node was not under endocrine control, how many times would it fire per minute?

    <p>100 - 120 times</p> Signup and view all the answers

    Where is the heart located?

    <p>In a space called mediastinum</p> Signup and view all the answers

    Which chamber of the heart collects blood and pushes it into the lower chambers?

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

    What is the purpose of auricles in the heart?

    <p>To hold blood and empty into atria</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

    Where does CO2 leave and O2 enter in the pulmonary capillaries?

    <p>In the pulmonary arteries</p> Signup and view all the answers

    Which vessel is the only vein to carry oxygenated blood?

    <p>Pulmonary vein</p> Signup and view all the answers

    What does the P wave represent in the cardiac cycle?

    <p>Depolarization of the atria</p> Signup and view all the answers

    Which phase of the cardiac cycle involves the closure of semilunar valves and ventricular relaxation?

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

    What is the main function of an artificial pacemaker in the heart?

    <p>To ensure effective heart contractions</p> Signup and view all the answers

    Which phase marks the pumping of blood into circulation during the cardiac cycle?

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

    What is the primary purpose of AEDs in relation to the heart?

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

    What represents the amount of blood left in the ventricles after stroke volume is pushed out?

    <p>End systolic volume (ESV)</p> Signup and view all the answers

    Which of the following is responsible for the first heart sound, S1?

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

    What does S4 indicate in terms of heart function?

    <p>Blood being pushed into a stiff ventricle</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 stroke volume (SV) based on end-diastolic volume (EDV) and end-systolic volume (ESV)?

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

    Which factor can decrease heart rate according to the text?

    <p>Hypoxia (lack of O2)</p> Signup and view all the answers

    Where does nervous control of heart rate primarily originate from?

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

    What is the term used to describe increased ventricular stretch leading to more powerful contractions?

    <p>$Starling mechanism$</p> Signup and view all the answers

    During exercise, what happens to stroke volume as heart rate increases?

    <p>$SV$ decreases as $HR$ increases</p> Signup and view all the answers

    What is the percentage range for normal ejection fraction?

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

    'S7' is a term used when referring to which condition according to the text?

    <p>$S3$ and $S4$ occurring together</p> Signup and view all the answers

    What cell type in the heart is responsible for initiating and propagating the action potential through the heart?

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

    Which structure ensures that cardiac muscle cells do not rip apart during contractions?

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

    What is the primary function of the Sinoatrial (SA) node in the heart?

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

    Which structure receives impulses from the AV node and branches into right and left bundle branches?

    <p>Bundle of His</p> Signup and view all the answers

    What is the function of semilunar valves in the heart?

    <p>Ensure unidirectional blood flow</p> Signup and view all the answers

    During which phase of depolarization do cardiac contractile cells experience a plateau?

    <p>At peak depolarization</p> Signup and view all the answers

    What causes a heart murmur during auscultation?

    <p>Altered blood flow due to valve disorders</p> Signup and view all the answers

    Which heart chamber receives deoxygenated blood from systemic circulation?

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

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