Cardiac Action Potential Features
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Questions and Answers

What occurs at 0mV during repolarization?

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

    • What prevents premature contractions in the heart?

  • Fast Ca++ channels
  • Long refractory period (correct)
  • Calcium ion influx
  • K+ channel inhibition

    • Which node would fire 80 - 100 times per minute without endocrine control?

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

    • What component of an ECG records electrical signals of the heart?

    <p>Electrodes on the body</p> Signup and view all the answers

    Which part of the heart has the lowest firing rate recorded at 28 BPM?

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

    What is the approximate volume of fluid pumped by the heart per minute?

    <p>5.25 L</p> Signup and view all the answers

    In the heart, where does the base location relative to the apex?

    <p>Superior and medial</p> Signup and view all the answers

    Which blood vessels attach at the base of the heart?

    <p>Aorta and pulmonary trunk</p> Signup and view all the answers

    What is the function of ventricles in the heart?

    <p>Pump blood to the lungs or body</p> Signup and view all the answers

    Which layer of the heart produces lubricating fluid in the pericardial cavity?

    <p>Visceral layer</p> Signup and view all the answers

    What is the middle thickest layer in the heart that consists of muscle cells, nerve fibers, and blood vessels?

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

    What does the T wave represent in the cardiac cycle?

    <p>Repolarization of ventricles</p> Signup and view all the answers

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

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

    What is the main function of an artificial pacemaker?

    <p>Ensuring effective heart contractions with electrical impulses</p> Signup and view all the answers

    What is the role of myoglobin in heart muscle cells?

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

    Which valve closes during ventricular diastole?

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

    What is the normal amount of blood pushed out by the ventricles during each heartbeat?

    <p>$70-80$ mL</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 does S2, the second heart sound, represent?

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

    Which condition is referred to as S7?

    <p>Presence of S3 and S4 together</p> Signup and view all the answers

    What is the formula for Cardiac Output (CO)?

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

    What is the normal range for Ejection Fraction?

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

    What is the difference between Cardiac Reserve and Max HR?

    <p>Cardiac Reserve is the difference between Max CO and Resting CO</p> Signup and view all the answers

    'Target heart rate' refers to a range that aims to keep what high?

    <p>Cardiac Output</p> Signup and view all the answers

    'What can decrease heart rate among the following factors?'

    <p>Acidosis (excess hydrogen ions)</p> Signup and view all the answers

    Which layer of the heart covers the heart valves and is continuous with the lining of blood vessels?

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

    What cells release endothelins and regulate growth patterns of cardiac muscle cells?

    <p>Endothelial cells</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

    In which chamber of the heart are pectinate muscles present?

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

    Which part of the heart receives oxygenated blood from the pulmonary veins?

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

    What structure in the heart closes due to papillary muscles?

    <p>Atrioventricular valves</p> Signup and view all the answers

    What cells in the heart have a long refractory period to prevent tetany?

    <p>Cardiac muscle cells</p> Signup and view all the answers

    Where is the Sinoatrial (SA) node located in the heart?

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

    What structure receives an impulse from the AV node and branches into right and left bundle branches?

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

    What happens at +30mV in cardiac contractile cells during membrane potentials?

    <p>Na+ channels close and Ca++ channels open.</p> Signup and view all the answers

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