Cardiac Conduction System and Excitation-Contraction Coupling
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Questions and Answers

What is the function of the atria in the heart?

  • Connect to the aorta
  • Pump blood to the body
  • Collect blood and push it into lower chambers (correct)
  • Carry oxygenated blood

    • Where is the base of the heart located?

  • Posterior to the pericardium
  • Inferior and lateral to the apex
  • Anterior to the mediastinum
  • Superior and medial to the apex (correct)

    • Which vessel attaches at the base of the heart?

  • Pulmonary vein
  • Aorta (correct)
  • Inferior vena cava
  • Pulmonary artery

    • Where is the epicardium located in relation to the myocardium?

    <p>Most superficial layer</p> Signup and view all the answers

    Which vessels are responsible for carrying deoxygenated blood to the lungs?

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

    What is the main purpose of the pericardial cavity?

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

    What is the function of Ca++ channels at 0mV in repolarization?

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

    If the endocrine control was absent, how many times per minute would the AV node fire?

    <p>40 - 60</p> Signup and view all the answers

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

    <p>Allow the myosin and actin cross bridge</p> Signup and view all the answers

    What would be the heart rate range if the Purkinje fibers were firing at 15 - 20 times per minute?

    <p>15 - 20 BPM</p> Signup and view all the answers

    What would happen if the Ca++ channels remained open during repolarization?

    <p>Premature contractions would occur</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 phase</p> Signup and view all the answers

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

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

    Which of the following is characteristic of the T wave in the cardiac cycle?

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

    In which phase of the cardiac cycle is the blood pushed out by the ventricles known as end diastolic volume (EDV) or preload?

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

    Which of the following statements correctly describes the role of myoglobin in heart cells?

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

    During which phase of the cardiac cycle do semilunar valves close and atrioventricular valves are also closed?

    <p>Ventricular diastole phase</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

    Which heart sound is associated with blood being pushed into a stiff or hypertrophic ventricle?

    <p>S4</p> Signup and view all the answers

    What does an increased level of thyroid hormone do to heart rate and contractility?

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

    Which neurotransmitter is released during parasympathetic stimulation of the heart?

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

    What does caffeine and nicotine do to heart rate?

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

    Which reflex involves pressure and stretch leading to increased parasympathetic stimulation of the heart?

    <p>Baroreceptor reflex</p> Signup and view all the answers

    What can cause a decrease in heart rate?

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

    'S7' is referred to when both which sounds are present at the same time?

    <p>'S3' and 'S4'</p> Signup and view all the answers

    'Cardiac reserve' is defined as the difference between which two values?

    <p>'Max CO' and 'resting CO'</p> Signup and view all the answers

    What is the function of the endothelium in the heart?

    <p>Act as a barrier between the blood and heart muscle</p> Signup and view all the answers

    Which type of valve separates the atria from the ventricles in the heart?

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

    Where does the right ventricle receive deoxygenated blood from?

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

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

    <p>Muscles for cardiac conduction</p> Signup and view all the answers

    What is the primary function of coronary circulation in the heart?

    <p>Provide oxygenated blood to cardiac muscle</p> Signup and view all the answers

    What feature allows ions to travel between adjacent cardiac muscle cells?

    <p>Gap junctions</p> Signup and view all the answers

    Which structure in the heart slows down impulses and forces contraction of the atrioventricular septum?

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

    What happens to Na+ channels in cardiac conductive cells during spontaneous depolarization?

    <p>They open slowly to create depolarization</p> Signup and view all the answers

    What is the main characteristic of cardiac contractile cells during repolarization?

    <p>A plateau phase at +30mV</p> Signup and view all the answers

    What initiates an electrical potential at a fixed rate in cardiac muscle cells?

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

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