Cardiovascular System: Physiology and Pathophysiology
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Questions and Answers

What is the main cause of the contraction of cardiac muscle (systole)?

  • Opening of voltage gated Na+ channels
  • Closing of sodium ion channels and the opening of potassium ion channels
  • Excessive influx of anions (Cl– ions)
  • Closing of voltage gated Ca+2 channels (correct)

    • What is the process that results in the return of ions to their previous resting state in cardiac muscle?

  • Conductivity
  • Refractory Period
  • Repolarization (correct)
  • Hyperpolarization

    • What causes hyperpolarization in cardiac muscle?

  • Closing of potassium ion channels
  • Influx of anions (Cl– ions) through chloride channels (correct)
  • Excessive efflux of potassium due to open channels
  • Opening of voltage gated Na+ channels

    • What does the refractory period refer to in excitable membranes?

    <p>The amount of time it takes for a membrane to be ready to respond to a second stimulus</p> Signup and view all the answers

    From where does the cardiac electric impulse originate in the heart?

    <p>SA node (Pacemaker)</p> Signup and view all the answers

    What role does the AV node play in the heart's conductive system?

    <p>Allows passage of the electric impulse slowly (AV nodal delay)</p> Signup and view all the answers

    What is responsible for transmitting the cardiac electric impulse from the AV node to the right and left ventricles?

    <p>Right and left bundle branches</p> Signup and view all the answers

    What is the final step in the heart's conductive system?

    <p>Purkinje fibers distributing impulse to all cells</p> Signup and view all the answers

    What is the primary characteristic of the cardiac muscle?

    <p>Auto-rhythmicity</p> Signup and view all the answers

    Which cells in the heart can generate action potential spontaneously?

    <p>SA node and AV node</p> Signup and view all the answers

    What is the normal pacemaker of the heart?

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

    What factor can cause an increase in heart rate (↑HR)?

    <p>Sympathetic stimulation</p> Signup and view all the answers

    During which phase of action potential does depolarization occur?

    <p>Phase 0</p> Signup and view all the answers

    What causes a large influx of sodium ions inside the cardiac cell during depolarization?

    <p>Opening of voltage-gated sodium channels</p> Signup and view all the answers

    Which type of stimulation can lead to a decrease in heart rate (↓HR)?

    <p>Parasympathetic stimulation</p> Signup and view all the answers

    What is the primary function of the SA node in the heart?

    <p>Generating action potential spontaneously</p> Signup and view all the answers

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