Understanding Resistance and Flow in Vascular Circuits
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Questions and Answers

Which structure in the heart is responsible for initiating the electrical impulses that cause the heart to beat?

  • Purkinje fibers
  • Sinoatrial (SA) node (correct)
  • Atrioventricular (AV) node
  • Bundle of His

    • Which nervous system increases heart rate by releasing norepinephrine?

  • Both sympathetic and parasympathetic nervous systems
  • Parasympathetic nervous system
  • Sympathetic nervous system (correct)
  • Autonomic nervous system

    • Which ion is responsible for initiating action potentials in the heart?

  • Chloride ions
  • Potassium ions
  • Sodium ions
  • Calcium ions (correct)

    • Which factors can increase the right atrial pressure?

    <p>Increased blood volume</p> Signup and view all the answers

    What are Korotkoff's sounds?

    <p>Sounds heard during the measurement of blood pressure using a sphygmomanometer and a stethoscope</p> Signup and view all the answers

    Which factor is defined by Poiseuille's law and directly proportional to the fourth power of the vessel radius?

    <p>None of the above</p> Signup and view all the answers

    Which cell is responsible for performing the contraction of the heart?

    <p>Muscle cells</p> Signup and view all the answers

    Where is the atrioventricular (AV) node located?

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

    What is the function of the bundle of His?

    <p>Conduct electrical impulses from the AV node to the ventricles</p> Signup and view all the answers

    What is the primary pacemaker of the heart?

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

    What is the equation that describes the relationship between pressure gradient, flow rate, and resistance in a cylindrical vessel?

    <p>Hagen-Poiseuille's law</p> Signup and view all the answers

    What is the most frequent cause of atrial fibrillation (AFib)?

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

    What is the equation that relates pressure, flow, and resistance in determining blood flow through the circulation?

    <p>Ohm's law</p> Signup and view all the answers

    What type of flow occurs when blood flows smoothly through a long, straight blood vessel?

    <p>Laminar flow</p> Signup and view all the answers

    Which part of the heart is responsible for generating electrical impulses that cause the heart to beat?

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

    What is the function of the AV node?

    <p>To allow the atria to contract before the ventricles</p> Signup and view all the answers

    What is the role of the Purkinje fibers in the heart?

    <p>To conduct the electrical impulse throughout the ventricles</p> Signup and view all the answers

    Which nervous system releases acetylcholine to slow down the heart rate?

    <p>Parasympathetic nervous system</p> Signup and view all the answers

    According to Ohm's law, what is the relationship between flow rate, pressure difference, and total resistance in a circuit?

    <p>Flow rate is directly proportional to pressure difference and inversely proportional to total resistance.</p> Signup and view all the answers

    What is the relationship between conductance and resistance?

    <p>Conductance is the reciprocal of resistance.</p> Signup and view all the answers

    What effect does an increase in hematocrit have on blood viscosity?

    <p>Increased hematocrit leads to increased blood viscosity.</p> Signup and view all the answers

    What is the advantage of vascular compliance?

    <p>Vascular compliance allows the arterial tree to reduce pressure pulsations.</p> Signup and view all the answers

    During which phase of the cardiac muscle action potential does rapid depolarization occur?

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

    What is the main function of the intercalated discs in the heart?

    <p>All of the above</p> Signup and view all the answers

    Why does the heart function as a functional syncytium, while skeletal muscle does not?

    <p>Because the heart muscle cells work together as a single unit to contract and pump blood</p> Signup and view all the answers

    What is the absolute refractory period in the cardiac muscle action potential?

    <p>The period during which the cardiac muscle cell cannot be stimulated to depolarize again, no matter how strong the stimulus is</p> Signup and view all the answers

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