2.3
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Questions and Answers

What is a major determinant of Pulmonary Vascular Resistance (PVR)?

  • Heart rate
  • Blood flow rate
  • Transmural pressure difference (correct)
  • Systemic blood pressure

    • What allows for less resistance to flow in the pulmonary circulation compared to systemic circulation?

  • Heart rate
  • Vessel diameter
  • Transmural pressure difference (correct)
  • Blood viscosity

    • What type of pressure drop is observed in the pulmonary circulation from the pulmonary artery to the left atrium?

  • ~ 100 mmHg
  • ~ 150 mmHg
  • ~ 50 mmHg
  • ~ 10 mmHg (correct)

    • What plays a major role in determining Pulmonary Vascular Resistance (PVR) besides active smooth muscle contraction?

    <p>Passive factors</p> Signup and view all the answers

    How does Pulmonary Vascular Resistance (PVR) compare to Systemic Vascular Resistance (SVR)?

    <p>PVR is 1/10 of SVR</p> Signup and view all the answers

    In which zone of the lung does capillary pressure never exceed alveolar pressure?

    <p>Zone 1</p> Signup and view all the answers

    What characterizes Zone 2 of the lung in terms of blood flow?

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

    How is pulmonary capillary wedge pressure (PCWP) estimated?

    <p>Similar to left atrial pressure</p> Signup and view all the answers

    What does a Swan-Ganz catheter balloon tip floated into the pulmonary artery estimate?

    <p>Pulmonary capillary wedge pressure (PCWP)</p> Signup and view all the answers

    During exercise, which lung zone experiences continuous blood flow?

    <p>Zone 3</p> Signup and view all the answers

    What is the primary function of pulmonary circulation?

    <p>Gas exchange</p> Signup and view all the answers

    How many pulmonary capillaries supply the alveoli in the lungs?

    <p>280 billion</p> Signup and view all the answers

    Where do lung structures distal to terminal bronchioles receive oxygen from?

    <p>Alveolar air</p> Signup and view all the answers

    What is the average diameter of pulmonary capillaries?

    <p>~6 um</p> Signup and view all the answers

    In the absence of pulmonary circulation, what can serve as collateral circulation for gas exchange in the airways?

    <p>Bronchial veins</p> Signup and view all the answers

    What is the purpose of Hypoxic Pulmonary Vasoconstriction (HPV)?

    <p>To divert blood away from poorly ventilated alveoli</p> Signup and view all the answers

    What happens when the PO2 of alveoli decreases in the context of Hypoxic Pulmonary Vasoconstriction?

    <p>Smooth muscle in arterioles contracts causing vasoconstriction</p> Signup and view all the answers

    What does Hypoxic Pulmonary Vasoconstriction aim to mitigate?

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

    How does Hypoxic Pulmonary Vasoconstriction affect the resistance to blood flow in hypoventilated alveoli?

    <p>Increases resistance to blood flow</p> Signup and view all the answers

    What is the volume and distributive aspect of pulmonary circulation when lying down?

    <p>Increased blood flow per unit volume in gravity-dependent lung regions</p> Signup and view all the answers

    What is the term for the phenomenon where blood flow is directed away from poorly ventilated areas of the lung to well-ventilated regions?

    <p>Hypoxic pulmonary vasoconstriction</p> Signup and view all the answers

    In pulmonary circulation, what is the main determinant of arterial pressure?

    <p>The cardiac output from the left ventricle</p> Signup and view all the answers

    How does increased cardiac output affect pulmonary vessels?

    <p>Decreases pulmonary vascular resistance</p> Signup and view all the answers

    What is the term for the condition where fluid accumulates in the lungs impairing gas exchange?

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

    How does the position of vessels in the lung affect their resistance?

    <p>Vessels closer to the pleura have lower resistance</p> Signup and view all the answers

    What happens to the alveolar capillary walls when blood volume inside increases?

    <p>They distend</p> Signup and view all the answers

    At high lung volumes, which of the following statements is true regarding pulmonary vascular resistance?

    <p>Alveolar vessel resistance increases</p> Signup and view all the answers

    What happens to pulmonary vascular resistance with increased cardiac output?

    <p>Pulmonary vascular resistance decreases</p> Signup and view all the answers

    How does recruitment affect pulmonary vascular resistance?

    <p>Opens closed capillaries</p> Signup and view all the answers

    During exercise, what contributes to the decrease in pulmonary vascular resistance?

    <p>Distention of blood vessels</p> Signup and view all the answers

    How does positive pressure ventilation (PPV) affect pulmonary blood flow?

    <p>Decreases pulmonary blood flow by reducing right ventricular preload</p> Signup and view all the answers

    What is the main effect of PPV on the afterload of the right ventricle?

    <p>Increases afterload by elevating PVR</p> Signup and view all the answers

    Which condition is likely to be associated with an increase in Zone 1 in the lungs?

    <p>Positive alveolar pressures and decreased venous return</p> Signup and view all the answers

    What effect does positive pressure ventilation, especially with PEEP, have on low ventilation-perfusion ratios (shunt)?

    <p>Decreases low ventilation-perfusion ratios</p> Signup and view all the answers

    How does a decrease in blood volume to the left heart impact left ventricular filling and stroke volume?

    <p>Decreases left ventricular filling and stroke volume</p> Signup and view all the answers

    What happens to intrathoracic pressure during positive pressure ventilation?

    <p>Elevates intrathoracic pressure</p> Signup and view all the answers

    How does resistance to pulmonary blood vessels change during inspiration?

    <p>Increases during inspiration</p> Signup and view all the answers

    What is the effect of negative-pressure (eupnea) breathing on LV filling and stroke volume?

    <p>Decreases LV filling and stroke volume</p> Signup and view all the answers

    How does decreased CO affect total thoracic blood volume?

    <p>Decreases total thoracic blood volume</p> Signup and view all the answers

    What is the impact of decreased RV filling & SV on RVCO?

    <p>Decreases RVCO</p> Signup and view all the answers

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