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Questions and Answers

Which equation is used to determine the physiologic dead space?

  • Bohr equation (correct)
  • Charles's Law
  • Boyle's Law
  • Dalton's Law

    • What does an increased arterial-alveolar CO2 difference suggest?

  • Normal lung function
  • Decreased physiological dead space
  • Increased ventilation-perfusion mismatch (correct)
  • Overperfusion of alveoli

    • Intrapulmonary shunting refers to:

  • Efficient oxygen exchange in the lungs
  • Enhanced ventilation without perfusion
  • Exchange of gases at the alveolar level
  • Blood perfusion without ventilation in alveoli (correct)

    • Which of the following contributes to anatomic shunts?

    <p>Systemic venous blood entering the left ventricle directly</p> Signup and view all the answers

    What does the shunt equation divide all alveolar-capillary units into?

    <p>Well-matched and poorly-matched V/Q units</p> Signup and view all the answers

    How does a shunt-like state differ from anatomic shunts?

    <p>A shunt-like state involves impaired ventilation with excess perfusion</p> Signup and view all the answers

    What contributes to normal physiologic shunts?

    <p>Venous blood that bypasses pulmonary capillaries</p> Signup and view all the answers

    What does an absolute intrapulmonary shunt refer to?

    <p>'True shunts' where venous blood perfuses unventilated alveoli</p> Signup and view all the answers

    What is the primary purpose of the shunt equation in the context of ventilation-perfusion ratios?

    <p>To quantify the extent of venous admixture</p> Signup and view all the answers

    Which of the following statements best describes the concept of physiologic dead space?

    <p>It represents alveoli that are well-ventilated but not perfused</p> Signup and view all the answers

    How is the Bohr equation relevant to the understanding of ventilation-perfusion ratios?

    <p>It describes the relationship between CO2 elimination and alveolar ventilation</p> Signup and view all the answers

    Why is venous admixture a concern when analyzing ventilation-perfusion ratios?

    <p>It results in a decrease in arterial oxygen content</p> Signup and view all the answers

    Which scenario best describes a ventilation-perfusion mismatch?

    <p>Alveoli with high ventilation and low perfusion</p> Signup and view all the answers

    When considering regional differences in ventilation-perfusion ratios, what effect does gravity have on V/Q matching?

    <p>Gravity causes higher V/Q ratios at the lung bases</p> Signup and view all the answers

    Which statement accurately reflects the consequence of a significant shunt in the lungs?

    <p>'Left-to-right' intrapulmonary shunting of blood</p> Signup and view all the answers

    In the context of venous admixture, what accurately describes 'Bohr effect'?

    <p>'Bohr effect' causes a right shift in the oxyhemoglobin dissociation curve</p> Signup and view all the answers

    Which factor plays a key role in maintaining gas exchange by bringing O2 into the lungs and removing CO2?

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

    What is a common influence on mixed venous blood that brings CO2 into the lungs and takes up alveolar O2?

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

    Which neural regulation factor may lead to an increase in pulmonary vascular resistance and a decrease in distensibility?

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

    What effect do pulmonary vasoconstrictors have on pulmonary vascular resistance (PVR)?

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

    Intrinsic autoregulation leading to vasoconstriction is mainly attributed to which phenomenon?

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

    Which of the following substances contributes to decreased PVR and increased blood volume?

    <p>$\text{PGE1}$ and $\text{PGI2}$</p> Signup and view all the answers

    'Bohr equation' is related to which concept in gas exchange physiology?

    <p>Venous admixture</p> Signup and view all the answers

    'Physiologic dead space' is primarily associated with which aspect of gas exchange?

    <p>$\text{Ventilation-perfusion mismatch}$</p> Signup and view all the answers

    What condition results in a V/Q ratio approaching infinity?

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

    In which scenario would you observe alveolar dead space?

    <p>Intrapulmonary shunts causing underventilation</p> Signup and view all the answers

    Which condition allows fresh gas to reach alveoli lacking perfusion?

    <p>Physiologic dead space</p> Signup and view all the answers

    What happens when the ventilation-perfusion ratio (VA/Q) is higher than normal?

    <p>PAO2 increases and PACO2 decreases</p> Signup and view all the answers

    What is the consequence of a ventilation-perfusion ratio (VA/Q) less than normal?

    <p>PAO2 decreases and PACO2 increases</p> Signup and view all the answers

    What is a major cause of hypoxemia related to ventilation-perfusion mismatch?

    <p>Intrapulmonary shunts causing underventilation</p> Signup and view all the answers

    In the context of ventilation-perfusion ratios, what do alveolar dead space and intrapulmonary shunt represent?

    <p>Low VA/Q</p> Signup and view all the answers

    How do small shunts manifest when measuring PaO2 during FiO2 1.0 (100%)?

    <p>Unchanged PaO2 values</p> Signup and view all the answers

    What are the consequences of ventilation-perfusion ratios close to 1.0?

    <p>Alveolar PO2s around 100 mmHg and PCO2s close to 40 mmHg</p> Signup and view all the answers

    Which scenario increases the required minute ventilation for gas exchange according to the text?

    <p>Extrapulmonary shunts like CHD/VSD</p> Signup and view all the answers

    What occurs when the VA/Q ratio is higher than normal in terms of oxygen and carbon dioxide levels?

    <p>Increase in O2 delivery relative to its removal</p> Signup and view all the answers

    When does the Bohr equation not respond to an increase in FiO2?

    <p>In case of increased A-a O2 difference</p> Signup and view all the answers

    Why does intrapulmonary shunt cause hypoxemia?

    <p>Alveoli are underventilated</p> Signup and view all the answers

    How does a ventilation-perfusion ratio less than normal affect alveolar gases?

    <p>Alveolar gases resembling mixed venous blood</p> Signup and view all the answers

    In terms of ventilation-perfusion ratios, what happens when the PO2 increases and PCO2 decreases?

    <p>A higher than normal VA/Q ratio</p> Signup and view all the answers

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