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15 Cards in this Set
- Front
- Back
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Which structures in the lungs are involved in gas transport?
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Conducting airways(trachea, bronchi, bronchioles and terminal bronchioles).
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Define ventilation.
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Transport of gas from the environment to the alveoli fo gas exchange.
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Define perfusion(Q).
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Pulmonary blood flow to the alveoli.
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What is the most common cause of hypoxemia?
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V/Q mismatch
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What are some major causes of V/Q mismatch?
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1. Fibrosing mediastinitis
2. Effusion 3. Vasculitis 4. One pulmonary artery(hyperplasia) 5. Neoplasm 6. Embolism |
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How do ventilation and perfusion in the upright position change from the bases to the apices of the lungs.
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Decline
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What is the normal distribution of ventilation and perfusion in a standing person.
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Ventilation, highest at base, lowest at apex
Perfusion, highest at base, lowest at apex. |
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Why is the V/Q ratio low at the base and high at the apex?
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The relative change in blood flow from the apex to the base is greater than the relative change in ventilation.
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What happens to PO2 and PCO2 if the ventilation to an alveolus is reduced relative to its perfusion.
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PO2: falls because less O2 is delivered
PCO2, rises because less CO2 is expired |
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What is a shunt?
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Perfusion with no/low ventilation.
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What is the Alveolar-arterial(A-a) gradient?
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The discrepancy between alveolar and arteriolar O2 partial pressures.
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At what V/Q ratio does the most effecient gas exchange occur?
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1
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What is the V/Q ratio for the whole lung at rest?
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Ventilation=4.2L/min
Perfusion=5.5L/min V/Q= 4.2/5.5=0.8 |
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What causes low V/Q ratio?
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Inadequate ventilation or excessive blood flow.
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What is the result of low V/Q ratio?
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Decreased alveolar O2 tension and increased CO2 tension.
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