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15 Cards in this Set

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