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24 Cards in this Set
- Front
- Back
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ventilation |
refers to airflow |
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perfusion |
refers to blood flow |
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apex of the lung |
alveoli at increase stress, decreased potential to expand and contract, greater intrapleural pressure |
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V/Q at apex |
high! |
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where does emphysema occur first? |
apex of the lung |
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base of the lung |
low intrapleural pressure, smaller alveoli, greater potential to expand, highest blood flow |
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V/Q of base |
low! |
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[gases] of lung |
apex is more like atmosphere (high O2, very low CO2 = hyperventilation) base approaches venous blood (low O2, high CO2 = hypoventilation) |
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normal PCO2 |
40 mmHg |
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uniform V/Q ratio |
recumbent position, exercise, microgravity |
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decreased V/Q ratio |
obstruct ventilation = asthma, bronchitis, tumors, edema, hypoventilation (substance abuse) |
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increased V/Q ratio |
obstruct perfusion = tumors, emboli, thrombi, cardiac failure |
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airway SM + hypoxia |
contraction |
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airway SM + hypocapnia |
contraction |
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airway SM + hypercapnia |
relaxation |
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vascular SM + hypoxia |
vasoconstriction |
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vascular SM + hypercapnia |
vasodilation |
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pulmonary shunt |
blood enters pulm. veins w/o going through a functional alveolar unit = no gas exchange (V/Q = 0) |
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pathological shunt |
no ventilation in alveoli due to edema, pneumonia, mucus plugs, AW s.m. contraction; abn. connections b/t a & v (fistulas) |
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shunt calculation |
Qs/Qt = (CiO2 - CaO2)/(CiO2 - CvO2) |
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CiO2 |
dissolved + HbO2 = (.003 X PaO2) + (1.34 X Hb X SiO2) |
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what is most affected by gravity? |
perfusion |
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where does 1/1 V/Q ratio occur while standing? |
mid sections of the lung |
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normal anatomic shunt |
~3% |
