Other Factors Contributing to Non- Uniform Distribution of Perfusion Right pulmonary artery comes off at an acute angle. Therefore, there is more flow to the left lung.
Factors Contributing to Non-Uniform Distribution of Ventilation Diaphragm and ribcage association with lungs provides for greater expansion at the base than at apex outer parencyma expands more than inner Weight of the lung and blood at the base greater starting volume at apex (less ventilation upon inhalation) results in less negative pleural pressure at base, favoring greater expansion at apex Net result: more ventilation at the base than at the apex.
Powder Dye (x mg) Concentration (x mg / total ml) V/Q Matching
Powder Dye (V) Fluid Flow (Q) Concentration (V/Q) V/Q Matching
Powder Dye (V) Fluid Flow (Q) Concentration (V/Q)
Powder Dye (V) Fluid Flow (Q) Concentration (V/Q)
Powder Dye (V) Fluid Flow (Q) Concentration (V/Q) V/Q Matching
Powder Dye (V) Fluid Flow (Q) Concentration (V/Q)
Powder Dye (V) Fluid Flow (Q) Concentration (V/Q)
2345 TOP BOTTOM Rib Number L/min or % lung volume Ventilation Blood Flow V A /Q C V A / Q C
PCO 2 (mmHg) PO 2 (mmHg) Low V A /Q High V A /Q V/Q Matching mixed venous blood Tracheal air
VAVA (L/min) Q V A /Q PO 2 PCO 2 mmHg pH V/Q Matching
Why is arterial P O 2 lower than average (ideal) alveolar P O 2 ? When pulmonary veins joins combining volumes of blood that have different oxygen concentrations, the final concentration of oxygen is a simple, linear function of Oxygen content of each volume Sum of the volumes (final volume)
pv V/Q=10/10 O 2 Concentration inVol% V/Q=1/10V/Q=10/ X 10 = X 10 = X 1 = / 21 = V/Q Matching mv (pa) X 10 = X 10 = X 1 = / 21 = 83.3 (60)(150) (100) (PO2) (70)
Hb Saturation (%) P O (mmHg) O 2 Content (ml O 2 /dl blood) Total O 2 Oxygen Transport
Why is arterial P O 2 lower than average (ideal) alveolar P O 2 ? When pulmonary veins joins combining volumes of blood that have different oxygen concentrations, the final concentration of oxygen is a simple, linear function of Oxygen content of each volume Sum of the volumes (final volume) P O 2 is not a simple linear function of oxygen content or concentration.
The PO 2 of blood leaving the lungs of an upright individual will be slightly less than ideal (average) alveolar PO 2 as a result of the largest quantity of blood coming from regions with the lowest V/Q ratios, coupled with the non-linear characteristics of the oxyhemoglobin dissociation curve, skews the PO 2 of arterial blood toward the alveolar PO 2 values at the base shunts
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