1 / 11

Determinants of Diffusion

Determinants of Diffusion. Rate of Diffusion = (P 1 -P 2 ) * Area * Solubility. Distance * MW. Pressure Gradient Area Distance Solubility and MW are fixed. Changes in Alveolar Gas Composition. Figure 39-3; Guyton & Hall. Partial Pressure of Oxygen in Alveoli.

eitan
Download Presentation

Determinants of Diffusion

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Determinants of Diffusion Rate of Diffusion = (P1-P2 ) * Area * Solubility Distance * MW • Pressure Gradient • Area • Distance • Solubility and MW are fixed

  2. Changes in Alveolar Gas Composition Figure 39-3; Guyton & Hall

  3. Partial Pressure of Oxygen in Alveoli Figure 39-4: Guyton & Hall

  4. Partial Pressure of CO2 in Alveoli Figure 39-5; Guyton & Hall

  5. Alveolar and Blood Gases PO2 = 159 PCO2= 0 PO2 = 149 PCO2 = 0 PO2 = 100 PCO2= 40 PO2 = 100 PO2 = 40 PCO2= 40 PCO2= 45

  6. Diffusion Capacity 120 • Oxygen • Diff capacity 21 ml/min/mmHg * gradient of 11 mmHg • 230 ml/min diffusion of oxygen 100 80 60 in blood 40 2 Po 20 0 0 0.25 0.5 0.75 Pulmonary Capillary Length %

  7. Diffusion Capacity • Carbon Dioxide • Diff capacity 400 ml/min/mm Hg * gradient < 1 mmHg • 200 ml/min diffusion of carbon dioxide 46 45 44 43 blood Pco2 42 41 40 0 0.2 0.4 0.6 0.8 Pulmonary Capillary Length %

  8. Ventilation/Perfusion • Relationship between adequate flow and adequate ventilation • Defined as V/Q • V/Q = (4 L/min)/ (5 L/min) = 0.8

  9. pO2=? pO2=? pO2=? pCO2=? pCO2=? pCO2=? Ventilation/Perfusion V/Q = ¥ V/Q = 0 Shunt Dead space Normal Figure 39-11; Guyton & Hall

  10. Regional Gas Exchange blood flow Va/Q ventilation Top lung Bottom lung Blood flow and ventilation are not evenly matched

  11. Ventilation/Perfusion • Physiologic shunt • Va/Q < normal • low ventilation • Physiologic dead space • Va/Q > normal • wasted ventilation • Abnormalities • Upper lung Va/Q ~ 2.5 • Lower lung Va/Q ~ .5

More Related