Diffusion of gases.pptx

Diffusion is the process whereby gaseous atoms and molecules are transferred from regions of relatively high concentration to regions of relatively low concentration. Effusion is a similar process in which gaseous species pass from a container to a vacuum through very small orifices

1. Diffusion of Gas Exchange in Lungs Dr. K. Ambareesha PhD,. Assistant Professor Physiology, GMC, Sec,bad

2. Learning Objectives Introduction Factors on which gas exchange depends Alveolo capillary membrane Factors affectng diffusion of gses Clincal significance 4. Partial pressure gradient 5. Laws governing diffusion Henrs law Ficks law 6. Difusion coefficient 7. Capillary blood flow , its measuremt and factors affecting it

3. Diffusion of gases manly depends on: Alvelo capillary membrane Partial pressure gradient Pulmonary capillary blood flow

4. Introduction

5. I. Alveo - capillary membrane

6. Factors affecting Diffusion Difference in partial pressure Diffusing capacity Surface area Solubility of gas Thickness Molecular weight

7. DαPG DαS DαA Dα1/MW Dα1/D DαGas solubility/√MV Pressure Gradient Solubility of a gas in fluid Medium Total surface area Molecular weight of gas Thickness of membrane Diffusion coefficient FACTORS AFFECTING DIFFUSION

8. Clinical significance Alveo capillary obstruction syndrome Types: Thickening of membrane Ex: interstitial fibrosis Increased distance between alveo - capillary membrane Ex: interstitial edema in heart failure

9. Fibrosis of the lung

10. SURFACE AREA OF MEMBRANE IS ALTERD

11. SURFACE AREA OF MEMBRANE IS ALSO ALTERD

12. II. Partial pressure gradient Diffusion Gradient: Diffusion of a gas depends upon the difference of partial pressure of individual gas across the alveolo - capillary membrane of that particular gas.

13. Laws Governing Diffusion Amount of the gas dissolved in a liquid at a given temperature PP and solubility of the gas Henr’s Law: α

14. Fick’s Law Volume of the gas diffusing/min across the membrane α Membrane surface area Diffusion coefficient PP difference of a gas Thickness (T)

15. DIFFUSION OF OXYGEN

16. DIFFUSION OF OXYGEN AT CELLULAR LEVEL

17. DIFFUSION OF CO 2 AT CELLULAR LEVEL

18. DIFFUSION OF CO 2 AT ALVEOLI

19. Partial pressure of different gases

20. Diffusion coeffiient DC α its solubility √ Its MW

21. Capillary blood flow Transient time of 0.75 sec Different for different gases

22. Diffusing capacity Is a measure of rate of gas transfer into the lungs per partial pressure gradient

23. Measurement CO is used to determine Its uptake limited by diffusion Ability of CO for Hb is 210 times greater than oxygen Most common techniqu is simple breath test

24. Factors affecting DC Hb and capillary blood volume affects it It is not only depends on diffusion across the membrane and also on hematocrit A decrease in either hematocrit or capillary blood volume decreases the DC

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