Lectures on respiratory physiologyLectures on respiratory physiology

DiffusionDiffusion

Swim bladder of a fish

Fick’s law of diffusion through a tissue sheet

Very thin blood-gas barrier

Electron micrograph of pulmonary capillary

High power view of blood-gas barrier

Fick’s law of diffusion through a tissue sheet

Kinetic theory of gases

Fick’s law of diffusion through a tissue sheet

Diffusion and perfusion limitations

0 10 20 30 40 50 60 70 80 90 1000

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60

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PARTIAL PRESSURE, mm Hg

CO-Hb DISSOCIATION CURVES

AT

UR

AT

ION

, % CO

O2

Diffusion and perfusion limitations

Very thin blood-gas barrier

Thickened blood-gas barrier

Time courses of Po2 in the capillary

Measurement of Diffusing Capacity

Single breath method for DCO

Electron micrograph of pulmonary capillary

Reduced Hb

O2 solution

Mixing Chamber

t

Spectro Photometer

HBO2 %

100

0 0.1 0.2

time (sec)

Measurement of the rapid reaction of O2 with Hb

The two components of DL

Is the transfer of CO2 ever limited by diffusion?