6533b833fe1ef96bd129b6ec

RESEARCH PRODUCT

Der O2-Austausch zwischen Capillaren und Gewebe I. O2-Konzentrationsprofile in Blutcapillaren und deren Umgebung

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The differential equations valid for technical heat exchangers can also describe the O2 exchange in the blood capillaries and the exchange of molecules like THO and acetamid in the renal tubules. Differences in the boundary conditions occur, however. Hence, these differential equations were resolved for the corresponding boundary conditions. The results permit us to conclude that the concentration profiles occurring in the capillaries and renal tubules, as a result of diffusion in the capillary cross-section, can, generally speaking, be disregarded for the following reason: Although the differences in partial pressure between the capillary wall and capillary centre, at the beginning of the capillaries come to 40–60 mm Hg, they descrease rapidly. The calculations have shown, that the time constant for the saturation process of the plasma (10 msec), is small in comparison with the contact time of the blood (100 msec). In the tissue capillaries, the differences in partial pressure between the capillary wall and the centre come to about 4–6 mmHg. This difference remains constant over the total capillary length.