Arterioles supply oxygen to capillaries by diffusion as well as by convection
| Autor: | Roland N. Pittman, M. L. Ellsworth |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Male
Convection Erythrocytes Materials science Physiology Diffusion Phase contrast microscopy chemistry.chemical_element Oxygen Microcirculation law.invention law Arteriole Cricetinae Physiology (medical) medicine.artery medicine Animals Mesocricetus Muscles Oxygen transport Arteries Anatomy Mechanics Capillaries Arterioles Cheek medicine.anatomical_structure chemistry Cardiology and Cardiovascular Medicine Blood vessel |
| Zdroj: | American Journal of Physiology-Heart and Circulatory Physiology. 258:H1240-H1243 |
| ISSN: | 1522-1539 0363-6135 |
| DOI: | 10.1152/ajpheart.1990.258.4.h1240 |
| Popis: | In the early part of this century, August Krogh proposed a model of oxygen transport in capillaries that assumes that all oxygen is delivered to the capillaries by convection from small terminal arterioles and lost from these capillaries by diffusion. This model and its consequences have been used extensively to interpret whole organ oxygen transport data in terms of diffusion between capillaries and tissues and to relate changes in microvascular hemodynamics to alterations in oxygen transport. We evaluated the appropriateness of such extrapolation by measuring oxygen saturation at discrete locations along the lengths of individual capillaries in the hamster cheek pouch retractor muscle. Our results indicate that the amount of oxygen lost from individual capillaries can be markedly affected by the presence of larger microvessels that frequently cross the capillary path. These larger vessels act either as a diffusive supply of oxygen for the red blood cells within the capillary or as an additional sink for the oxygen depending on the direction of the oxygen tension gradient. This transfer of oxygen between larger microvessels and capillaries attenuates the importance of capillary hemodynamics in oxygen exchange. Therefore, conclusions about local oxygen exchange that utilize only hemodynamic data from whole organ or microvascular experiments and the Krogh model will generally be invalid and should be viewed with caution. |
| Databáze: | OpenAIRE |
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