|MadSci Network: Medicine|
The average time for an RBC to circulate is lower than you calculate, the speed of the fluid is not as high as the speed of the RBCs, RBCs are slowed in microcirculation, can be slowed by cellular attachment/detachment and by changes in fluidity associated with physiological and pathophysiological changes. On average, an RBC will live 4 months or so and transit the body 1-3 times per minute (a lot of range in that figure). As cardiac output goes up, this increases and I would estimate the figure of 35 cited by Dr. Sweet is near maximum.
Of course no one can actually directly measure the amount of time it takes one RBC to circulate through the body; these studies are done in specific vascular beds with labelled RBCs and often are comparing normal and disease states. Much work is done in the lungs for example and the numbers extrapolated to the estimated volume or vessel length of the body later. No specific research paper cites a specific number for what you seek, but many have extrapolated such numbers from the research done in this field since 1940s. Thus I am unable to give you one or a few specific citations. If you wish further detailed information, try pubmed (http://www.ncbi.nlm.nih.gov/sites/entrez) and search for RBC AND transit time. You will see some detailed papers measuring these parameters in specific vascular beds.
WK Jones, Ph.D.
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