The blood flow changes observed in our experiments look small in terms of forearm blood flow. The graphic is a schematic representation of the change shown in the summary data -- only in the order of a milliliter per minute per 100 ml of forearm.
Keep in mind, though, that skin makes up only, say, 5% of total limb volume. According to that proportion, the changes amount to something like 20ml/min per 100 ml of skin, a substantial change. In terms of cardiac output, this might amount to a change of 400 ml/min. This estimate can be arrived at, for a good-sized person, 2 square meters total body surface area, by estimating total skin volume of 2 liters, or by an estimate based upon the surface area of a 100ml forearm segment. Both estimates assume that the skin blood flow response is uniform over the entire body; unlikely, perhaps.
The estimated total skin blood flow change is consistent with estimates of the flow levels necessary for the transfer of body heat to the skin surface.
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rationale in experimental design(with links to methods pages)
Summary data from experiments
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