[Metabolic functions of the skin]

20 percent of the skin's energy expenditure goes on metabolic exchanges. It is in the microcirculation that the metabolic flow can be identified. The pre-terminal structures responsible for the variability of the outflow must be distinguished from the terminal structures where the hydraulic translations take place. In the network stereo-composed of terminal capillaries may be seen incidental flux (from the arteriole to the venule), interrupted transitory flux, and inverted flux. These circulatory mechanisms are admirably adapted to the variable and rhythmic needs of the metabolism. But the whole mechanism is fragile.