The autoregulation of the microcirculation.

The paper reviews August Krogh's contribution to capillary physiology stressing his formulation of useful new concepts such as "tissue cylinder model", capillary intermittency and the intimate matching of capillary perfusion and cellular metabolism. Looked upon from a control theory viewpoint. Krogh was very early in considering the microcirculation as an autoregulated system with tissue oxygen tension as the controlled parameter. Recent work on Krogh's theories is briefly summarized.