els has proved to be a useful method for the study of the capillary circulation of the lung. Until recenth’, we felt that studying the capillary circulation in the component parts of the primary lobule** would reveal all the aspects of the terminal arterial circulation. It has been found, however, that the primary lobule does not disclose all the details of the terminal arterial vessels and the...

Transcapillary exchange of diffusible solutes depends on capillary blood flow, Q; capillary permeability, P; and capillary surface area, S. In a single capillary, the extent of equilibration of a given solute depends on the ratio of Q, to the product of P and S. In a microvascular bed consisting of many capillaries, equilibration depends on the fraction of them which are open to blood flow at a...

Peripheral circulation can be divided in two components: continuous one, which includes continual fluctuation of muscular vessels diameters; and discrete one, which is caused by opening and closing of pre-capillary sphincters causes the activation-deactivation of capillaries. The state of each capillary sphincter depends on concentration of tissues vasodilator metabolites in the neighborhood of...