ABSTRACT
Most clinicians are interested primarily in the pathogenesis and pathophysiology of those disease processes that affect the organ system with which their specialty is concerned. Common themes are emphasized: general functions expressed by most microcirculatory beds, the general structure of the microcirculation, and the broad principles that underlie microvascular failure. Some of these are illustrated by examples taken from only one microvascular bed or only one disease state, and caution must thus be exercised in extrapolation to the microcirculation in general. The microcirculation is principally concerned with the processes of transport, diffusion, and exchange of materials between blood and tissue for the purposes of metabolism, tissue defense, and repair. The microcirculation is usually defined as those vessels distal to the conduit arteries and before the veins; in addition, the prenodal lymphatics are conventionally also included. The blood microvessels comprise arterioles, the capillaries and venules, as well as specialized structures in some organ beds such as arteriovenous shunts.
