Chapter 1 - Blood Flow in Microvascular Networks

Abstract

This chapter focuses on the flow of blood through microvascular networks, with emphasis on biophysical aspects. The need for adequate exchange of materials between blood and tissue, and particularly for oxygen delivery, is met by large numbers of closely spaced microvessels with small diameters and large cumulative surface area, interconnected in intricate network structures. microvascular network is a system of conduits that distributes blood throughout tissues as needed. The distribution of flow and pressure can be analyzed by analogy to the distribution of current and voltage in a network of electrical resistances. The flow resistance of each segment depends on the segment geometry according to the Poiseuille relationship. The topological structure of microvascular networks is heterogeneous. The biophysical processes that govern distribution of blood flow within a microvascular network of given geometry have been studied for decades and, while areas of uncertainty remain, it may be claimed that a good overall level of understanding has been achieved. Much remains to be learned, however, about the active biological processes that control network geometry, including angiogenesis, structural adaptation, and control of vascular tone. The study of blood flow in microvascular networks thus represents a key step in the process of translating advances in molecular and cellular biology into improved understanding of cardiovascular function in health and disease. A discussion of the relationship of network structure and flow to physiological aspects of the microvasculature including transport functions, inflammatory and immune functions, regulation of blood flow, and structural adaptation is presented.