PIMS/Shell Lunchbox Lecture: On Oscillations in Microvascular Networks

Sustained oscillations occur in complex networks in contexts as diverse as physiology, gene regulatory networks and neural networks. Despite intensive research effort, important questions remain about the sources of oscillations in large networks. The cause of fluctuations observed in blood capillary networks has traditionally been ascribed to a large number of factors: respiration, pulsatile pressure in the arteries and arterioles, statistical variations in cell and vessel properties as well as various forms of biological control such as the contraction and dilation of the precapillary sphincters and oscillations of vascular tone (vasomotion). Complementary to studies on biological control and its influence on fluctuations in the microvasculature, convincing theoretical, numerical and experimental evidence has now been amassed in support of the contention that the flow properties of blood (hemorheological factors) alone may also induce temporal variations in the flow parameters such as pressure, flow rate and hematocrit. In this talk, we will present some further mathematical and numerical evidence to show that self-sustained oscillations of purely hemodynamical origin are possible in some arcade-type microvascular networks supplied with steady boundary conditions.