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Modeling the circulation as a supply and demand system

Existing concepts of circulatory control focus on the role of the central nervous system in adjusting cardiac output and vascular resistance to maintain a fixed arterial pressure set point. However, arterial pressure level changes in a variety of conditions and it is not clear what mechanism readjusts the postulated set point. Alternatively, we propose that the circulatory system is, at a very fundamental level, a supply and demand system in which demand determines the overall flow of product through the system. In this model the interaction between autoregulatory mechanisms of the peripheral circulation and intrinsic mechanisms of the heart (Starling's Law) determine cardiac output. Arterial pressure is not a regulated variable. This model resembles a modified free‐market economic system in which central control mechanisms modify, rather than set, supply and demand. In principle, this model should be superior to a central command model in optimizing tissue homeostasis. .A model based on this principle predicts the observed effects of decreasing vascular resistance, static exercise and dynamic exercise on cardiac output and arterial pressure. Supported by NIH grant HL 52684