The metabolic dissipation in Murray's minimum energy hypothesis includes only the blood metabolism. The metabolic dissipation of the vascular tree, however, should also include the metabolism of passive and active components of the vessel wall. In this study, we extend the metabolic dissipation to include blood metabolism, as well as passive and active components of the vessel wall. The analysis is extended to the entire vascular arterial tree rather than a single vessel as in Murray's formulation. The calculations are based on experimentally measured morphological data of coronary artery network and the longitudinal distribution of blood pressure along the tree. Whereas the model includes multiple dissipation sources, the total metabolic consumption of a complex vascular tree is found to remain approximately proportional to the cumulative arterial volume of the unit. This implies that the previously described scaling relations for the various morphological features (volume, length, diameter, and flow) remain unchanged under the generalized condition of metabolic requirements of blood and blood vessel wall. vessel wall; vascular tree; scaling laws THE CIRCULATORY SYSTEM consists of complex vascular trees that distribute and collect blood in the various organs to maintain their functions. A typical vascular tree consists of millions of vessel segments, in series and parallel, with different diameters and lengths. Although there is a great deal of heterogeneity in morphological (diameters and lengths) and hemodynamic (pressure, flow, etc.) parameters, there is a prevailing hypothesis that the design of the vascular trees obeys some simple physiological and physical principle that optimizes the operation of the system.The best-recognized minimum dissipation principle was proposed by Murray (8), in which the metabolic consumption in a single vessel segment is proportional to the blood volume. Murray's law, which states that the cube of the radius of a parent vessel equals the sum of the cube of the radii of the daughters, has been considered in various bifurcations of different organs (5,7,10,11,(13)(14)(15). On the basis of angiographic data of vascular tress, there has been important progress to establish more global relationships between morphological parameters in an entire tree and its subtrees (6). Zhou et al. (16) (ZKM model) extended Murray's cost form to stem-crown units (SCU), and they deduced a set of scaling laws that describe the optimal structure-function relationships in vascular trees. Briefly, a vessel segment was defined as a stem, and the tree distal to the stem was defined as a crown. Although the form of these scaling laws has been validated in numerous trees (3), the theory only considers the metabolic consumption of the blood. There was no consideration of the metabolic requirements of the vessel wall (passive and active).At first glance, the volume of blood to the volume of vessel wall scales as R 2 L/2RHL or R/2H, where R and H are the radius of the vessel and wall thickness, respectively. F...