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This review is about control of a physiological variable; what that variable's function is and how it is regulated must be discussed first to establish a rational basis for its controL The reader is referred to some excellent recent reviews on regulation of cerebral blood flow (CBF)1 (1-3). We emphasize here some functions of CBF that are not so obvious and have been largely overlooked. Cerebral blood vessels evolved as the volume of neural structures made diffusion an inefficient process to supply oxygen and nutrients to nerve cells. This being the primary drive, a close correlation can be found between intercapillary distance or capillary surface area and the level of energy exchange of the various brain regions (4-6). This structurally determined |
