 A more realistic picture, some argue, features integrative unity as existing diffusely throughout the organism. As a leading proponent puts it, “What is of the essence of integrative unity is neither localized nor replaceable: namely the anti-entropic mutual interaction of all the cells and tissues of the body, mediated in mammals by circulating oxygenated blood” (Shewmon 2001, 473). On this view, the brain, like the heart and lungs, is a very important component of the interaction among body systems, but is not the supremely important integrator as suggested by the (mainstream) whole-brain approach. Nor is the functioning of other organs and bodily systems passively dependent on the brain. The brain's capacity to augment other systems presupposes their preexisting capacity to function. This is true even of a brain function as somatically integrating as the maintenance of body temperature: the “thermostat” may be in the brain, but the “furnace” is the energy metabolism diffused throughout the body. If not covered with blankets, brain-dead bodies maintained on respirators will grow colder—but not comparably to corpses (ibid, 471).