and AR are chains of signalling events, as a consequence the molecular message must be carried, directionally, from the beginning to the end of the chain (this is also the reason why the averaged number of neighbours in about 2: one is the input and the other is the output of message)...
Schematic comparison showing a sustained energy (joule) output between a poikilotherm and homeotherm as a function of core body temperature. The homeotherms have a much higher energy output range but can only function over a very narrow range of body temperatures (30 °C-40 °C in rats...