Anatomy of the nutritional system

Abstract

White and brown adipocytes are contained in an anatomically dissectible structure called adipose organ. White adipocytes form white adipose tissue (WAT) brown adipocytes form brown adipose tissue (BAT). They have in common the fact that they manage lipids, but WAT uses them as an energy reserve to be given to the body between meals, while BAT burns them to produce heat. In some areas of the organ WAT and BAT are very distinct and easily recognizable by color, but in others the tissue is mixed. Numerous experimental data suggest that the concomitant presence of WAT and BAT in the adipose organ is due to the fact that they cooperate with each other thanks to their physiological and reversible transdifferentiation property. In the case of chronic cold exposure WAT converts to BAT to expand its thermogenic potential, while in the case of a chronic positive balance, BAT convert to WAT to expand the potential for energy storage. This new plastic property of physiological and reversible genetic remodeling is also present in the breast. In fact, our experimental data suggest that during pregnancy adipocytes transform into glandular epithelium that produces milk, while in the post-pregnancy period the glandular epithelium is transformed back into fat cells. The adipose organ collaborates with the digestive organs producing hormones that influence the most important of the instinctual behavioral activities: research and food intake, they also collaborate in the absorption and distribution of nutrients (both to the organism and to the offspring) and influence each other mutually for thermogenic activities that influence satiety. It can therefore be concluded that adipose organ and digestive system collaborate in a homeostatic system definable as a nutritional system.