Homeostasis comprises the processes by which the organism maintains adequate intra and extracellular conditions to keep possible the normal reactions of the metabolism. Homeostatic sensors are structures that detect information from the inner and outer environment of the body. These sensors may be nervous receptor cells, cytoplasmic or membrane proteins and other specialized molecules. Controllers are structures responsible for processing and interpreting information received from the sensors. Controllers in general are specialized regions of the central nervous system but on the molecular level there are also some of them, like DNA, a molecule that can get information from proteins to inhibit or stimulate the expression of some genes. Effectors are elements commanded by the controllers that have the function of bringing about actions that in fact regulate and maintain the equilibrium of the organism, like muscles, glands, cellular organelles, etc., and in the molecular level structures that participate in the genetic translation, the produced proteins, etc.