Scientists have recently made enormous strides toward elucidating the multiple functions of genes in adult animals. These advances have revealed unanticipated connections between organs and also enable us to begin asking much broader questions related to the physiology of organisms and to analyze impact of an organism's physiology on the molecular pathogenesis of degenerative diseases.Specifically addressed are the genetic basis of the known functions of many organs, the identification of novel physiological functions for various organs, and the definition of genetic cascades leading to frequent degenerative diseases such as metabolic syndrome, heart failure, and osteoporosis.