ABSTRACT
The higher organisms have a hierarchical body plan in which the whole body
system is composed of the organ system, organs, tissues, cells, and subcellular
organelles, each of which is itself composed of various compartments
(Fig. 13.1). This highly organized compartmentalization is a sophisticated
means of housing biological systems according to their speciic functions, and
homeostasis is maintained in each compartment as a nonequilibrium open
system.