The reductionist approach to study of life forms resulted in increasing use of physico-chemical concepts and techniques. Majority of these studies employed either surviving tissue model or straightaway cellfree systems.
An explosion of knowledge resulted in molecular biology. Molecular physiology became almost synonymous with biochemistry and biophysics.
However, it is now being increasingly realised that neither a purely organismic approach nor a purely reductionistic molecular approach would reveal the truth about biological processes or living phenomena.
Systems biology makes us believe that all living phenomena are emergent properties due to interaction among components of the system under study. Regulatory network of molecules, supra molecular assemblies, cells, tissues, organisms and indeed, populations and communities, each create emergent properties.
In the chapters under this unit, major human physiological processes like digestion, exchage of gases, blood circulation, locomotion and movement are described in cellular and molecular terms.
The last two chapters point to the coordination and regulation of body events at the organismic level.