Physiology is the science of understanding how living organisms function from sub-cellular level to the whole organism in physical and chemical terms. Based on knowledge of molecular interactions, the animal physiologist attempts to learn about the control and regulation of processes within cells and how a group of cells are coordinated to function as an organ. So physiology is an integrative science, rather than reductive like molecular cell biology. Many chemical and physical laws apply because living organisms are composed of elements arranged in patterns that recall the physical world . For example animal circulatory systems obey the laws of fluid dynamics and electricity.
Fluid dynamics is obvious, as blood a fluid medium flows within a restraint, the blood vessel.
But blood contains salts, so it is charged and acts as current passing through a wire. Thus hemodynamics may be studied as an electrical current. At sub-cellular levels the structure of the molecule defines the possible functions of the molecule and a specific molecular function requires a specific molecular structure . At the tissue-organismal level we see the structural arrangement of tissues will determine the possible functions and specific tissue function requires that the tissue have a certain structural arrangement . Adaptations occur slowly through evolution and are irreversible .