Physiologists also are fascinated with the way organisms have evolved to cope with particularly harsh environments with slight modifications to their DNA and enzyme systems. It is interesting to contemplate how primitive organisms which do not have highly evolved organ systems have managed to adapt to such environments as deserts, hot springs, fresh water, cold, heat, nutritionally poor food supply, etc. Physiologists may also specialize in determining how animals adapt to environmental stresses or how function develops along with the structure of developing, fertilized eggs. Of course other physiologists specialize in a particular system as respiration or the most popular, neurophysiology. Central Themes in Physiology.
Function is based on structure.
This is true at the molecular level as well as cellular, organ and organ system level. Enzymes can be extremely specific about the function they carry-out. Our digestive enzyme, amylase, will only separate glucose sugars that are joined in an alpha linkage. Other starches that we eat can cause problems because they are indigestible for us as some of the starches in beans. Genetics determines the proteins and enzymes that our cells will have.