Our Marvelous Bodies: An Introduction to the Physiology of Human Health

For students receiving their initial exposure to the life sciences, physiology is the study of how living things work. It is the bedrock of the biomedical sciences. As the American Physiological Society expresses it, physiology is the science of life. Physiology is an analytical, experimental, investigative, and quantitative science. For the medical student completing an MD degree, or any student in the life sciences preparing to see patients, physiology is the basis of human medicine, historically and in the present. Each year a Nobel Prize is awarded in physiology or medicine. No other life science, past or present, has such a distinction.

The physiological approach to problem solving is the mechanistic approach. Physiologists use the words mechanism and mechanistic when they discuss the functions of living things. Mechanisms of function are studied by physiologists at the molecular, cellular, organ system, and whole animal levels. In the twentyfirst century, the challenge for the physiologist is to study life integratively, for example, from the molecular to the organ systems levels. The modern physiologist is also encouraged to work translationally. In other words, if their research has relevance to modern human medicine, what happens in the laboratory must be quickly transferable to the clinic. Although the idea of translational physiology is relatively recent, one of the best examples occurred in the first two decades of the twentieth century when insulin was discovered. In only a matter of weeks between its isolation and purification, insulin was used in a diabetic human subject. From that first trial in a young man in Toronto, use of insulin had an immediate and global impact on human suffering from diabetes.

Once the student understands what physiology is, it becomes easier, in many cases, to grasp the mechanistic approach by studying the relation of function to

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